two types of synthesis in literature review

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Synthesizing Sources

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When you look for areas where your sources agree or disagree and try to draw broader conclusions about your topic based on what your sources say, you are engaging in synthesis. Writing a research paper usually requires synthesizing the available sources in order to provide new insight or a different perspective into your particular topic (as opposed to simply restating what each individual source says about your research topic).

Note that synthesizing is not the same as summarizing.  

• A summary restates the information in one or more sources without providing new insight or reaching new conclusions.
• A synthesis draws on multiple sources to reach a broader conclusion.

There are two types of syntheses: explanatory syntheses and argumentative syntheses . Explanatory syntheses seek to bring sources together to explain a perspective and the reasoning behind it. Argumentative syntheses seek to bring sources together to make an argument. Both types of synthesis involve looking for relationships between sources and drawing conclusions.

In order to successfully synthesize your sources, you might begin by grouping your sources by topic and looking for connections. For example, if you were researching the pros and cons of encouraging healthy eating in children, you would want to separate your sources to find which ones agree with each other and which ones disagree.

After you have a good idea of what your sources are saying, you want to construct your body paragraphs in a way that acknowledges different sources and highlights where you can draw new conclusions.

As you continue synthesizing, here are a few points to remember:

• Don’t force a relationship between sources if there isn’t one. Not all of your sources have to complement one another.
• Do your best to highlight the relationships between sources in very clear ways.
• Don’t ignore any outliers in your research. It’s important to take note of every perspective (even those that disagree with your broader conclusions).

Example Syntheses

Below are two examples of synthesis: one where synthesis is NOT utilized well, and one where it is.

Parents are always trying to find ways to encourage healthy eating in their children. Elena Pearl Ben-Joseph, a doctor and writer for KidsHealth , encourages parents to be role models for their children by not dieting or vocalizing concerns about their body image. The first popular diet began in 1863. William Banting named it the “Banting” diet after himself, and it consisted of eating fruits, vegetables, meat, and dry wine. Despite the fact that dieting has been around for over a hundred and fifty years, parents should not diet because it hinders children’s understanding of healthy eating.

In this sample paragraph, the paragraph begins with one idea then drastically shifts to another. Rather than comparing the sources, the author simply describes their content. This leads the paragraph to veer in an different direction at the end, and it prevents the paragraph from expressing any strong arguments or conclusions.

An example of a stronger synthesis can be found below.

Parents are always trying to find ways to encourage healthy eating in their children. Different scientists and educators have different strategies for promoting a well-rounded diet while still encouraging body positivity in children. David R. Just and Joseph Price suggest in their article “Using Incentives to Encourage Healthy Eating in Children” that children are more likely to eat fruits and vegetables if they are given a reward (855-856). Similarly, Elena Pearl Ben-Joseph, a doctor and writer for Kids Health , encourages parents to be role models for their children. She states that “parents who are always dieting or complaining about their bodies may foster these same negative feelings in their kids. Try to keep a positive approach about food” (Ben-Joseph). Martha J. Nepper and Weiwen Chai support Ben-Joseph’s suggestions in their article “Parents’ Barriers and Strategies to Promote Healthy Eating among School-age Children.” Nepper and Chai note, “Parents felt that patience, consistency, educating themselves on proper nutrition, and having more healthy foods available in the home were important strategies when developing healthy eating habits for their children.” By following some of these ideas, parents can help their children develop healthy eating habits while still maintaining body positivity.

In this example, the author puts different sources in conversation with one another. Rather than simply describing the content of the sources in order, the author uses transitions (like "similarly") and makes the relationship between the sources evident.

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Get Organized

• Lit Review Prep Use this template to help you evaluate your sources, create article summaries for an annotated bibliography, and a synthesis matrix for your lit review outline.

Synthesize your Information

Synthesize: combine separate elements to form a whole.

Synthesis Matrix

A synthesis matrix helps you record the main points of each source and document how sources relate to each other.

After summarizing and evaluating your sources, arrange them in a matrix or use a citation manager to help you see how they relate to each other and apply to each of your themes or variables.  

By arranging your sources by theme or variable, you can see how your sources relate to each other, and can start thinking about how you weave them together to create a narrative.

• Step-by-Step Approach
• Example Matrix from NSCU
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• Last Updated: Sep 26, 2023 10:25 AM
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Literature Syntheis 101

How To Synthesise The Existing Research (With Examples)

By: Derek Jansen (MBA) | Expert Reviewer: Eunice Rautenbach (DTech) | August 2023

One of the most common mistakes that students make when writing a literature review is that they err on the side of describing the existing literature rather than providing a critical synthesis of it. In this post, we’ll unpack what exactly synthesis means and show you how to craft a strong literature synthesis using practical examples.

This post is based on our popular online course, Literature Review Bootcamp . In the course, we walk you through the full process of developing a literature review, step by step. If it’s your first time writing a literature review, you definitely want to use this link to get 50% off the course (limited-time offer).

Overview: Literature Synthesis

• What exactly does “synthesis” mean?
• Aspect 1: Agreement
• Aspect 2: Disagreement
• Aspect 3: Key theories
• Aspect 4: Contexts
• Aspect 5: Methodologies
• Bringing it all together

What does “synthesis” actually mean?

As a starting point, let’s quickly define what exactly we mean when we use the term “synthesis” within the context of a literature review.

Simply put, literature synthesis means going beyond just describing what everyone has said and found. Instead, synthesis is about bringing together all the information from various sources to present a cohesive assessment of the current state of knowledge in relation to your study’s research aims and questions .

Put another way, a good synthesis tells the reader exactly where the current research is “at” in terms of the topic you’re interested in – specifically, what’s known , what’s not , and where there’s a need for more research .

So, how do you go about doing this?

Well, there’s no “one right way” when it comes to literature synthesis, but we’ve found that it’s particularly useful to ask yourself five key questions when you’re working on your literature review. Having done so,  you can then address them more articulately within your actual write up. So, let’s take a look at each of these questions.

1. Points Of Agreement

The first question that you need to ask yourself is: “Overall, what things seem to be agreed upon by the vast majority of the literature?”

For example, if your research aim is to identify which factors contribute toward job satisfaction, you’ll need to identify which factors are broadly agreed upon and “settled” within the literature. Naturally, there may at times be some lone contrarian that has a radical viewpoint , but, provided that the vast majority of researchers are in agreement, you can put these random outliers to the side. That is, of course, unless your research aims to explore a contrarian viewpoint and there’s a clear justification for doing so. 

Identifying what’s broadly agreed upon is an essential starting point for synthesising the literature, because you generally don’t want (or need) to reinvent the wheel or run down a road investigating something that is already well established . So, addressing this question first lays a foundation of “settled” knowledge.

Need a helping hand?

2. Points Of Disagreement

Related to the previous point, but on the other end of the spectrum, is the equally important question: “Where do the disagreements lie?” .

In other words, which things are not well agreed upon by current researchers? It’s important to clarify here that by disagreement, we don’t mean that researchers are (necessarily) fighting over it – just that there are relatively mixed findings within the empirical research , with no firm consensus amongst researchers.

This is a really important question to address as these “disagreements” will often set the stage for the research gap(s). In other words, they provide clues regarding potential opportunities for further research, which your study can then (hopefully) contribute toward filling. If you’re not familiar with the concept of a research gap, be sure to check out our explainer video covering exactly that .

3. Key Theories

The next question you need to ask yourself is: “Which key theories seem to be coming up repeatedly?” .

Within most research spaces, you’ll find that you keep running into a handful of key theories that are referred to over and over again. Apart from identifying these theories, you’ll also need to think about how they’re connected to each other. Specifically, you need to ask yourself:

• Are they all covering the same ground or do they have different focal points  or underlying assumptions ?
• Do some of them feed into each other and if so, is there an opportunity to integrate them into a more cohesive theory?
• Do some of them pull in different directions ? If so, why might this be?
• Do all of the theories define the key concepts and variables in the same way, or is there some disconnect? If so, what’s the impact of this ?

Simply put, you’ll need to pay careful attention to the key theories in your research area, as they will need to feature within your theoretical framework , which will form a critical component within your final literature review. This will set the foundation for your entire study, so it’s essential that you be critical in this area of your literature synthesis.

If this sounds a bit fluffy, don’t worry. We deep dive into the theoretical framework (as well as the conceptual framework) and look at practical examples in Literature Review Bootcamp . If you’d like to learn more, take advantage of our limited-time offer to get 60% off the standard price.

4. Contexts

The next question that you need to address in your literature synthesis is an important one, and that is: “Which contexts have (and have not) been covered by the existing research?” .

For example, sticking with our earlier hypothetical topic (factors that impact job satisfaction), you may find that most of the research has focused on white-collar , management-level staff within a primarily Western context, but little has been done on blue-collar workers in an Eastern context. Given the significant socio-cultural differences between these two groups, this is an important observation, as it could present a contextual research gap .

In practical terms, this means that you’ll need to carefully assess the context of each piece of literature that you’re engaging with, especially the empirical research (i.e., studies that have collected and analysed real-world data). Ideally, you should keep notes regarding the context of each study in some sort of catalogue or sheet, so that you can easily make sense of this before you start the writing phase. If you’d like, our free literature catalogue worksheet is a great tool for this task.

5. Methodological Approaches

Last but certainly not least, you need to ask yourself the question: “What types of research methodologies have (and haven’t) been used?”

For example, you might find that most studies have approached the topic using qualitative methods such as interviews and thematic analysis. Alternatively, you might find that most studies have used quantitative methods such as online surveys and statistical analysis.

But why does this matter?

Well, it can run in one of two potential directions . If you find that the vast majority of studies use a specific methodological approach, this could provide you with a firm foundation on which to base your own study’s methodology . In other words, you can use the methodologies of similar studies to inform (and justify) your own study’s research design .

On the other hand, you might argue that the lack of diverse methodological approaches presents a research gap , and therefore your study could contribute toward filling that gap by taking a different approach. For example, taking a qualitative approach to a research area that is typically approached quantitatively. Of course, if you’re going to go against the methodological grain, you’ll need to provide a strong justification for why your proposed approach makes sense. Nevertheless, it is something worth at least considering.

Regardless of which route you opt for, you need to pay careful attention to the methodologies used in the relevant studies and provide at least some discussion about this in your write-up. Again, it’s useful to keep track of this on some sort of spreadsheet or catalogue as you digest each article, so consider grabbing a copy of our free literature catalogue if you don’t have anything in place.

Bringing It All Together

Alright, so we’ve looked at five important questions that you need to ask (and answer) to help you develop a strong synthesis within your literature review.  To recap, these are:

• Which things are broadly agreed upon within the current research?
• Which things are the subject of disagreement (or at least, present mixed findings)?
• Which theories seem to be central to your research topic and how do they relate or compare to each other?
• Which contexts have (and haven’t) been covered?
• Which methodological approaches are most common?

Importantly, you’re not just asking yourself these questions for the sake of asking them – they’re not just a reflection exercise. You need to weave your answers to them into your actual literature review when you write it up. How exactly you do this will vary from project to project depending on the structure you opt for, but you’ll still need to address them within your literature review, whichever route you go.

The best approach is to spend some time actually writing out your answers to these questions, as opposed to just thinking about them in your head. Putting your thoughts onto paper really helps you flesh out your thinking . As you do this, don’t just write down the answers – instead, think about what they mean in terms of the research gap you’ll present , as well as the methodological approach you’ll take . Your literature synthesis needs to lay the groundwork for these two things, so it’s essential that you link all of it together in your mind, and of course, on paper.

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

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• Research Guides

How to Write a Literature Review

• 6. Synthesize
• Literature Reviews: A Recap
• Reading Journal Articles
• Does it Describe a Literature Review?
• 1. Identify the Question
• 2. Review Discipline Styles
• Searching Article Databases
• Finding Full-Text of an Article
• Citation Chaining
• When to Stop Searching
• 4. Manage Your References
• 5. Critically Analyze and Evaluate

Synthesis Visualization

Synthesis matrix example.

• 7. Write a Literature Review

• Synthesis Worksheet

About Synthesis

Approaches to Synthesis

You can sort the literature in various ways, for example:

How to Begin?

Read your sources carefully and find the main idea(s) of each source

Look for similarities in your sources – which sources are talking about the same main ideas? (for example, sources that discuss the historical background on your topic)

Use the worksheet (above) or synthesis matrix (below) to get organized

This work can be messy. Don't worry if you have to go through a few iterations of the worksheet or matrix as you work on your lit review!

Four Examples of Student Writing

In the four examples below, only ONE shows a good example of synthesis: the fourth column, or  Student D . For a web accessible version, click the link below the image.

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• Download a copy of the "Four Examples of Student Writing" chart

Click on the example to view the pdf.

From Jennifer Lim

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How to Synthesize Written Information from Multiple Sources

Shona McCombes

Content Manager

B.A., English Literature, University of Glasgow

Shona McCombes is the content manager at Scribbr, Netherlands.

Learn about our Editorial Process

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

On This Page:

When you write a literature review or essay, you have to go beyond just summarizing the articles you’ve read – you need to synthesize the literature to show how it all fits together (and how your own research fits in).

Synthesizing simply means combining. Instead of summarizing the main points of each source in turn, you put together the ideas and findings of multiple sources in order to make an overall point.

At the most basic level, this involves looking for similarities and differences between your sources. Your synthesis should show the reader where the sources overlap and where they diverge.

Unsynthesized Example

Franz (2008) studied undergraduate online students. He looked at 17 females and 18 males and found that none of them liked APA. According to Franz, the evidence suggested that all students are reluctant to learn citations style. Perez (2010) also studies undergraduate students. She looked at 42 females and 50 males and found that males were significantly more inclined to use citation software ( p < .05). Findings suggest that females might graduate sooner. Goldstein (2012) looked at British undergraduates. Among a sample of 50, all females, all confident in their abilities to cite and were eager to write their dissertations.

Synthesized Example

Studies of undergraduate students reveal conflicting conclusions regarding relationships between advanced scholarly study and citation efficacy. Although Franz (2008) found that no participants enjoyed learning citation style, Goldstein (2012) determined in a larger study that all participants watched felt comfortable citing sources, suggesting that variables among participant and control group populations must be examined more closely. Although Perez (2010) expanded on Franz’s original study with a larger, more diverse sample…

Step 1: Organize your sources

After collecting the relevant literature, you’ve got a lot of information to work through, and no clear idea of how it all fits together.

Before you can start writing, you need to organize your notes in a way that allows you to see the relationships between sources.

One way to begin synthesizing the literature is to put your notes into a table. Depending on your topic and the type of literature you’re dealing with, there are a couple of different ways you can organize this.

Summary table

A summary table collates the key points of each source under consistent headings. This is a good approach if your sources tend to have a similar structure – for instance, if they’re all empirical papers.

Each row in the table lists one source, and each column identifies a specific part of the source. You can decide which headings to include based on what’s most relevant to the literature you’re dealing with.

For example, you might include columns for things like aims, methods, variables, population, sample size, and conclusion.

For each study, you briefly summarize each of these aspects. You can also include columns for your own evaluation and analysis.

The summary table gives you a quick overview of the key points of each source. This allows you to group sources by relevant similarities, as well as noticing important differences or contradictions in their findings.

Synthesis matrix

A synthesis matrix is useful when your sources are more varied in their purpose and structure – for example, when you’re dealing with books and essays making various different arguments about a topic.

Each column in the table lists one source. Each row is labeled with a specific concept, topic or theme that recurs across all or most of the sources.

Then, for each source, you summarize the main points or arguments related to the theme.

The purposes of the table is to identify the common points that connect the sources, as well as identifying points where they diverge or disagree.

Step 2: Outline your structure

Now you should have a clear overview of the main connections and differences between the sources you’ve read. Next, you need to decide how you’ll group them together and the order in which you’ll discuss them.

For shorter papers, your outline can just identify the focus of each paragraph; for longer papers, you might want to divide it into sections with headings.

There are a few different approaches you can take to help you structure your synthesis.

If your sources cover a broad time period, and you found patterns in how researchers approached the topic over time, you can organize your discussion chronologically .

That doesn’t mean you just summarize each paper in chronological order; instead, you should group articles into time periods and identify what they have in common, as well as signalling important turning points or developments in the literature.

If the literature covers various different topics, you can organize it thematically .

That means that each paragraph or section focuses on a specific theme and explains how that theme is approached in the literature.

Source Used with Permission: The Chicago School

If you’re drawing on literature from various different fields or they use a wide variety of research methods, you can organize your sources methodologically .

That means grouping together studies based on the type of research they did and discussing the findings that emerged from each method.

If your topic involves a debate between different schools of thought, you can organize it theoretically .

That means comparing the different theories that have been developed and grouping together papers based on the position or perspective they take on the topic, as well as evaluating which arguments are most convincing.

Step 3: Write paragraphs with topic sentences

What sets a synthesis apart from a summary is that it combines various sources. The easiest way to think about this is that each paragraph should discuss a few different sources, and you should be able to condense the overall point of the paragraph into one sentence.

This is called a topic sentence , and it usually appears at the start of the paragraph. The topic sentence signals what the whole paragraph is about; every sentence in the paragraph should be clearly related to it.

A topic sentence can be a simple summary of the paragraph’s content:

“Early research on [x] focused heavily on [y].”

For an effective synthesis, you can use topic sentences to link back to the previous paragraph, highlighting a point of debate or critique:

“Several scholars have pointed out the flaws in this approach.” “While recent research has attempted to address the problem, many of these studies have methodological flaws that limit their validity.”

By using topic sentences, you can ensure that your paragraphs are coherent and clearly show the connections between the articles you are discussing.

As you write your paragraphs, avoid quoting directly from sources: use your own words to explain the commonalities and differences that you found in the literature.

Don’t try to cover every single point from every single source – the key to synthesizing is to extract the most important and relevant information and combine it to give your reader an overall picture of the state of knowledge on your topic.

Step 4: Revise, edit and proofread

Like any other piece of academic writing, synthesizing literature doesn’t happen all in one go – it involves redrafting, revising, editing and proofreading your work.

Checklist for Synthesis

•   Do I introduce the paragraph with a clear, focused topic sentence?
•   Do I discuss more than one source in the paragraph?
•   Do I mention only the most relevant findings, rather than describing every part of the studies?
•   Do I discuss the similarities or differences between the sources, rather than summarizing each source in turn?
•   Do I put the findings or arguments of the sources in my own words?
•   Is the paragraph organized around a single idea?
•   Is the paragraph directly relevant to my research question or topic?
•   Is there a logical transition from this paragraph to the next one?

Further Information

How to Synthesise: a Step-by-Step Approach

Help…I”ve Been Asked to Synthesize!

Learn how to Synthesise (combine information from sources)

How to write a Psychology Essay

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Student Resources

How To Cite A YouTube Video In APA Style – With Examples

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APA References Page Formatting and Example

APA Title Page (Cover Page) Format, Example, & Templates

How do I Cite a Source with Multiple Authors in APA Style?

How to Write a Psychology Essay

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What Synthesis Methodology Should I Use? A Review and Analysis of Approaches to Research Synthesis

Kara schick-makaroff.

1 Faculty of Nursing, University of Alberta, Edmonton, AB, Canada

Marjorie MacDonald

2 School of Nursing, University of Victoria, Victoria, BC, Canada

Marilyn Plummer

3 College of Nursing, Camosun College, Victoria, BC, Canada

Judy Burgess

4 Student Services, University Health Services, Victoria, BC, Canada

Wendy Neander

Associated data, additional file 1.

When we began this process, we were doctoral students and a faculty member in a research methods course. As students, we were facing a review of the literature for our dissertations. We encountered several different ways of conducting a review but were unable to locate any resources that synthesized all of the various synthesis methodologies. Our purpose is to present a comprehensive overview and assessment of the main approaches to research synthesis. We use ‘research synthesis’ as a broad overarching term to describe various approaches to combining, integrating, and synthesizing research findings.

We conducted an integrative review of the literature to explore the historical, contextual, and evolving nature of research synthesis. We searched five databases, reviewed websites of key organizations, hand-searched several journals, and examined relevant texts from the reference lists of the documents we had already obtained.

We identified four broad categories of research synthesis methodology including conventional, quantitative, qualitative, and emerging syntheses. Each of the broad categories was compared to the others on the following: key characteristics, purpose, method, product, context, underlying assumptions, unit of analysis, strengths and limitations, and when to use each approach.

Conclusions

The current state of research synthesis reflects significant advancements in emerging synthesis studies that integrate diverse data types and sources. New approaches to research synthesis provide a much broader range of review alternatives available to health and social science students and researchers.

1. Introduction

Since the turn of the century, public health emergencies have been identified worldwide, particularly related to infectious diseases. For example, the Severe Acute Respiratory Syndrome (SARS) epidemic in Canada in 2002-2003, the recent Ebola epidemic in Africa, and the ongoing HIV/AIDs pandemic are global health concerns. There have also been dramatic increases in the prevalence of chronic diseases around the world [1] – [3] . These epidemiological challenges have raised concerns about the ability of health systems worldwide to address these crises. As a result, public health systems reform has been initiated in a number of countries. In Canada, as in other countries, the role of evidence to support public health reform and improve population health has been given high priority. Yet, there continues to be a significant gap between the production of evidence through research and its application in practice [4] – [5] . One strategy to address this gap has been the development of new research synthesis methodologies to deal with the time-sensitive and wide ranging evidence needs of policy makers and practitioners in all areas of health care, including public health.

As doctoral nursing students facing a review of the literature for our dissertations, and as a faculty member teaching a research methods course, we encountered several ways of conducting a research synthesis but found no comprehensive resources that discussed, compared, and contrasted various synthesis methodologies on their purposes, processes, strengths and limitations. To complicate matters, writers use terms interchangeably or use different terms to mean the same thing, and the literature is often contradictory about various approaches. Some texts [6] , [7] – [9] did provide a preliminary understanding about how research synthesis had been taken up in nursing, but these did not meet our requirements. Thus, in this article we address the need for a comprehensive overview of research synthesis methodologies to guide public health, health care, and social science researchers and practitioners.

Research synthesis is relatively new in public health but has a long history in other fields dating back to the late 1800s. Research synthesis, a research process in its own right [10] , has become more prominent in the wake of the evidence-based movement of the 1990s. Research syntheses have found their advocates and detractors in all disciplines, with challenges to the processes of systematic review and meta-analysis, in particular, being raised by critics of evidence-based healthcare [11] – [13] .

Our purpose was to conduct an integrative review of the literature to explore the historical, contextual, and evolving nature of research synthesis [14] – [15] . We synthesize and critique the main approaches to research synthesis that are relevant for public health, health care, and social scientists. Research synthesis is the overarching term we use to describe approaches to combining, aggregating, integrating, and synthesizing primary research findings. Each synthesis methodology draws on different types of findings depending on the purpose and product of the chosen synthesis (see Additional File 1 ).

3. Method of Review

Based on our current knowledge of the literature, we identified these approaches to include in our review: systematic review, meta-analysis, qualitative meta-synthesis, meta-narrative synthesis, scoping review, rapid review, realist synthesis, concept analysis, literature review, and integrative review. Our first step was to divide the synthesis types among the research team. Each member did a preliminary search to identify key texts. The team then met to develop search terms and a framework to guide the review.

Over the period of 2008 to 2012 we extensively searched the literature, updating our search at several time points, not restricting our search by date. The dates of texts reviewed range from 1967 to 2015. We used the terms above combined with the term “method* (e.g., “realist synthesis” and “method*) in the database Health Source: Academic Edition (includes Medline and CINAHL). This search yielded very few texts on some methodologies and many on others. We realized that many documents on research synthesis had not been picked up in the search. Therefore, we also searched Google Scholar, PubMed, ERIC, and Social Science Index, as well as the websites of key organizations such as the Joanna Briggs Institute, the University of York Centre for Evidence-Based Nursing, and the Cochrane Collaboration database. We hand searched several nursing, social science, public health and health policy journals. Finally, we traced relevant documents from the references in obtained texts.

We included works that met the following inclusion criteria: (1) published in English; (2) discussed the history of research synthesis; (3) explicitly described the approach and specific methods; or (4) identified issues, challenges, strengths and limitations of the particular methodology. We excluded research reports that resulted from the use of particular synthesis methodologies unless they also included criteria 2, 3, or 4 above.

Based on our search, we identified additional types of research synthesis (e.g., meta-interpretation, best evidence synthesis, critical interpretive synthesis, meta-summary, grounded formal theory). Still, we missed some important developments in meta-analysis, for example, identified by the journal's reviewers that have now been discussed briefly in the paper. The final set of 197 texts included in our review comprised theoretical, empirical, and conceptual papers, books, editorials and commentaries, and policy documents.

In our preliminary review of key texts, the team inductively developed a framework of the important elements of each method for comparison. In the next phase, each text was read carefully, and data for these elements were extracted into a table for comparison on the points of: key characteristics, purpose, methods, and product; see Additional File 1 ). Once the data were grouped and extracted, we synthesized across categories based on the following additional points of comparison: complexity of the process, degree of systematization, consideration of context, underlying assumptions, unit of analysis, and when to use each approach. In our results, we discuss our comparison of the various synthesis approaches on the elements above. Drawing only on documents for the review, ethics approval was not required.

We identified four broad categories of research synthesis methodology: Conventional, quantitative, qualitative, and emerging syntheses. From our dataset of 197 texts, we had 14 texts on conventional synthesis, 64 on quantitative synthesis, 78 on qualitative synthesis, and 41 on emerging syntheses. Table 1 provides an overview of the four types of research synthesis, definitions, types of data used, products, and examples of the methodology.

Although we group these types of synthesis into four broad categories on the basis of similarities, each type within a category has unique characteristics, which may differ from the overall group similarities. Each could be explored in greater depth to tease out their unique characteristics, but detailed comparison is beyond the scope of this article.

Additional File 1 presents one or more selected types of synthesis that represent the broad category but is not an exhaustive presentation of all types within each category. It provides more depth for specific examples from each category of synthesis on the characteristics, purpose, methods, and products than is found in Table 1 .

4.1. Key Characteristics

4.1.1. what is it.

Here we draw on two types of categorization. First, we utilize Dixon Woods et al.'s [49] classification of research syntheses as being either integrative or interpretive . (Please note that integrative syntheses are not the same as an integrative review as defined in Additional File 1 .) Second, we use Popay's [80] enhancement and epistemological models .

The defining characteristics of integrative syntheses are that they involve summarizing the data achieved by pooling data [49] . Integrative syntheses include systematic reviews, meta-analyses, as well as scoping and rapid reviews because each of these focus on summarizing data. They also define concepts from the outset (although this may not always be true in scoping or rapid reviews) and deal with a well-specified phenomenon of interest.

Interpretive syntheses are primarily concerned with the development of concepts and theories that integrate concepts [49] . The analysis in interpretive synthesis is conceptual both in process and outcome, and “the product is not aggregations of data, but theory” [49] , [p.12]. Interpretive syntheses involve induction and interpretation, and are primarily conceptual in process and outcome. Examples include integrative reviews, some systematic reviews, all of the qualitative syntheses, meta-narrative, realist and critical interpretive syntheses. Of note, both quantitative and qualitative studies can be either integrative or interpretive

The second categorization, enhancement versus epistemological , applies to those approaches that use multiple data types and sources [80] . Popay's [80] classification reflects the ways that qualitative data are valued in relation to quantitative data.

In the enhancement model , qualitative data adds something to quantitative analysis. The enhancement model is reflected in systematic reviews and meta-analyses that use some qualitative data to enhance interpretation and explanation. It may also be reflected in some rapid reviews that draw on quantitative data but use some qualitative data.

The epistemological model assumes that quantitative and qualitative data are equal and each has something unique to contribute. All of the other review approaches, except pure quantitative or qualitative syntheses, reflect the epistemological model because they value all data types equally but see them as contributing different understandings.

4.1.2. Data type

By and large, the quantitative approaches (quantitative systematic review and meta-analysis) have typically used purely quantitative data (i.e., expressed in numeric form). More recently, both Cochrane [81] and Campbell [82] collaborations are grappling with the need to, and the process of, integrating qualitative research into a systematic review. The qualitative approaches use qualitative data (i.e., expressed in words). All of the emerging synthesis types, as well as the conventional integrative review, incorporate qualitative and quantitative study designs and data.

4.1.3. Research question

Four types of research questions direct inquiry across the different types of syntheses. The first is a well-developed research question that gives direction to the synthesis (e.g., meta-analysis, systematic review, meta-study, concept analysis, rapid review, realist synthesis). The second begins as a broad general question that evolves and becomes more refined over the course of the synthesis (e.g., meta-ethnography, scoping review, meta-narrative, critical interpretive synthesis). In the third type, the synthesis begins with a phenomenon of interest and the question emerges in the analytic process (e.g., grounded formal theory). Lastly, there is no clear question, but rather a general review purpose (e.g., integrative review). Thus, the requirement for a well-defined question cuts across at least three of the synthesis types (e.g., quantitative, qualitative, and emerging).

4.1.4. Quality appraisal

This is a contested issue within and between the four synthesis categories. There are strong proponents of quality appraisal in the quantitative traditions of systematic review and meta-analysis based on the need for strong studies that will not jeopardize validity of the overall findings. Nonetheless, there is no consensus on pre-defined criteria; many scales exist that vary dramatically in composition. This has methodological implications for the credibility of findings [83] .

Specific methodologies from the conventional, qualitative, and emerging categories support quality appraisal but do so with caveats. In conventional integrative reviews appraisal is recommended, but depends on the sampling frame used in the study [18] . In meta-study, appraisal criteria are explicit but quality criteria are used in different ways depending on the specific requirements of the inquiry [54] . Among the emerging syntheses, meta-narrative review developers support appraisal of a study based on criteria from the research tradition of the primary study [67] , [84] – [85] . Realist synthesis similarly supports the use of high quality evidence, but appraisal checklists are viewed with scepticism and evidence is judged based on relevance to the research question and whether a credible inference may be drawn [69] . Like realist, critical interpretive syntheses do not judge quality using standardized appraisal instruments. They will exclude fatally flawed studies, but there is no consensus on what ‘fatally flawed’ means [49] , [71] . Appraisal is based on relevance to the inquiry, not rigor of the study.

There is no agreement on quality appraisal among qualitative meta-ethnographers with some supporting and others refuting the need for appraisal. [60] , [62] . Opponents of quality appraisal are found among authors of qualitative (grounded formal theory and concept analysis) and emerging syntheses (scoping and rapid reviews) because quality is not deemed relevant to the intention of the synthesis; the studies being reviewed are not effectiveness studies where quality is extremely important. These qualitative synthesis are often reviews of theoretical developments where the concept itself is what is important, or reviews that provide quotations from the raw data so readers can make their own judgements about the relevance and utility of the data. For example, in formal grounded theory, the purpose of theory generation and authenticity of data used to generate the theory is not as important as the conceptual category. Inaccuracies may be corrected in other ways, such as using the constant comparative method, which facilitates development of theoretical concepts that are repeatedly found in the data [86] – [87] . For pragmatic reasons, evidence is not assessed in rapid and scoping reviews, in part to produce a timely product. The issue of quality appraisal is unresolved across the terrain of research synthesis and we consider this further in our discussion.

4.2. Purpose

All research syntheses share a common purpose -- to summarize, synthesize, or integrate research findings from diverse studies. This helps readers stay abreast of the burgeoning literature in a field. Our discussion here is at the level of the four categories of synthesis. Beginning with conventional literature syntheses, the overall purpose is to attend to mature topics for the purpose of re-conceptualization or to new topics requiring preliminary conceptualization [14] . Such syntheses may be helpful to consider contradictory evidence, map shifting trends in the study of a phenomenon, and describe the emergence of research in diverse fields [14] . The purpose here is to set the stage for a study by identifying what has been done, gaps in the literature, important research questions, or to develop a conceptual framework to guide data collection and analysis.

The purpose of quantitative systematic reviews is to combine, aggregate, or integrate empirical research to be able to generalize from a group of studies and determine the limits of generalization [27] . The focus of quantitative systematic reviews has been primarily on aggregating the results of studies evaluating the effectiveness of interventions using experimental, quasi-experimental, and more recently, observational designs. Systematic reviews can be done with or without quantitative meta-analysis but a meta-analysis always takes place within the context of a systematic review. Researchers must consider the review's purpose and the nature of their data in undertaking a quantitative synthesis; this will assist in determining the approach.

The purpose of qualitative syntheses is broadly to synthesize complex health experiences, practices, or concepts arising in healthcare environments. There may be various purposes depending on the qualitative methodology. For example, in hermeneutic studies the aim may be holistic explanation or understanding of a phenomenon [42] , which is deepened by integrating the findings from multiple studies. In grounded formal theory, the aim is to produce a conceptual framework or theory expected to be applicable beyond the original study. Although not able to generalize from qualitative research in the statistical sense [88] , qualitative researchers usually do want to say something about the applicability of their synthesis to other settings or phenomena. This notion of ‘theoretical generalization’ has been referred to as ‘transferability’ [89] – [90] and is an important criterion of rigour in qualitative research. It applies equally to the products of a qualitative synthesis in which the synthesis of multiple studies on the same phenomenon strengthens the ability to draw transferable conclusions.

The overarching purpose of emerging syntheses is challenging the more traditional types of syntheses, in part by using data from both quantitative and qualitative studies with diverse designs for analysis. Beyond this, however, each emerging synthesis methodology has a unique purpose. In meta-narrative review, the purpose is to identify different research traditions in the area, synthesize a complex and diverse body of research. Critical interpretive synthesis shares this characteristic. Although a distinctive approach, critical interpretive synthesis utilizes a modification of the analytic strategies of meta-ethnography [61] (e.g., reciprocal translational analysis, refutational synthesis, and lines of argument synthesis) but goes beyond the use of these to bring a critical perspective to bear in challenging the normative or epistemological assumptions in the primary literature [72] – [73] . The unique purpose of a realist synthesis is to amalgamate complex empirical evidence and theoretical understandings within a diverse body of literature to uncover the operative mechanisms and contexts that affect the outcomes of social interventions. In a scoping review, the intention is to find key concepts, examine the range of research in an area, and identify gaps in the literature. The purpose of a rapid review is comparable to that of a scoping review, but done quickly to meet the time-sensitive information needs of policy makers.

4.3. Method

4.3.1. degree of systematization.

There are varying degrees of systematization across the categories of research synthesis. The most systematized are quantitative systematic reviews and meta-analyses. There are clear processes in each with judgments to be made at each step, although there are no agreed upon guidelines for this. The process is inherently subjective despite attempts to develop objective and systematic processes [91] – [92] . Mullen and Ramirez [27] suggest that there is often a false sense of rigour implied by the terms ‘systematic review’ and ‘meta-analysis’ because of their clearly defined procedures.

In comparison with some types of qualitative synthesis, concept analysis is quite procedural. Qualitative meta-synthesis also has defined procedures and is systematic, yet perhaps less so than concept analysis. Qualitative meta-synthesis starts in an unsystematic way but becomes more systematic as it unfolds. Procedures and frameworks exist for some of the emerging types of synthesis [e.g., [50] , [63] , [71] , [93] ] but are not linear, have considerable flexibility, and are often messy with emergent processes [85] . Conventional literature reviews tend not to be as systematic as the other three types. In fact, the lack of systematization in conventional literature synthesis was the reason for the development of more systematic quantitative [17] , [20] and qualitative [45] – [46] , [61] approaches. Some authors in the field [18] have clarified processes for integrative reviews making them more systematic and rigorous, but most conventional syntheses remain relatively unsystematic in comparison with other types.

4.3.2. Complexity of the process

Some synthesis processes are considerably more complex than others. Methodologies with clearly defined steps are arguably less complex than the more flexible and emergent ones. We know that any study encounters challenges and it is rare that a pre-determined research protocol can be followed exactly as intended. Not even the rigorous methods associated with Cochrane [81] systematic reviews and meta-analyses are always implemented exactly as intended. Even when dealing with numbers rather than words, interpretation is always part of the process. Our collective experience suggests that new methodologies (e.g., meta-narrative synthesis and realist synthesis) that integrate different data types and methods are more complex than conventional reviews or the rapid and scoping reviews.

4.4. Product

The products of research syntheses usually take three distinct formats (see Table 1 and Additional File 1 for further details). The first representation is in tables, charts, graphical displays, diagrams and maps as seen in integrative, scoping and rapid reviews, meta-analyses, and critical interpretive syntheses. The second type of synthesis product is the use of mathematical scores. Summary statements of effectiveness are mathematically displayed in meta-analyses (as an effect size), systematic reviews, and rapid reviews (statistical significance).

The third synthesis product may be a theory or theoretical framework. A mid-range theory can be produced from formal grounded theory, meta-study, meta-ethnography, and realist synthesis. Theoretical/conceptual frameworks or conceptual maps may be created in meta-narrative and critical interpretive syntheses, and integrative reviews. Concepts for use within theories are produced in concept analysis. While these three product types span the categories of research synthesis, narrative description and summary is used to present the products resulting from all methodologies.

4.5. Consideration of context

There are diverse ways that context is considered in the four broad categories of synthesis. Context may be considered to the extent that it features within primary studies for the purpose of the review. Context may also be understood as an integral aspect of both the phenomenon under study and the synthesis methodology (e.g., realist synthesis). Quantitative systematic reviews and meta-analyses have typically been conducted on studies using experimental and quasi-experimental designs and more recently observational studies, which control for contextual features to allow for understanding of the ‘true’ effect of the intervention [94] .

More recently, systematic reviews have included covariates or mediating variables (i.e., contextual factors) to help explain variability in the results across studies [27] . Context, however, is usually handled in the narrative discussion of findings rather than in the synthesis itself. This lack of attention to context has been one criticism leveled against systematic reviews and meta-analyses, which restrict the types of research designs that are considered [e.g., [95] ].

When conventional literature reviews incorporate studies that deal with context, there is a place for considering contextual influences on the intervention or phenomenon. Reviews of quantitative experimental studies tend to be devoid of contextual considerations since the original studies are similarly devoid, but context might figure prominently in a literature review that incorporates both quantitative and qualitative studies.

Qualitative syntheses have been conducted on the contextual features of a particular phenomenon [33] . Paterson et al. [54] advise researchers to attend to how context may have influenced the findings of particular primary studies. In qualitative analysis, contextual features may form categories by which the data can be compared and contrasted to facilitate interpretation. Because qualitative research is often conducted to understand a phenomenon as a whole, context may be a focus, although this varies with the qualitative methodology. At the same time, the findings in a qualitative synthesis are abstracted from the original reports and taken to a higher level of conceptualization, thus removing them from the original context.

Meta-narrative synthesis [67] , [84] , because it draws on diverse research traditions and methodologies, may incorporate context into the analysis and findings. There is not, however, an explicit step in the process that directs the analyst to consider context. Generally, the research question guiding the synthesis is an important factor in whether context will be a focus.

More recent iterations of concept analysis [47] , [96] – [97] explicitly consider context reflecting the assumption that a concept's meaning is determined by its context. Morse [47] points out, however, that Wilson's [98] approach to concept analysis, and those based on Wilson [e.g., [45] ], identify attributes that are devoid of context, while Rodgers' [96] , [99] evolutionary method considers context (e.g., antecedents, consequences, and relationships to other concepts) in concept development.

Realist synthesis [69] considers context as integral to the study. It draws on a critical realist logic of inquiry grounded in the work of Bhaskar [100] , who argues that empirical co-occurrence of events is insufficient for inferring causation. One must identify generative mechanisms whose properties are causal and, depending on the situation, may nor may not be activated [94] . Context interacts with program/intervention elements and thus cannot be differentiated from the phenomenon [69] . This approach synthesizes evidence on generative mechanisms and analyzes contextual features that activate them; the result feeds back into the context. The focus is on what works, for whom, under what conditions, why and how [68] .

4.6. Underlying Philosophical and Theoretical Assumptions

When we began our review, we ‘assumed’ that the assumptions underlying synthesis methodologies would be a distinguishing characteristic of synthesis types, and that we could compare the various types on their assumptions, explicit or implicit. We found, however, that many authors did not explicate the underlying assumptions of their methodologies, and it was difficult to infer them. Kirkevold [101] has argued that integrative reviews need to be carried out from an explicit philosophical or theoretical perspective. We argue this should be true for all types of synthesis.

Authors of some emerging synthesis approaches have been very explicit about their assumptions and philosophical underpinnings. An implicit assumption of most emerging synthesis methodologies is that quantitative systematic reviews and meta-analyses have limited utility in some fields [e.g., in public health – [13] , [102] ] and for some kinds of review questions like those about feasibility and appropriateness versus effectiveness [103] – [104] . They also assume that ontologically and epistemologically, both kinds of data can be combined. This is a significant debate in the literature because it is about the commensurability of overarching paradigms [105] but this is beyond the scope of this review.

Realist synthesis is philosophically grounded in critical realism or, as noted above, a realist logic of inquiry [93] , [99] , [106] – [107] . Key assumptions regarding the nature of interventions that inform critical realism have been described above in the section on context. See Pawson et al. [106] for more information on critical realism, the philosophical basis of realist synthesis.

Meta-narrative synthesis is explicitly rooted in a constructivist philosophy of science [108] in which knowledge is socially constructed rather than discovered, and what we take to be ‘truth’ is a matter of perspective. Reality has a pluralistic and plastic character, and there is no pre-existing ‘real world’ independent of human construction and language [109] . See Greenhalgh et al. [67] , [85] and Greenhalgh & Wong [97] for more discussion of the constructivist basis of meta-narrative synthesis.

In the case of purely quantitative or qualitative syntheses, it may be an easier matter to uncover unstated assumptions because they are likely to be shared with those of the primary studies in the genre. For example, grounded formal theory shares the philosophical and theoretical underpinnings of grounded theory, rooted in the theoretical perspective of symbolic interactionism [110] – [111] and the philosophy of pragmatism [87] , [112] – [114] .

As with meta-narrative synthesis, meta-study developers identify constructivism as their interpretive philosophical foundation [54] , [88] . Epistemologically, constructivism focuses on how people construct and re-construct knowledge about a specific phenomenon, and has three main assumptions: (1) reality is seen as multiple, at times even incompatible with the phenomenon under consideration; (2) just as primary researchers construct interpretations from participants' data, meta-study researchers also construct understandings about the primary researchers' original findings. Thus, meta-synthesis is a construction of a construction, or a meta-construction; and (3) all constructions are shaped by the historical, social and ideological context in which they originated [54] . The key message here is that reports of any synthesis would benefit from an explicit identification of the underlying philosophical perspectives to facilitate a better understanding of the results, how they were derived, and how they are being interpreted.

4.7. Unit of Analysis

The unit of analysis for each category of review is generally distinct. For the emerging synthesis approaches, the unit of analysis is specific to the intention. In meta-narrative synthesis it is the storyline in diverse research traditions; in rapid review or scoping review, it depends on the focus but could be a concept; and in realist synthesis, it is the theories rather than programs that are the units of analysis. The elements of theory that are important in the analysis are mechanisms of action, the context, and the outcome [107] .

For qualitative synthesis, the units of analysis are generally themes, concepts or theories, although in meta-study, the units of analysis can be research findings (“meta-data-analysis”), research methods (“meta-method”) or philosophical/theoretical perspectives (“meta-theory”) [54] . In quantitative synthesis, the units of analysis range from specific statistics for systematic reviews to effect size of the intervention for meta-analysis. More recently, some systematic reviews focus on theories [115] – [116] , therefore it depends on the research question. Similarly, within conventional literature synthesis the units of analysis also depend on the research purpose, focus and question as well as on the type of research methods incorporated into the review. What is important in all research syntheses, however, is that the unit of analysis needs to be made explicit. Unfortunately, this is not always the case.

4.8. Strengths and Limitations

In this section, we discuss the overarching strengths and limitations of synthesis methodologies as a whole and then highlight strengths and weaknesses across each of our four categories of synthesis.

4.8.1. Strengths of Research Syntheses in General

With the vast proliferation of research reports and the increased ease of retrieval, research synthesis has become more accessible providing a way of looking broadly at the current state of research. The availability of syntheses helps researchers, practitioners, and policy makers keep up with the burgeoning literature in their fields without which evidence-informed policy or practice would be difficult. Syntheses explain variation and difference in the data helping us identify the relevance for our own situations; they identify gaps in the literature leading to new research questions and study designs. They help us to know when to replicate a study and when to avoid excessively duplicating research. Syntheses can inform policy and practice in a way that well-designed single studies cannot; they provide building blocks for theory that helps us to understand and explain our phenomena of interest.

4.8.2. Limitations of Research Syntheses in General

The process of selecting, combining, integrating, and synthesizing across diverse study designs and data types can be complex and potentially rife with bias, even with those methodologies that have clearly defined steps. Just because a rigorous and standardized approach has been used does not mean that implicit judgements will not influence the interpretations and choices made at different stages.

In all types of synthesis, the quantity of data can be considerable, requiring difficult decisions about scope, which may affect relevance. The quantity of available data also has implications for the size of the research team. Few reviews these days can be done independently, in particular because decisions about inclusion and exclusion may require the involvement of more than one person to ensure reliability.

For all types of synthesis, it is likely that in areas with large, amorphous, and diverse bodies of literature, even the most sophisticated search strategies will not turn up all the relevant and important texts. This may be more important in some synthesis methodologies than in others, but the omission of key documents can influence the results of all syntheses. This issue can be addressed, at least in part, by including a library scientist on the research team as required by some funding agencies. Even then, it is possible to miss key texts. In this review, for example, because none of us are trained in or conduct meta-analyses, we were not even aware that we had missed some new developments in this field such as meta-regression [117] – [118] , network meta-analysis [119] – [121] , and the use of individual patient data in meta-analyses [122] – [123] .

One limitation of systematic reviews and meta-analyses is that they rapidly go out of date. We thought this might be true for all types of synthesis, although we wondered if those that produce theory might not be somewhat more enduring. We have not answered this question but it is open for debate. For all types of synthesis, the analytic skills and the time required are considerable so it is clear that training is important before embarking on a review, and some types of review may not be appropriate for students or busy practitioners.

Finally, the quality of reporting in primary studies of all genres is variable so it is sometimes difficult to identify aspects of the study essential for the synthesis, or to determine whether the study meets quality criteria. There may be flaws in the original study, or journal page limitations may necessitate omitting important details. Reporting standards have been developed for some types of reviews (e.g., systematic review, meta-analysis, meta-narrative synthesis, realist synthesis); but there are no agreed upon standards for qualitative reviews. This is an important area for development in advancing the science of research synthesis.

4.8.3. Strengths and Limitations of the Four Synthesis Types

The conventional literature review and now the increasingly common integrative review remain important and accessible approaches for students, practitioners, and experienced researchers who want to summarize literature in an area but do not have the expertise to use one of the more complex methodologies. Carefully executed, such reviews are very useful for synthesizing literature in preparation for research grants and practice projects. They can determine the state of knowledge in an area and identify important gaps in the literature to provide a clear rationale or theoretical framework for a study [14] , [18] . There is a demand, however, for more rigour, with more attention to developing comprehensive search strategies and more systematic approaches to combining, integrating, and synthesizing the findings.

Generally, conventional reviews include diverse study designs and data types that facilitate comprehensiveness, which may be a strength on the one hand, but can also present challenges on the other. The complexity inherent in combining results from studies with diverse methodologies can result in bias and inaccuracies. The absence of clear guidelines about how to synthesize across diverse study types and data [18] has been a challenge for novice reviewers.

Quantitative systematic reviews and meta-analyses have been important in launching the field of evidence-based healthcare. They provide a systematic, orderly and auditable process for conducting a review and drawing conclusions [25] . They are arguably the most powerful approaches to understanding the effectiveness of healthcare interventions, especially when intervention studies on the same topic show very different results. When areas of research are dogged by controversy [25] or when study results go against strongly held beliefs, such approaches can reduce the uncertainty and bring strong evidence to bear on the controversy.

Despite their strengths, they also have limitations. Systematic reviews and meta-analyses do not provide a way of including complex literature comprising various types of evidence including qualitative studies, theoretical work, and epidemiological studies. Only certain types of design are considered and qualitative data are used in a limited way. This exclusion limits what can be learned in a topic area.

Meta-analyses are often not possible because of wide variability in study design, population, and interventions so they may have a narrow range of utility. New developments in meta-analysis, however, can be used to address some of these limitations. Network meta-analysis is used to explore relative efficacy of multiple interventions, even those that have never been compared in more conventional pairwise meta-analyses [121] , allowing for improved clinical decision making [120] . The limitation is that network meta-analysis has only been used in medical/clinical applications [119] and not in public health. It has not yet been widely accepted and many methodological challenges remain [120] – [121] . Meta-regression is another development that combines meta-analytic and linear regression principles to address the fact that heterogeneity of results may compromise a meta-analysis [117] – [118] . The disadvantage is that many clinicians are unfamiliar with it and may incorrectly interpret results [117] .

Some have accused meta-analysis of combining apples and oranges [124] raising questions in the field about their meaningfulness [25] , [28] . More recently, the use of individual rather than aggregate data has been useful in facilitating greater comparability among studies [122] . In fact, Tomas et al. [123] argue that meta-analysis using individual data is now the gold standard although access to the raw data from other studies may be a challenge to obtain.

The usefulness of systematic reviews in synthesizing complex health and social interventions has also been challenged [102] . It is often difficult to synthesize their findings because such studies are “epistemologically diverse and methodologically complex” [ [69] , p.21]. Rigid inclusion/exclusion criteria may allow only experimental or quasi-experimental designs into consideration resulting in lost information that may well be useful to policy makers for tailoring an intervention to the context or understanding its acceptance by recipients.

Qualitative syntheses may be the type of review most fraught with controversy and challenge, while also bringing distinct strengths to the enterprise. Although these methodologies provide a comprehensive and systematic review approach, they do not generally provide definitive statements about intervention effectiveness. They do, however, address important questions about the development of theoretical concepts, patient experiences, acceptability of interventions, and an understanding about why interventions might work.

Most qualitative syntheses aim to produce a theoretically generalizable mid-range theory that explains variation across studies. This makes them more useful than single primary studies, which may not be applicable beyond the immediate setting or population. All provide a contextual richness that enhances relevance and understanding. Another benefit of some types of qualitative synthesis (e.g., grounded formal theory) is that the concept of saturation provides a sound rationale for limiting the number of texts to be included thus making reviews potentially more manageable. This contrasts with the requirements of systematic reviews and meta-analyses that require an exhaustive search.

Qualitative researchers debate about whether the findings of ontologically and epistemological diverse qualitative studies can actually be combined or synthesized [125] because methodological diversity raises many challenges for synthesizing findings. The products of different types of qualitative syntheses range from theory and conceptual frameworks, to themes and rich descriptive narratives. Can one combine the findings from a phenomenological study with the theory produced in a grounded theory study? Many argue yes, but many also argue no.

Emerging synthesis methodologies were developed to address some limitations inherent in other types of synthesis but also have their own issues. Because each type is so unique, it is difficult to identify overarching strengths of the entire category. An important strength, however, is that these newer forms of synthesis provide a systematic and rigorous approach to synthesizing a diverse literature base in a topic area that includes a range of data types such as: both quantitative and qualitative studies, theoretical work, case studies, evaluations, epidemiological studies, trials, and policy documents. More than conventional literature reviews and systematic reviews, these approaches provide explicit guidance on analytic methods for integrating different types of data. The assumption is that all forms of data have something to contribute to knowledge and theory in a topic area. All have a defined but flexible process in recognition that the methods may need to shift as knowledge develops through the process.

Many emerging synthesis types are helpful to policy makers and practitioners because they are usually involved as team members in the process to define the research questions, and interpret and disseminate the findings. In fact, engagement of stakeholders is built into the procedures of the methods. This is true for rapid reviews, meta-narrative syntheses, and realist syntheses. It is less likely to be the case for critical interpretive syntheses.

Another strength of some approaches (realist and meta-narrative syntheses) is that quality and publication standards have been developed to guide researchers, reviewers, and funders in judging the quality of the products [108] , [126] – [127] . Training materials and online communities of practice have also been developed to guide users of realist and meta-narrative review methods [107] , [128] . A unique strength of critical interpretive synthesis is that it takes a critical perspective on the process that may help reconceptualize the data in a way not considered by the primary researchers [72] .

There are also challenges of these new approaches. The methods are new and there may be few published applications by researchers other than the developers of the methods, so new users often struggle with the application. The newness of the approaches means that there may not be mentors available to guide those unfamiliar with the methods. This is changing, however, and the number of applications in the literature is growing with publications by new users helping to develop the science of synthesis [e.g., [129] ]. However, the evolving nature of the approaches and their developmental stage present challenges for novice researchers.

4.9. When to Use Each Approach

Choosing an appropriate approach to synthesis will depend on the question you are asking, the purpose of the review, and the outcome or product you want to achieve. In Additional File 1 , we discuss each of these to provide guidance to readers on making a choice about review type. If researchers want to know whether a particular type of intervention is effective in achieving its intended outcomes, then they might choose a quantitative systemic review with or without meta-analysis, possibly buttressed with qualitative studies to provide depth and explanation of the results. Alternately, if the concern is about whether an intervention is effective with different populations under diverse conditions in varying contexts, then a realist synthesis might be the most appropriate.

If researchers' concern is to develop theory, they might consider qualitative syntheses or some of the emerging syntheses that produce theory (e.g., critical interpretive synthesis, realist review, grounded formal theory, qualitative meta-synthesis). If the aim is to track the development and evolution of concepts, theories or ideas, or to determine how an issue or question is addressed across diverse research traditions, then meta-narrative synthesis would be most appropriate.

When the purpose is to review the literature in advance of undertaking a new project, particularly by graduate students, then perhaps an integrative review would be appropriate. Such efforts contribute towards the expansion of theory, identify gaps in the research, establish the rationale for studying particular phenomena, and provide a framework for interpreting results in ways that might be useful for influencing policy and practice.

For researchers keen to bring new insights, interpretations, and critical re-conceptualizations to a body of research, then qualitative or critical interpretive syntheses will provide an inductive product that may offer new understandings or challenges to the status quo. These can inform future theory development, or provide guidance for policy and practice.

5. Discussion

What is the current state of science regarding research synthesis? Public health, health care, and social science researchers or clinicians have previously used all four categories of research synthesis, and all offer a suitable array of approaches for inquiries. New developments in systematic reviews and meta-analysis are providing ways of addressing methodological challenges [117] – [123] . There has also been significant advancement in emerging synthesis methodologies and they are quickly gaining popularity. Qualitative meta-synthesis is still evolving, particularly given how new it is within the terrain of research synthesis. In the midst of this evolution, outstanding issues persist such as grappling with: the quantity of data, quality appraisal, and integration with knowledge translation. These topics have not been thoroughly addressed and need further debate.

5.1. Quantity of Data

We raise the question of whether it is possible or desirable to find all available studies for a synthesis that has this requirement (e.g., meta-analysis, systematic review, scoping, meta-narrative synthesis [25] , [27] , [63] , [67] , [84] – [85] ). Is the synthesis of all available studies a realistic goal in light of the burgeoning literature? And how can this be sustained in the future, particularly as the emerging methodologies continue to develop and as the internet facilitates endless access? There has been surprisingly little discussion on this topic and the answers will have far-reaching implications for searching, sampling, and team formation.

Researchers and graduate students can no longer rely on their own independent literature search. They will likely need to ask librarians for assistance as they navigate multiple sources of literature and learn new search strategies. Although teams now collaborate with library scientists, syntheses are limited in that researchers must make decisions on the boundaries of the review, in turn influencing the study's significance. The size of a team may also be pragmatically determined to manage the search, extraction, and synthesis of the burgeoning data. There is no single answer to our question about the possibility or necessity of finding all available articles for a review. Multiple strategies that are situation specific are likely to be needed.

5.2. Quality Appraisal

While the issue of quality appraisal has received much attention in the synthesis literature, scholars are far from resolution. There may be no agreement about appraisal criteria in a given tradition. For example, the debate rages over the appropriateness of quality appraisal in qualitative synthesis where there are over 100 different sets of criteria and many do not overlap [49] . These differences may reflect disciplinary and methodological orientations, but diverse quality appraisal criteria may privilege particular types of research [49] . The decision to appraise is often grounded in ontological and epistemological assumptions. Nonetheless, diversity within and between categories of synthesis is likely to continue unless debate on the topic of quality appraisal continues and evolves toward consensus.

5.3. Integration with Knowledge Translation

If research syntheses are to make a difference to practice and ultimately to improve health outcomes, then we need to do a better job of knowledge translation. In the Canadian Institutes of Health Research (CIHR) definition of knowledge translation (KT), research or knowledge synthesis is an integral component [130] . Yet, with few exceptions [131] – [132] , very little of the research synthesis literature even mentions the relationship of synthesis to KT nor does it discuss strategies to facilitate the integration of synthesis findings into policy and practice. The exception is in the emerging synthesis methodologies, some of which (e.g., realist and meta-narrative syntheses, scoping reviews) explicitly involve stakeholders or knowledge users. The argument is that engaging them in this way increases the likelihood that the knowledge generated will be translated into policy and practice. We suggest that a more explicit engagement with knowledge users in all types of synthesis would benefit the uptake of the research findings.

Research synthesis neither makes research more applicable to practice nor ensures implementation. Focus must now turn seriously towards translation of synthesis findings into knowledge products that are useful for health care practitioners in multiple areas of practice and develop appropriate strategies to facilitate their use. The burgeoning field of knowledge translation has, to some extent, taken up this challenge; however, the research-practice gap continues to plague us [133] – [134] . It is a particular problem for qualitative syntheses [131] . Although such syntheses have an important place in evidence-informed practice, little effort has gone into the challenge of translating the findings into useful products to guide practice [131] .

5.4. Limitations

Our study took longer than would normally be expected for an integrative review. Each of us were primarily involved in our own dissertations or teaching/research positions, and so this study was conducted ‘off the sides of our desks.’ A limitation was that we searched the literature over the course of 4 years (from 2008–2012), necessitating multiple search updates. Further, we did not do a comprehensive search of the literature after 2012, thus the more recent synthesis literature was not systematically explored. We did, however, perform limited database searches from 2012–2015 to keep abreast of the latest methodological developments. Although we missed some new approaches to meta-analysis in our search, we did not find any new features of the synthesis methodologies covered in our review that would change the analysis or findings of this article. Lastly, we struggled with the labels used for the broad categories of research synthesis methodology because of our hesitancy to reinforce the divide between quantitative and qualitative approaches. However, it was very difficult to find alternative language that represented the types of data used in these methodologies. Despite our hesitancy in creating such an obvious divide, we were left with the challenge of trying to find a way of characterizing these broad types of syntheses.

6. Conclusion

Our findings offer methodological clarity for those wishing to learn about the broad terrain of research synthesis. We believe that our review makes transparent the issues and considerations in choosing from among the four broad categories of research synthesis. In summary, research synthesis has taken its place as a form of research in its own right. The methodological terrain has deep historical roots reaching back over the past 200 years, yet research synthesis remains relatively new to public health, health care, and social sciences in general. This is rapidly changing. New developments in systematic reviews and meta-analysis, and the emergence of new synthesis methodologies provide a vast array of options to review the literature for diverse purposes. New approaches to research synthesis and new analytic methods within existing approaches provide a much broader range of review alternatives for public health, health care, and social science students and researchers.

Acknowledgments

KSM is an assistant professor in the Faculty of Nursing at the University of Alberta. Her work on this article was largely conducted as a Postdoctoral Fellow, funded by KRESCENT (Kidney Research Scientist Core Education and National Training Program, reference #KRES110011R1) and the Faculty of Nursing at the University of Alberta.

MM's work on this study over the period of 2008-2014 was supported by a Canadian Institutes of Health Research Applied Public Health Research Chair Award (grant #92365).

We thank Rachel Spanier who provided support with reference formatting.

List of Abbreviations (in Additional File 1 )

Conflict of interest: The authors declare that they have no conflicts of interest in this article.

Authors' contributions: KSM co-designed the study, collected data, analyzed the data, drafted/revised the manuscript, and managed the project.

MP contributed to searching the literature, developing the analytic framework, and extracting data for the Additional File.

JB contributed to searching the literature, developing the analytic framework, and extracting data for the Additional File.

WN contributed to searching the literature, developing the analytic framework, and extracting data for the Additional File.

All authors read and approved the final manuscript.

Additional Files: Additional File 1 – Selected Types of Research Synthesis

This Additional File is our dataset created to organize, analyze and critique the literature that we synthesized in our integrative review. Our results were created based on analysis of this Additional File.

Literature Review How To

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• Synthesizing Sources
• Video Tutorials
• Books On Literature Reviews

What is Synthesis

What is Synthesis? Synthesis writing is a form of analysis related to comparison and contrast, classification and division. On a basic level, synthesis requires the writer to pull together two or more summaries, looking for themes in each text. In synthesis, you search for the links between various materials in order to make your point. Most advanced academic writing, including literature reviews, relies heavily on synthesis. (Temple University Writing Center)  

How To Synthesize Sources in a Literature Review

Literature reviews synthesize large amounts of information and present it in a coherent, organized fashion. In a literature review you will be combining material from several texts to create a new text – your literature review.

You will use common points among the sources you have gathered to help you synthesize the material. This will help ensure that your literature review is organized by subtopic, not by source. This means various authors' names can appear and reappear throughout the literature review, and each paragraph will mention several different authors. 

When you shift from writing summaries of the content of a source to synthesizing content from sources, there is a number things you must keep in mind: 

• Look for specific connections and or links between your sources and how those relate to your thesis or question.
• When writing and organizing your literature review be aware that your readers need to understand how and why the information from the different sources overlap.
• Organize your literature review by the themes you find within your sources or themes you have identified. 
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Literature Review Basics

• What is a Literature Review?
• Synthesizing Research
• Using Research & Synthesis Tables
• Additional Resources

Synthesis: What is it?

First, let's be perfectly clear about what synthesizing your research isn't :

• - It isn't  just summarizing the material you read
• - It isn't  generating a collection of annotations or comments (like an annotated bibliography)
• - It isn't  compiling a report on every single thing ever written in relation to your topic

When you  synthesize  your research, your job is to help your reader understand the current state of the conversation on your topic, relative to your research question.  That may include doing the following:

• - Selecting and using representative work on the topic
• - Identifying and discussing trends in published data or results
• - Identifying and explaining the impact of common features (study populations, interventions, etc.) that appear frequently in the literature
• - Explaining controversies, disputes, or central issues in the literature that are relevant to your research question
• - Identifying gaps in the literature, where more research is needed
• - Establishing the discussion to which your own research contributes and demonstrating the value of your contribution

Essentially, you're telling your reader where they are (and where you are) in the scholarly conversation about your project.

Synthesis: How do I do it?

Synthesis, step by step.

This is what you need to do  before  you write your review.

• Identify and clearly describe your research question (you may find the Formulating PICOT Questions table at  the Additional Resources tab helpful).
• Collect sources relevant to your research question.
• Organize and describe the sources you've found -- your job is to identify what  types  of sources you've collected (reviews, clinical trials, etc.), identify their  purpose  (what are they measuring, testing, or trying to discover?), determine the  level of evidence  they represent (see the Levels of Evidence table at the Additional Resources tab ), and briefly explain their  major findings . Use a Research Table to document this step.
• Study the information you've put in your Research Table and examine your collected sources, looking for  similarities  and  differences . Pay particular attention to  populations ,   methods  (especially relative to levels of evidence), and  findings .
• Analyze what you learn in (4) using a tool like a Synthesis Table. Your goal is to identify relevant themes, trends, gaps, and issues in the research.  Your literature review will collect the results of this analysis and explain them in relation to your research question.

Analysis tips

• - Sometimes, what you  don't  find in the literature is as important as what you do find -- look for questions that the existing research hasn't answered yet.
• - If any of the sources you've collected refer to or respond to each other, keep an eye on how they're related -- it may provide a clue as to whether or not study results have been successfully replicated.
• - Sorting your collected sources by level of evidence can provide valuable insight into how a particular topic has been covered, and it may help you to identify gaps worth addressing in your own work.
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Chapter 7: Synthesizing Sources

Learning objectives.

At the conclusion of this chapter, you will be able to:

• synthesize key sources connecting them with the research question and topic area.

7.1 Overview of synthesizing

7.1.1 putting the pieces together.

Combining separate elements into a whole is the dictionary definition of synthesis.  It is a way to make connections among and between numerous and varied source materials.  A literature review is not an annotated bibliography, organized by title, author, or date of publication.  Rather, it is grouped by topic to create a whole view of the literature relevant to your research question.

Your synthesis must demonstrate a critical analysis of the papers you collected as well as your ability to integrate the results of your analysis into your own literature review.  Each paper collected should be critically evaluated and weighed for “adequacy, appropriateness, and thoroughness” ( Garrard, 2017 ) before inclusion in your own review.  Papers that do not meet this criteria likely should not be included in your literature review.

Begin the synthesis process by creating a grid, table, or an outline where you will summarize, using common themes you have identified and the sources you have found. The summary grid or outline will help you compare and contrast the themes so you can see the relationships among them as well as areas where you may need to do more searching. Whichever method you choose, this type of organization will help you to both understand the information you find and structure the writing of your review.  Remember, although “the means of summarizing can vary, the key at this point is to make sure you understand what you’ve found and how it relates to your topic and research question” ( Bennard et al., 2014 ).

As you read through the material you gather, look for common themes as they may provide the structure for your literature review.  And, remember, research is an iterative process: it is not unusual to go back and search information sources for more material.

At one extreme, if you are claiming, ‘There are no prior publications on this topic,’ it is more likely that you have not found them yet and may need to broaden your search.  At another extreme, writing a complete literature review can be difficult with a well-trod topic.  Do not cite it all; instead cite what is most relevant.  If that still leaves too much to include, be sure to reference influential sources…as well as high-quality work that clearly connects to the points you make. ( Klingner, Scanlon, & Pressley, 2005 ).

7.2 Creating a summary table

Literature reviews can be organized sequentially or by topic, theme, method, results, theory, or argument.  It’s important to develop categories that are meaningful and relevant to your research question.  Take detailed notes on each article and use a consistent format for capturing all the information each article provides.  These notes and the summary table can be done manually, using note cards.  However, given the amount of information you will be recording, an electronic file created in a word processing or spreadsheet is more manageable. Examples of fields you may want to capture in your notes include:

• Authors’ names
• Article title
• Publication year
• Main purpose of the article
• Methodology or research design
• Participants
• Measurement
• Conclusions

  Other fields that will be useful when you begin to synthesize the sum total of your research:

• Specific details of the article or research that are especially relevant to your study
• Key terms and definitions
• Strengths or weaknesses in research design
• Relationships to other studies
• Possible gaps in the research or literature (for example, many research articles conclude with the statement “more research is needed in this area”)
• Finally, note how closely each article relates to your topic.  You may want to rank these as high, medium, or low relevance.  For papers that you decide not to include, you may want to note your reasoning for exclusion, such as ‘small sample size’, ‘local case study,’ or ‘lacks evidence to support assertion.’

This short video demonstrates how a nursing researcher might create a summary table.

7.2.1 Creating a Summary Table

  Summary tables can be organized by author or by theme, for example:

For a summary table template, see http://blogs.monm.edu/writingatmc/files/2013/04/Synthesis-Matrix-Template.pdf

7.3 Creating a summary outline

An alternate way to organize your articles for synthesis it to create an outline. After you have collected the articles you intend to use (and have put aside the ones you won’t be using), it’s time to identify the conclusions that can be drawn from the articles as a group.

  Based on your review of the collected articles, group them by categories.  You may wish to further organize them by topic and then chronologically or alphabetically by author.  For each topic or subtopic you identified during your critical analysis of the paper, determine what those papers have in common.  Likewise, determine which ones in the group differ.  If there are contradictory findings, you may be able to identify methodological or theoretical differences that could account for the contradiction (for example, differences in population demographics).  Determine what general conclusions you can report about the topic or subtopic as the entire group of studies relate to it.  For example, you may have several studies that agree on outcome, such as ‘hands on learning is best for science in elementary school’ or that ‘continuing education is the best method for updating nursing certification.’ In that case, you may want to organize by methodology used in the studies rather than by outcome.

Organize your outline in a logical order and prepare to write the first draft of your literature review.  That order might be from broad to more specific, or it may be sequential or chronological, going from foundational literature to more current.  Remember, “an effective literature review need not denote the entire historical record, but rather establish the raison d’etre for the current study and in doing so cite that literature distinctly pertinent for theoretical, methodological, or empirical reasons.” ( Milardo, 2015, p. 22 ).

As you organize the summarized documents into a logical structure, you are also appraising and synthesizing complex information from multiple sources.  Your literature review is the result of your research that synthesizes new and old information and creates new knowledge.

7.4 Additional resources:

Literature Reviews: Using a Matrix to Organize Research / Saint Mary’s University of Minnesota

Literature Review: Synthesizing Multiple Sources / Indiana University

Writing a Literature Review and Using a Synthesis Matrix / Florida International University

 Sample Literature Reviews Grid / Complied by Lindsay Roberts

Select three or four articles on a single topic of interest to you. Then enter them into an outline or table in the categories you feel are important to a research question. Try both the grid and the outline if you can to see which suits you better. The attached grid contains the fields suggested in the video .

Literature Review Table  

Test Yourself

• Select two articles from your own summary table or outline and write a paragraph explaining how and why the sources relate to each other and your review of the literature.
• In your literature review, under what topic or subtopic will you place the paragraph you just wrote?

Image attribution

Literature Reviews for Education and Nursing Graduate Students Copyright © by Linda Frederiksen is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

• Give a new interpretation of old material or combine new with old interpretations,
• Trace the intellectual progression of the field, including major debates,
• Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
• Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

• Place each work in the context of its contribution to understanding the research problem being studied.
• Describe the relationship of each work to the others under consideration.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.
• Resolve conflicts amongst seemingly contradictory previous studies.
• Identify areas of prior scholarship to prevent duplication of effort.
• Point the way in fulfilling a need for additional research.
• Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE: Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

• An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
• Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
• An explanation of how each work is similar to and how it varies from the others,
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

• Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
• Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
• Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness -- which of the author's theses are most convincing or least convincing?
• Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

• Current Situation : Information necessary to understand the current topic or focus of the literature review.
• Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
• History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
• Standards : Description of the way in which you present your information.
• Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

• Sources in your literature review do not clearly relate to the research problem;
• You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
• Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
• Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
• Does not describe the search procedures that were used in identifying the literature to review;
• Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
• Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

• How are they organizing their ideas?
• What methods have they used to study the problem?
• What theories have been used to explain, predict, or understand their research problem?
• What sources have they cited to support their conclusions?
• How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

• Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
• Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
• Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

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Systematic Review and Evidence Synthesis

Acknowledgements.

This guide is directly informed by and selectively reuses, with permission, content from: 

• Systematic Reviews, Scoping Reviews, and other Knowledge Syntheses by Genevieve Gore and Jill Boruff, McGill University (CC-BY-NC-SA)
• A Guide to Evidence Synthesis , Cornell University Library Evidence Synthesis Service

Primary University of Minnesota Libraries authors are: Meghan Lafferty, Scott Marsalis, & Erin Reardon

Last updated: September 2022

Types of evidence synthesis

There are many types of evidence synthesis, and it is important to choose the right type of synthesis for your research questions. 

Types of evidence synthesis include (but are not limited to):

Systematic Review

Addresses a specific, answerable question of medical, scientific, policy, or management importance.

May be limited to relevant study designs depending on the type of question (e.g., intervention, prognosis, diagnosis).

Compares, critically evaluates, and synthesizes evidence.

Follows an established protocol and methodology.

May or may not include a meta-analysis of findings.

The most commonly referred-to type of evidence synthesis.

Time-intensive; can take months or longer than a year to complete.

At the top of the evidence pyramid

Meta-Analysis

Statistical technique for combining the findings from multiple quantitative studies.

Uses statistical methods to objectively evaluate, synthesize, and summarize results.

Scoping Review (or Evidence Map)

Addresses the scope of the existing literature on broad, complex, or exploratory research questions.

Many different study designs may be applicable.

Seeks to identify research gaps and opportunities for evidence synthesis.

May critically evaluate existing evidence, but does not attempt to synthesize results like a systematic review would.

Time-intensive, can take months or longer than a year to complete.

Rapid Review

Applies the methodology of a systematic review within a time-constrained setting.

Employs methodological “shortcuts” (e.g., limiting search terms) at the risk of introducing bias.

Useful for addressing issues that need a quick decision, such as developing policy recommendations or treatment recommendations for emergent conditions.

Umbrella Review

Reviews other systematic reviews on a topic.

Often attempts to answer a broader question than a systematic review typically would.

Useful when there are competing interventions to consider.

Literature (or “Narrative”) Review

A broad term that reviews with a wide scope and non-standardized methodology.

Search strategies, comprehensiveness, and time range covered may vary and do not follow an established protocol.

What Review Type?

Dr. Andrea Tricco, a leading evidence synthesis methodologist, and her team developed web-based tool to assist in selecting the right review type based on your answers to a brief list of questions. Although the tool assumes a health science topic, other disciplines may find it useful as well.

• Right Review

Main review types characterized by methods

This table summarizes the main characteristics of the 14 main review types as laid out in the seminal article on the topic. Please note that methodologies may have evolved since this article was written, so it is recommended that you review the more specific information on the following pages. Librarians can also work with you to determine the best review type for your needs.

Reproduced from: Grant, M. J. and Booth, A. (2009), A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information & Libraries Journal , 26: 91-108.  doi:10.1111/j.1471-1842.2009.00848.x  Table 1.

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• Next: Evidence Synthesis Resources Across Disciplines >>

Methodological Approaches to Literature Review

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• First Online: 09 May 2023
• Cite this living reference work entry

• Dennis Thomas 2 ,
• Elida Zairina 3 &
• Johnson George 4  

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The literature review can serve various functions in the contexts of education and research. It aids in identifying knowledge gaps, informing research methodology, and developing a theoretical framework during the planning stages of a research study or project, as well as reporting of review findings in the context of the existing literature. This chapter discusses the methodological approaches to conducting a literature review and offers an overview of different types of reviews. There are various types of reviews, including narrative reviews, scoping reviews, and systematic reviews with reporting strategies such as meta-analysis and meta-synthesis. Review authors should consider the scope of the literature review when selecting a type and method. Being focused is essential for a successful review; however, this must be balanced against the relevance of the review to a broad audience.

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Reviewing Literature for and as Research

Discussion and Conclusion

Systematic Reviews in Educational Research: Methodology, Perspectives and Application

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Thomas, D., Zairina, E., George, J. (2023). Methodological Approaches to Literature Review. In: Encyclopedia of Evidence in Pharmaceutical Public Health and Health Services Research in Pharmacy. Springer, Cham. https://doi.org/10.1007/978-3-030-50247-8_57-1

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• Synthesizing Sources | Examples & Synthesis Matrix

Synthesizing Sources | Examples & Synthesis Matrix

Published on July 4, 2022 by Eoghan Ryan . Revised on May 31, 2023.

Synthesizing sources involves combining the work of other scholars to provide new insights. It’s a way of integrating sources that helps situate your work in relation to existing research.

Synthesizing sources involves more than just summarizing . You must emphasize how each source contributes to current debates, highlighting points of (dis)agreement and putting the sources in conversation with each other.

You might synthesize sources in your literature review to give an overview of the field or throughout your research paper when you want to position your work in relation to existing research.

Table of contents

Example of synthesizing sources, how to synthesize sources, synthesis matrix, other interesting articles, frequently asked questions about synthesizing sources.

Let’s take a look at an example where sources are not properly synthesized, and then see what can be done to improve it.

This paragraph provides no context for the information and does not explain the relationships between the sources described. It also doesn’t analyze the sources or consider gaps in existing research.

Research on the barriers to second language acquisition has primarily focused on age-related difficulties. Building on Lenneberg’s (1967) theory of a critical period of language acquisition, Johnson and Newport (1988) tested Lenneberg’s idea in the context of second language acquisition. Their research seemed to confirm that young learners acquire a second language more easily than older learners. Recent research has considered other potential barriers to language acquisition. Schepens, van Hout, and van der Slik (2022) have revealed that the difficulties of learning a second language at an older age are compounded by dissimilarity between a learner’s first language and the language they aim to acquire. Further research needs to be carried out to determine whether the difficulty faced by adult monoglot speakers is also faced by adults who acquired a second language during the “critical period.”

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To synthesize sources, group them around a specific theme or point of contention.

As you read sources, ask:

• What questions or ideas recur? Do the sources focus on the same points, or do they look at the issue from different angles?
• How does each source relate to others? Does it confirm or challenge the findings of past research?
• Where do the sources agree or disagree?

Once you have a clear idea of how each source positions itself, put them in conversation with each other. Analyze and interpret their points of agreement and disagreement. This displays the relationships among sources and creates a sense of coherence.

Consider both implicit and explicit (dis)agreements. Whether one source specifically refutes another or just happens to come to different conclusions without specifically engaging with it, you can mention it in your synthesis either way.

Synthesize your sources using:

• Topic sentences to introduce the relationship between the sources
• Signal phrases to attribute ideas to their authors
• Transition words and phrases to link together different ideas

To more easily determine the similarities and dissimilarities among your sources, you can create a visual representation of their main ideas with a synthesis matrix . This is a tool that you can use when researching and writing your paper, not a part of the final text.

In a synthesis matrix, each column represents one source, and each row represents a common theme or idea among the sources. In the relevant rows, fill in a short summary of how the source treats each theme or topic.

This helps you to clearly see the commonalities or points of divergence among your sources. You can then synthesize these sources in your work by explaining their relationship.

If you want to know more about ChatGPT, AI tools , citation , and plagiarism , make sure to check out some of our other articles with explanations and examples.

• ChatGPT vs human editor
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Synthesizing sources means comparing and contrasting the work of other scholars to provide new insights.

It involves analyzing and interpreting the points of agreement and disagreement among sources.

You might synthesize sources in your literature review to give an overview of the field of research or throughout your paper when you want to contribute something new to existing research.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

Topic sentences help keep your writing focused and guide the reader through your argument.

In an essay or paper , each paragraph should focus on a single idea. By stating the main idea in the topic sentence, you clarify what the paragraph is about for both yourself and your reader.

At college level, you must properly cite your sources in all essays , research papers , and other academic texts (except exams and in-class exercises).

Add a citation whenever you quote , paraphrase , or summarize information or ideas from a source. You should also give full source details in a bibliography or reference list at the end of your text.

The exact format of your citations depends on which citation style you are instructed to use. The most common styles are APA , MLA , and Chicago .

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Teaching and Research guides

Systematic reviews.

• Starting the review
• About systematic reviews
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• Plan your search
• Sources to search
• Search example
• Screen and analyse

What is synthesis?

Quantitative synthesis (meta-analysis), qualitative synthesis.

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Synthesis is a stage in the systematic review process where extracted data (findings of individual studies) are combined and evaluated. The synthesis part of a systematic review will determine the outcomes of the review.

There are two commonly accepted methods of synthesis in systematic reviews:

• Quantitative data synthesis
• Qualitative data synthesis

The way the data is extracted from your studies and synthesised and presented depends on the type of data being handled.

If you have quantitative information, some of the more common tools used to summarise data include:

• grouping of similar data, i.e. presenting the results in tables
• charts, e.g. pie-charts
• graphical displays such as forest plots

If you have qualitative information, some of the more common tools used to summarise data include:

• textual descriptions, i.e. written words
• thematic or content analysis

Whatever tool/s you use, the general purpose of extracting and synthesising data is to show the outcomes and effects of various studies and identify issues with methodology and quality. This means that your synthesis might reveal a number of elements, including:

• overall level of evidence
• the degree of consistency in the findings
• what the positive effects of a drug or treatment are, and what these effects are based on
• how many studies found a relationship or association between two things

In a quantitative systematic review, data is presented statistically. Typically, this is referred to as a meta-analysis . 

The usual method is to combine and evaluate data from multiple studies. This is normally done in order to draw conclusions about outcomes, effects, shortcomings of studies and/or applicability of findings.

Remember, the data you synthesise should relate to your research question and protocol (plan). In the case of quantitative analysis, the data extracted and synthesised will relate to whatever method was used to generate the research question (e.g. PICO method), and whatever quality appraisals were undertaken in the analysis stage.

One way of accurately representing all of your data is in the form of a f orest plot . A forest plot is a way of combining results of multiple clinical trials in order to show point estimates arising from different studies of the same condition or treatment. 

It is comprised of a graphical representation and often also a table. The graphical display shows the mean value for each trial and often with a confidence interval (the horizontal bars). Each mean is plotted relative to the vertical line of no difference.

• Forest Plots - Understanding a Meta-Analysis in 5 Minutes or Less (5:38 min) In this video, Dr. Maureen Dobbins, Scientific Director of the National Collaborating Centre for Methods and Tools, uses an example from social health to explain how to construct a forest plot graphic.
• How to interpret a forest plot (5:32 min) In this video, Terry Shaneyfelt, Clinician-educator at UAB School of Medicine, talks about how to interpret information contained in a typical forest plot, including table data.
• An introduction to meta-analysis (13 mins) Dr Christopher J. Carpenter introduces the concept of meta-analysis, a statistical approach to finding patterns and trends among research studies on the same topic. Meta-analysis allows the researcher to weight study results based on size, moderating variables, and other factors.

Journal articles

• Neyeloff, J. L., Fuchs, S. C., & Moreira, L. B. (2012). Meta-analyses and Forest plots using a microsoft excel spreadsheet: step-by-step guide focusing on descriptive data analysis. BMC Research Notes, 5(1), 52-57. https://doi.org/10.1186/1756-0500-5-52 Provides a step-by-step guide on how to use Excel to perform a meta-analysis and generate forest plots.
• Ried, K. (2006). Interpreting and understanding meta-analysis graphs: a practical guide. Australian Family Physician, 35(8), 635- 638. This article provides a practical guide to appraisal of meta-analysis graphs, and has been developed as part of the Primary Health Care Research Evaluation Development (PHCRED) capacity building program for training general practitioners and other primary health care professionals in research methodology.

In a qualitative systematic review, data can be presented in a number of different ways. A typical procedure in the health sciences is  thematic analysis .

As explained by James Thomas and Angela Harden (2008) in an article for  BMC Medical Research Methodology : 

"Thematic synthesis has three stages:

• the coding of text 'line-by-line'
• the development of 'descriptive themes'
• and the generation of 'analytical themes'

While the development of descriptive themes remains 'close' to the primary studies, the analytical themes represent a stage of interpretation whereby the reviewers 'go beyond' the primary studies and generate new interpretive constructs, explanations or hypotheses" (p. 45).

A good example of how to conduct a thematic analysis in a systematic review is the following journal article by Jorgensen et al. (2108) on cancer patients. In it, the authors go through the process of:

(a) identifying and coding information about the selected studies' methodologies and findings on patient care

(b) organising these codes into subheadings and descriptive categories

(c) developing these categories into analytical themes

Jørgensen, C. R., Thomsen, T. G., Ross, L., Dietz, S. M., Therkildsen, S., Groenvold, M., Rasmussen, C. L., & Johnsen, A. T. (2018). What facilitates “patient empowerment” in cancer patients during follow-up: A qualitative systematic review of the literature. Qualitative Health Research, 28(2), 292-304. https://doi.org/10.1177/1049732317721477

Thomas, J., & Harden, A. (2008). Methods for the thematic synthesis of qualitative research in systematic reviews. BMC Medical Research Methodology, 8(1), 45-54. https://doi.org/10.1186/1471-2288-8-45

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Systematic reviews & evidence synthesis methods.

• Schedule a Consultation / Meet our Team
• What is Evidence Synthesis?
• Types of Evidence Synthesis
• Evidence Synthesis Across Disciplines
• Finding and Appraising Existing Systematic Reviews
• 0. Preliminary Searching
• 1. Develop a Protocol
• 2. Draft your Research Question
• 3. Select Databases
• 4. Select Grey Literature Sources
• 5. Write a Search Strategy
• 6. Register a Protocol
• 7. Translate Search Strategies
• 8. Citation Management
• 9. Article Screening
• 10. Risk of Bias Assessment
• 11. Data Extraction
• 12. Synthesize, Map, or Describe the Results
• Open Access Evidence Synthesis Resources

What are evidence syntheses?

According to the Royal Society, 'evidence synthesis' refers to the process of bringing together information from a range of sources and disciplines to inform debates and decisions on specific issues. They generally include a methodical and comprehensive literature synthesis focused on a well-formulated research question. Their aim is to identify and synthesize all of the scholarly research on a particular topic, including both published and unpublished studies. Evidence syntheses are conducted in an unbiased, reproducible way to provide evidence for practice and policy-making, as well as to identify gaps in the research. Evidence syntheses may also include a meta-analysis, a more quantitative process of synthesizing and visualizing data retrieved from various studies.

Evidence syntheses are much more time-intensive than traditional literature reviews and require a multi-person research team. See this PredicTER tool to get a sense of a systematic review timeline (one type of evidence synthesis). Before embarking on an evidence synthesis, it's important to clearly identify your reasons for conducting one. For a list of types of evidence synthesis projects, see the Types of Evidence Synthesis tab.

How does a traditional literature review differ from evidence synthesis?

One commonly used form of evidence synthesis is a systematic review. This table compares a traditional literature review with a systematic review.

Video: Reproducibility and transparent methods (Video 3:25)

Reporting standards

There are some reporting standards for evidence syntheses. These can serve as guidelines for protocol and manuscript preparation and journals may require that these standards are followed for the review type that is being employed (e.g. systematic review, scoping review, etc).​

• PRISMA checklist Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses.
• PRISMA-P Standards An updated version of the original PRISMA standards for protocol development.
• PRISMA - ScR Reporting guidelines for scoping reviews and evidence maps
• PRISMA-IPD Standards Extension of the original PRISMA standards for systematic reviews and meta-analyses of individual participant data.
• EQUATOR Network The EQUATOR (Enhancing the QUAlity and Transparency Of health Research) Network is an international initiative that seeks to improve the reliability and value of published health research literature by promoting transparent and accurate reporting and wider use of robust reporting guidelines. They provide a list of various standards for reporting in systematic reviews.

Video: Guidelines and reporting standards

PRISMA flow diagram

The PRISMA flow diagram depicts the flow of information through the different phases of an evidence synthesis. It maps the search (number of records identified), screening (number of records included and excluded), and selection (reasons for exclusion). Many evidence syntheses include a PRISMA flow diagram in the published manuscript.

See below for resources to help you generate your own PRISMA flow diagram.

• PRISMA Flow Diagram Tool
• PRISMA Flow Diagram Word Template
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Types of Literature Review — A Guide for Researchers

Table of Contents

Researchers often face challenges when choosing the appropriate type of literature review for their study. Regardless of the type of research design and the topic of a research problem , they encounter numerous queries, including:

What is the right type of literature review my study demands?

• How do we gather the data?
• How to conduct one?
• How reliable are the review findings?
• How do we employ them in our research? And the list goes on.

If you’re also dealing with such a hefty questionnaire, this article is of help. Read through this piece of guide to get an exhaustive understanding of the different types of literature reviews and their step-by-step methodologies along with a dash of pros and cons discussed.

Heading from scratch!

What is a Literature Review?

A literature review provides a comprehensive overview of existing knowledge on a particular topic, which is quintessential to any research project. Researchers employ various literature reviews based on their research goals and methodologies. The review process involves assembling, critically evaluating, and synthesizing existing scientific publications relevant to the research question at hand. It serves multiple purposes, including identifying gaps in existing literature, providing theoretical background, and supporting the rationale for a research study.

What is the importance of a Literature review in research?

Literature review in research serves several key purposes, including:

• Background of the study: Provides proper context for the research. It helps researchers understand the historical development, theoretical perspectives, and key debates related to their research topic.
• Identification of research gaps: By reviewing existing literature, researchers can identify gaps or inconsistencies in knowledge, paving the way for new research questions and hypotheses relevant to their study.
• Theoretical framework development: Facilitates the development of theoretical frameworks by cultivating diverse perspectives and empirical findings. It helps researchers refine their conceptualizations and theoretical models.
• Methodological guidance: Offers methodological guidance by highlighting the documented research methods and techniques used in previous studies. It assists researchers in selecting appropriate research designs, data collection methods, and analytical tools.
• Quality assurance and upholding academic integrity: Conducting a thorough literature review demonstrates the rigor and scholarly integrity of the research. It ensures that researchers are aware of relevant studies and can accurately attribute ideas and findings to their original sources.

Types of Literature Review

Literature review plays a crucial role in guiding the research process , from providing the background of the study to research dissemination and contributing to the synthesis of the latest theoretical literature review findings in academia.

However, not all types of literature reviews are the same; they vary in terms of methodology, approach, and purpose. Let's have a look at the various types of literature reviews to gain a deeper understanding of their applications.

1. Narrative Literature Review

A narrative literature review, also known as a traditional literature review, involves analyzing and summarizing existing literature without adhering to a structured methodology. It typically provides a descriptive overview of key concepts, theories, and relevant findings of the research topic.

Unlike other types of literature reviews, narrative reviews reinforce a more traditional approach, emphasizing the interpretation and discussion of the research findings rather than strict adherence to methodological review criteria. It helps researchers explore diverse perspectives and insights based on the research topic and acts as preliminary work for further investigation.

Steps to Conduct a Narrative Literature Review

Source:- https://www.researchgate.net/figure/Steps-of-writing-a-narrative-review_fig1_354466408

Define the research question or topic:

The first step in conducting a narrative literature review is to clearly define the research question or topic of interest. Defining the scope and purpose of the review includes — What specific aspect of the topic do you want to explore? What are the main objectives of the research? Refine your research question based on the specific area you want to explore.

Conduct a thorough literature search

Once the research question is defined, you can conduct a comprehensive literature search. Explore and use relevant databases and search engines like SciSpace Discover to identify credible and pertinent, scholarly articles and publications.

Select relevant studies

Before choosing the right set of studies, it’s vital to determine inclusion (studies that should possess the required factors) and exclusion criteria for the literature and then carefully select papers. For example — Which studies or sources will be included based on relevance, quality, and publication date?

*Important (applies to all the reviews): Inclusion criteria are the factors a study must include (For example: Include only peer-reviewed articles published between 2022-2023, etc.). Exclusion criteria are the factors that wouldn’t be required for your search strategy (Example: exclude irrelevant papers, preprints, written in non-English, etc.)

Critically analyze the literature

Once the relevant studies are shortlisted, evaluate the methodology, findings, and limitations of each source and jot down key themes, patterns, and contradictions. You can use efficient AI tools to conduct a thorough literature review and analyze all the required information.

Synthesize and integrate the findings

Now, you can weave together the reviewed studies, underscoring significant findings such that new frameworks, contrasting viewpoints, and identifying knowledge gaps.

Discussion and conclusion

This is an important step before crafting a narrative review — summarize the main findings of the review and discuss their implications in the relevant field. For example — What are the practical implications for practitioners? What are the directions for future research for them?

Write a cohesive narrative review

Organize the review into coherent sections and structure your review logically, guiding the reader through the research landscape and offering valuable insights. Use clear and concise language to convey key points effectively.

Structure of Narrative Literature Review

A well-structured, narrative analysis or literature review typically includes the following components:

• Introduction: Provides an overview of the topic, objectives of the study, and rationale for the review.
• Background: Highlights relevant background information and establish the context for the review.
• Main Body: Indexes the literature into thematic sections or categories, discussing key findings, methodologies, and theoretical frameworks.
• Discussion: Analyze and synthesize the findings of the reviewed studies, stressing similarities, differences, and any gaps in the literature.
• Conclusion: Summarizes the main findings of the review, identifies implications for future research, and offers concluding remarks.

Pros and Cons of Narrative Literature Review

• Flexibility in methodology and doesn’t necessarily rely on structured methodologies
• Follows traditional approach and provides valuable and contextualized insights
• Suitable for exploring complex or interdisciplinary topics. For example — Climate change and human health, Cybersecurity and privacy in the digital age, and more
• Subjectivity in data selection and interpretation
• Potential for bias in the review process
• Lack of rigor compared to systematic reviews

Example of Well-Executed Narrative Literature Reviews

Paper title:  Examining Moral Injury in Clinical Practice: A Narrative Literature Review

Source: SciSpace

While narrative reviews offer flexibility, academic integrity remains paramount. So, ensure proper citation of all sources and maintain a transparent and factual approach throughout your critical narrative review, itself.

2. Systematic Review

A systematic literature review is one of the comprehensive types of literature review that follows a structured approach to assembling, analyzing, and synthesizing existing research relevant to a particular topic or question. It involves clearly defined criteria for exploring and choosing studies, as well as rigorous methods for evaluating the quality of relevant studies.

It plays a prominent role in evidence-based practice and decision-making across various domains, including healthcare, social sciences, education, health sciences, and more. By systematically investigating available literature, researchers can identify gaps in knowledge, evaluate the strength of evidence, and report future research directions.

Steps to Conduct Systematic Reviews

Source:- https://www.researchgate.net/figure/Steps-of-Systematic-Literature-Review_fig1_321422320

Here are the key steps involved in conducting a systematic literature review

Formulate a clear and focused research question

Clearly define the research question or objective of the review. It helps to centralize the literature search strategy and determine inclusion criteria for relevant studies.

Develop a thorough literature search strategy

Design a comprehensive search strategy to identify relevant studies. It involves scrutinizing scientific databases and all relevant articles in journals. Plus, seek suggestions from domain experts and review reference lists of relevant review articles.

Screening and selecting studies

Employ predefined inclusion and exclusion criteria to systematically screen the identified studies. This screening process also typically involves multiple reviewers independently assessing the eligibility of each study.

Data extraction

Extract key information from selected studies using standardized forms or protocols. It includes study characteristics, methods, results, and conclusions.

Critical appraisal

Evaluate the methodological quality and potential biases of included studies. Various tools (BMC medical research methodology) and criteria can be implemented for critical evaluation depending on the study design and research quetions .

Data synthesis

Analyze and synthesize review findings from individual studies to draw encompassing conclusions or identify overarching patterns and explore heterogeneity among studies.

Interpretation and conclusion

Interpret the findings about the research question, considering the strengths and limitations of the research evidence. Draw conclusions and implications for further research.

The final step — Report writing

Craft a detailed report of the systematic literature review adhering to the established guidelines of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). This ensures transparency and reproducibility of the review process.

By following these steps, a systematic literature review aims to provide a comprehensive and unbiased summary of existing evidence, help make informed decisions, and advance knowledge in the respective domain or field.

Structure of a systematic literature review

A well-structured systematic literature review typically consists of the following sections:

• Introduction: Provides background information on the research topic, outlines the review objectives, and enunciates the scope of the study.
• Methodology: Describes the literature search strategy, selection criteria, data extraction process, and other methods used for data synthesis, extraction, or other data analysis..
• Results: Presents the review findings, including a summary of the incorporated studies and their key findings.
• Discussion: Interprets the findings in light of the review objectives, discusses their implications, and identifies limitations or promising areas for future research.
• Conclusion: Summarizes the main review findings and provides suggestions based on the evidence presented in depth meta analysis.

*Important (applies to all the reviews): Remember, the specific structure of your literature review may vary depending on your topic, research question, and intended audience. However, adhering to a clear and logical hierarchy ensures your review effectively analyses and synthesizes knowledge and contributes valuable insights for readers.

Pros and Cons of Systematic Literature Review

• Adopts rigorous and transparent methodology
• Minimizes bias and enhances the reliability of the study
• Provides evidence-based insights
• Time and resource-intensive
• High dependency on the quality of available literature (literature research strategy should be accurate)
• Potential for publication bias

Example of Well-Executed Systematic Literature Review

Paper title: Systematic Reviews: Understanding the Best Evidence For Clinical Decision-making in Health Care: Pros and Cons.

Read this detailed article on how to use AI tools to conduct a systematic review for your research!

3. Scoping Literature Review

A scoping literature review is a methodological review type of literature review that adopts an iterative approach to systematically map the existing literature on a particular topic or research area. It involves identifying, selecting, and synthesizing relevant papers to provide an overview of the size and scope of available evidence. Scoping reviews are broader in scope and include a diverse range of study designs and methodologies especially focused on health services research.

The main purpose of a scoping literature review is to examine the extent, range, and nature of existing studies on a topic, thereby identifying gaps in research, inconsistencies, and areas for further investigation. Additionally, scoping reviews can help researchers identify suitable methodologies and formulate clinical recommendations. They also act as the frameworks for future systematic reviews or primary research studies.

Scoping reviews are primarily focused on —

• Emerging or evolving topics — where the research landscape is still growing or budding. Example — Whole Systems Approaches to Diet and Healthy Weight: A Scoping Review of Reviews .
• Broad and complex topics : With a vast amount of existing literature.
• Scenarios where a systematic review is not feasible: Due to limited resources or time constraints.

Steps to Conduct a Scoping Literature Review

While Scoping reviews are not as rigorous as systematic reviews, however, they still follow a structured approach. Here are the steps:

Identify the research question: Define the broad topic you want to explore.

Identify Relevant Studies: Conduct a comprehensive search of relevant literature using appropriate databases, keywords, and search strategies.

Select studies to be included in the review: Based on the inclusion and exclusion criteria, determine the appropriate studies to be included in the review.

Data extraction and charting : Extract relevant information from selected studies, such as year, author, main results, study characteristics, key findings, and methodological approaches.  However, it varies depending on the research question.

Collate, summarize, and report the results: Analyze and summarize the extracted data to identify key themes and trends. Then, present the findings of the scoping review in a clear and structured manner, following established guidelines and frameworks .

Structure of a Scoping Literature Review

A scoping literature review typically follows a structured format similar to a systematic review. It includes the following sections:

• Introduction: Introduce the research topic and objectives of the review, providing the historical context, and rationale for the study.
• Methods : Describe the methods used to conduct the review, including search strategies, study selection criteria, and data extraction procedures.
• Results: Present the findings of the review, including key themes, concepts, and patterns identified in the literature review.
• Discussion: Examine the implications of the findings, including strengths, limitations, and areas for further examination.
• Conclusion: Recapitulate the main findings of the review and their implications for future research, policy, or practice.

Pros and Cons of Scoping Literature Review

• Provides a comprehensive overview of existing literature
• Helps to identify gaps and areas for further research
• Suitable for exploring broad or complex research questions
• Doesn’t provide the depth of analysis offered by systematic reviews
• Subject to researcher bias in study selection and data extraction
• Requires careful consideration of literature search strategies and inclusion criteria to ensure comprehensiveness and validity.

In short, a scoping review helps map the literature on developing or emerging topics and identifying gaps. It might be considered as a step before conducting another type of review, such as a systematic review. Basically, acts as a precursor for other literature reviews.

Example of a Well-Executed Scoping Literature Review

Paper title: Health Chatbots in Africa Literature: A Scoping Review

Check out the key differences between Systematic and Scoping reviews — Evaluating literature review: systematic vs. scoping reviews

4. Integrative Literature Review

Integrative Literature Review (ILR) is a type of literature review that proposes a distinctive way to analyze and synthesize existing literature on a specific topic, providing a thorough understanding of research and identifying potential gaps for future research.

Unlike a systematic review, which emphasizes quantitative studies and follows strict inclusion criteria, an ILR embraces a more pliable approach. It works beyond simply summarizing findings — it critically analyzes, integrates, and interprets research from various methodologies (qualitative, quantitative, mixed methods) to provide a deeper understanding of the research landscape. ILRs provide a holistic and systematic overview of existing research, integrating findings from various methodologies. ILRs are ideal for exploring intricate research issues, examining manifold perspectives, and developing new research questions.

Steps to Conduct an Integrative Literature Review

• Identify the research question: Clearly define the research question or topic of interest as formulating a clear and focused research question is critical to leading the entire review process.
• Literature search strategy: Employ systematic search techniques to locate relevant literature across various databases and sources.
• Evaluate the quality of the included studies : Critically assess the methodology, rigor, and validity of each study by applying inclusion and exclusion criteria to filter and select studies aligned with the research objectives.
• Data Extraction: Extract relevant data from selected studies using a structured approach.
• Synthesize the findings : Thoroughly analyze the selected literature, identify key themes, and synthesize findings to derive noteworthy insights.
• Critical appraisal: Critically evaluate the quality and validity of qualitative research and included studies by using BMC medical research methodology.
• Interpret and present your findings: Discuss the purpose and implications of your analysis, spotlighting key insights and limitations. Organize and present the findings coherently and systematically.

Structure of an Integrative Literature Review

• Introduction : Provide an overview of the research topic and the purpose of the integrative review.
• Methods: Describe the opted literature search strategy, selection criteria, and data extraction process.
• Results: Present the synthesized findings, including key themes, patterns, and contradictions.
• Discussion: Interpret the findings about the research question, emphasizing implications for theory, practice, and prospective research.
• Conclusion: Summarize the main findings, limitations, and contributions of the integrative review.

Pros and Cons of Integrative Literature Review

• Informs evidence-based practice and policy to the relevant stakeholders of the research.
• Contributes to theory development and methodological advancement, especially in the healthcare arena.
• Integrates diverse perspectives and findings
• Time-consuming process due to the extensive literature search and synthesis
• Requires advanced analytical and critical thinking skills
• Potential for bias in study selection and interpretation
• The quality of included studies may vary, affecting the validity of the review

Example of Integrative Literature Reviews

Paper Title: An Integrative Literature Review: The Dual Impact of Technological Tools on Health and Technostress Among Older Workers

5. Rapid Literature Review

A Rapid Literature Review (RLR) is the fastest type of literature review which makes use of a streamlined approach for synthesizing literature summaries, offering a quicker and more focused alternative to traditional systematic reviews. Despite employing identical research methods, it often simplifies or omits specific steps to expedite the process. It allows researchers to gain valuable insights into current research trends and identify key findings within a shorter timeframe, often ranging from a few days to a few weeks — unlike traditional literature reviews, which may take months or even years to complete.

When to Consider a Rapid Literature Review?

• When time impediments demand a swift summary of existing research
• For emerging topics where the latest literature requires quick evaluation
• To report pilot studies or preliminary research before embarking on a comprehensive systematic review

Steps to Conduct a Rapid Literature Review

• Define the research question or topic of interest. A well-defined question guides the search process and helps researchers focus on relevant studies.
• Determine key databases and sources of relevant literature to ensure comprehensive coverage.
• Develop literature search strategies using appropriate keywords and filters to fetch a pool of potential scientific articles.
• Screen search results based on predefined inclusion and exclusion criteria.
• Extract and summarize relevant information from the above-preferred studies.
• Synthesize findings to identify key themes, patterns, or gaps in the literature.
• Prepare a concise report or a summary of the RLR findings.

Structure of a Rapid Literature Review

An effective structure of an RLR typically includes the following sections:

• Introduction: Briefly introduce the research topic and objectives of the RLR.
• Methodology: Describe the search strategy, inclusion and exclusion criteria, and data extraction process.
• Results: Present a summary of the findings, including key themes or patterns identified.
• Discussion: Interpret the findings, discuss implications, and highlight any limitations or areas for further research
• Conclusion: Summarize the key findings and their implications for practice or future research

Pros and Cons of Rapid Literature Review

• RLRs can be completed quickly, authorizing timely decision-making
• RLRs are a cost-effective approach since they require fewer resources compared to traditional literature reviews
• Offers great accessibility as RLRs provide prompt access to synthesized evidence for stakeholders
• RLRs are flexible as they can be easily adapted for various research contexts and objectives
• RLR reports are limited and restricted, not as in-depth as systematic reviews, and do not provide comprehensive coverage of the literature compared to traditional reviews.
• Susceptible to bias because of the expedited nature of RLRs. It would increase the chance of overlooking relevant studies or biases in the selection process.
• Due to time constraints, RLR findings might not be robust enough as compared to systematic reviews.

Example of a Well-Executed Rapid Literature Review

Paper Title: What Is the Impact of ChatGPT on Education? A Rapid Review of the Literature

A Summary of Literature Review Types

Tools and Resources for Conducting Different Types of Literature Reviews

Online scientific databases.

Platforms such as SciSpace , PubMed , Scopus , Elsevier , and Web of Science provide access to a vast array of scholarly literature, facilitating the search and data retrieval process.

Reference management software

Tools like SciSpace Citation Generator , EndNote, Zotero , and Mendeley assist researchers in organizing, annotating, and citing relevant literature, streamlining the review process altogether.

Automate Literature Review with AI tools

Automate the literature review process by using tools like SciSpace literature review which helps you compare and contrast multiple papers all on one screen in an easy-to-read matrix format. You can effortlessly analyze and interpret the review findings tailored to your study. It also supports the review in 75+ languages, making it more manageable even for non-English speakers.

Goes without saying — literature review plays a pivotal role in academic research to identify the current trends and provide insights to pave the way for future research endeavors. Different types of literature review has their own strengths and limitations, making them suitable for different research designs and contexts. Whether conducting a narrative review, systematic review, scoping review, integrative review, or rapid literature review, researchers must cautiously consider the objectives, resources, and the nature of the research topic.

If you’re currently working on a literature review and still adopting a manual and traditional approach, switch to the automated AI literature review workspace and transform your traditional literature review into a rapid one by extracting all the latest and relevant data for your research!

There you go!

Frequently Asked Questions

Narrative reviews give a general overview of a topic based on the author's knowledge. They may lack clear criteria and can be biased. On the other hand, systematic reviews aim to answer specific research questions by following strict methods. They're thorough but time-consuming.

A systematic review collects and analyzes existing research to provide an overview of a topic, while a meta-analysis statistically combines data from multiple studies to draw conclusions about the overall effect of an intervention or relationship between variables.

A systematic review thoroughly analyzes existing research on a specific topic using strict methods. In contrast, a scoping review offers a broader overview of the literature without evaluating individual studies in depth.

A systematic review thoroughly examines existing research using a rigorous process, while a rapid review provides a quicker summary of evidence, often by simplifying some of the systematic review steps to meet shorter timelines.

A systematic review carefully examines many studies on a single topic using specific guidelines. Conversely, an integrative review blends various types of research to provide a more comprehensive understanding of the topic.

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Types of Literature Review

There are many types of literature review. The choice of a specific type depends on your research approach and design. The following types of literature review are the most popular in business studies:

Narrative literature review , also referred to as traditional literature review, critiques literature and summarizes the body of a literature. Narrative review also draws conclusions about the topic and identifies gaps or inconsistencies in a body of knowledge. You need to have a sufficiently focused research question to conduct a narrative literature review

Systematic literature review requires more rigorous and well-defined approach compared to most other types of literature review. Systematic literature review is comprehensive and details the timeframe within which the literature was selected. Systematic literature review can be divided into two categories: meta-analysis and meta-synthesis.

When you conduct meta-analysis you take findings from several studies on the same subject and analyze these using standardized statistical procedures. In meta-analysis patterns and relationships are detected and conclusions are drawn. Meta-analysis is associated with deductive research approach.

Meta-synthesis, on the other hand, is based on non-statistical techniques. This technique integrates, evaluates and interprets findings of multiple qualitative research studies. Meta-synthesis literature review is conducted usually when following inductive research approach.

Scoping literature review , as implied by its name is used to identify the scope or coverage of a body of literature on a given topic. It has been noted that “scoping reviews are useful for examining emerging evidence when it is still unclear what other, more specific questions can be posed and valuably addressed by a more precise systematic review.” [1] The main difference between systematic and scoping types of literature review is that, systematic literature review is conducted to find answer to more specific research questions, whereas scoping literature review is conducted to explore more general research question.

Argumentative literature review , as the name implies, examines literature selectively in order to support or refute an argument, deeply imbedded assumption, or philosophical problem already established in the literature. It should be noted that a potential for bias is a major shortcoming associated with argumentative literature review.

Integrative literature review reviews , critiques, and synthesizes secondary data about research topic in an integrated way such that new frameworks and perspectives on the topic are generated. If your research does not involve primary data collection and data analysis, then using integrative literature review will be your only option.

Theoretical literature review focuses on a pool of theory that has accumulated in regard to an issue, concept, theory, phenomena. Theoretical literature reviews play an instrumental role in establishing what theories already exist, the relationships between them, to what degree existing theories have been investigated, and to develop new hypotheses to be tested.

At the earlier parts of the literature review chapter, you need to specify the type of your literature review your chose and justify your choice. Your choice of a specific type of literature review should be based upon your research area, research problem and research methods.  Also, you can briefly discuss other most popular types of literature review mentioned above, to illustrate your awareness of them.

[1] Munn, A. et. al. (2018) “Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach” BMC Medical Research Methodology

  John Dudovskiy

Systematic Reviews: Types of literature review, methods, & resources

• Types of literature review, methods, & resources
• Protocol and registration
• Search strategy
• Medical Literature Databases to search
• Study selection and appraisal
• Data Extraction/Coding/Study characteristics/Results
• Reporting the quality/risk of bias
• Manage citations using RefWorks This link opens in a new window
• GW Box file storage for PDF's This link opens in a new window

Analytical reviews

GUIDELINES FOR HOW TO CARRY OUT AN ANALYTICAL REVIEW OF QUANTITATIVE RESEARCH

Enhancing the QUAlity and Transparency Of health Research (EQUATOR) network. (Tracking and listing over 550 reporting guidelines for various different study types including Randomised trials, Systematic reviews, Study protocols, Diagnostic/prognostic studies, Case reports, Clinical practice guidelines, Animal pre-clinical studies, etc). http://www.equator-network.org/resource-centre/library-of-health-research-reporting/

When comparing therapies :

PRISMA (Guideline on how to perform and write-up a systematic review and/or meta-analysis of the outcomes reported in multiple clinical trials of therapeutic interventions. PRISMA  replaces the previous QUORUM statement guidelines ):  Liberati, A,, Altman, D,, Moher, D, et al. (2009). The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration.  Plos Medicine, 6 (7):e1000100. doi:10.1371/journal.pmed.1000100 

When comparing diagnostic methods :

Checklist for Artificial Intelligence in Medical Imaging (CLAIM). CLAIM is modeled after the STARD guideline and has been extended to address applications of AI in medical imaging that include classification, image reconstruction, text analysis, and workflow optimization. The elements described here should be viewed as a “best practice” to guide authors in presenting their research. Reported in Mongan, J., Moy, L., & Kahn, C. E., Jr (2020). Checklist for Artificial Intelligence in Medical Imaging (CLAIM): A Guide for Authors and Reviewers.  Radiology. Artificial intelligence ,  2 (2), e200029. https://doi.org/10.1148/ryai.2020200029

STAndards for the Reporting of Diagnostic accuracy studies (STARD) Statement. (Reporting guidelines for writing up a study comparing the accuracy of competing diagnostic methods)  http://www.stard-statement.org/

When evaluating clinical practice guidelines :

AGREE Research Trust (ART) (2013).  Appraisal of Guidelines for Research & Evaluation (AGREE-II) . (A 23-item instrument for as sessing th e quality of Clinical Practice Guidelines. Used internationally for evaluating or deciding which guidelines could be recommended for use in practice or to inform health policy decisions.)

National Guideline Clearinghouse Extent of Adherence to Trustworthy Standards (NEATS) Instrument (2019). (A 15-item instrument using scales of 1-5 to evaluate a guideline's adherence to the Institute of Medicine's standard for trustworthy guidelines. It has good external validity among guideline developers and good interrater reliability across trained reviewers.)

When you need to re-analyze individual participant data

If you wish to collect, check, and re-analyze individual participant data (IPD) from clinical trials addressing a particular research question, you should follow the  PRISMA-IPD  guidelines as reported in  Stewart, L.A., Clarke, M., Rovers, M., et al. (2015). Preferred Reporting Items for a Systematic Review and Meta-analysis of Individual Participant Data: The PRISMA-IPD Statement. JAMA, 313(16):1657-1665. doi:10.1001/jama.2015.3656 .

When comparing Randomized studies involving animals, livestock, or food:

O’Connor AM, et al. (2010).  The REFLECT statement: methods and processes of creating reporting guidelines for randomized controlled trials for livestock and food safety by modifying the CONSORT statement.  Zoonoses Public Health. 57(2):95-104. Epub 2010/01/15. doi: 10.1111/j.1863-2378.2009.01311.x. PubMed PMID: 20070653.

Sargeant JM, et al. (2010).  The REFLECT Statement: Reporting Guidelines for Randomized Controlled Trials in Livestock and Food Safety: Explanation and Elaboration.  Zoonoses Public Health. 57(2):105-36. Epub 2010/01/15. doi: JVB1312 [pii] 10.1111/j.1863-2378.2009.01312.x. PubMed PMID: 20070652.

GUIDELINES FOR HOW TO WRITE UP FOR PUBLICATION THE RESULTS OF ONE QUANTITATIVE CLINICAL TRIAL

When reporting the results of a Randomized Controlled Trial :

Consolidated Standards of Reporting Trials (CONSORT) Statement. (2010 reporting guideline for writing up a Randomized Controlled Clinical Trial).  http://www.consort-statement.org . Since updated in 2022, see Butcher, M. A., et al. (2022). Guidelines for Reporting Outcomes in Trial Reports: The CONSORT-Outcomes 2022 Extension . JAMA : the Journal of the American Medical Association, 328(22), 2252–2264. https://doi.org/10.1001/jama.2022.21022

Kilkenny, C., Browne, W. J., Cuthill, I. C., Emerson, M., & Altman, D. G. (2010). Improving bioscience research reporting: The ARRIVE guidelines for reporting animal research. PLoS Biology, 8(6), e1000412–e1000412. https://doi.org/10.1371/journal.pbio.1000412 (A 20-item checklist, following the CONSORT approach, listing the information that published articles reporting research using animals should include, such as the number and specific characteristics of animals used; details of housing and husbandry; and the experimental, statistical, and analytical methods used to reduce bias.)

Narrative reviews

GUIDELINES  FOR HOW TO CARRY OUT  A  NARRATIVE REVIEW / QUALITATIVE RESEARCH /  OBSERVATIONAL STUDIES

Campbell, M. (2020). Synthesis without meta-analysis (SWiM) in systematic reviews: reporting guideline. BMJ, 368. doi: https://doi.org/10.1136/bmj.l6890  (guideline on how to analyse evidence for a narrative review, to provide a recommendation based on heterogenous study types).

Community Preventive Services Task Force (2021).  The Methods Manual for Community Guide Systematic Reviews . (Public Health Prevention systematic review guidelines)

Enhancing the QUAlity and Transparency Of health Research (EQUATOR) network. (Tracking and listing over 550 reporting guidelines for various different study types including Observational studies, Qualitative research, Quality improvement studies, and Economic evaluations). http://www.equator-network.org/resource-centre/library-of-health-research-reporting/

Cochrane Qualitative & Implementation Methods Group. (2019). Training resources. Retrieved from  https://methods.cochrane.org/qi/training-resources . (Training materials for how to do a meta-synthesis, or qualitative evidence synthesis). 

Cornell University Library (2019). Planning worksheet for structured literature reviews. Retrieved 4/8/22 from  https://osf.io/tnfm7/  (offers a framework for a narrative literature review).

Green, B. N., Johnson, C. D., & Adams, A. (2006).  Writing narrative literature reviews for peer-reviewed journals: secrets of the trade . Journal of Chiropractic Medicine, 5(3): 101-117. DOI: 10.1016/ S0899-3467 (07)60142-6.  This is a very good article about what to take into consideration when writing any type of narrative review.

When reviewing observational studies/qualitative research :

STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) statement. (Reporting guidelines for various types of health sciences observational studies).  http://www.strobe-statement.org 

Meta-analysis of Observational Studies in Epidemiology (MOOSE)  http://jama.jamanetwork.com/article.aspx?articleid=192614

RATS Qualitative research systematic review guidelines.  https://www.equator-network.org/reporting-guidelines/qualitative-research-review-guidelines-rats/

Methods/Guidance

Right Review , this decision support website provides an algorithm to help reviewers choose a review methodology from among 41 knowledge synthesis methods.

The Systematic Review Toolbox , an online catalogue of tools that support various tasks within the systematic review and wider evidence synthesis process. Maintained by the UK University of York Health Economics Consortium, Newcastle University NIHR Innovation Observatory, and University of Sheffield School of Health and Related Research.

Institute of Medicine. (2011).  Finding What Works in Health Care: Standards for Systematic Reviews . Washington, DC: National Academies  (Systematic review guidelines from the Health and Medicine Division (HMD) of the U.S. National Academies of Sciences, Engineering, and Medicine (formerly called the Institute of Medicine)).

International Committee of Medical Journal Editors (2022).  Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly work in Medical Journals . Guidance on how to prepare a manuscript for submission to a Medical journal.

Cochrane Handbook of Systematic Reviews of Interventions (International Cochrane Collaboration systematic review guidelines). The various Cochrane review groups comporise around 30,000 physicians around the world working in the disciplines on reviews of interventions with very detailed methods for verifying the validity of the research methods and analysis performed in screened-in Randmized Controlled Clinical Trials. Typically published Cochrane Reviews are the most exhaustive review of the evidence of effectiveness of a particular drug or intervention, and include a statistical meta-analysis. Similar to practice guidelines, Cochrane reviews are periodically revised and updated.

Joanna Briggs Institute (JBI) Manual of Evidence Synthesis . (International systematic review guidelines). Based at the University of Adelaide, South Australia, and collaborating with around 80 academic and medical entities around the world. Unlike Cochrane Reviews that strictly focus on efficacy of interventions, JBI offers a broader, inclusive approach to evidence, to accommodate a range of diverse questions and study designs. The JBI manual provides guidance on how to analyse and include both quantitative and qualitative research.

Cochrane Methods Support Unit, webinar recordings on methodological support questions 

Cochrane Qualitative & Implementation Methods Group. (2019). Training resources. Retrieved from https://methods.cochrane.org/qi/training-resources . (How to do a meta-synthesis, or qualitative evidence synthesis). 

Center for Reviews and Dissemination (University of York, England) (2009).  Systematic Reviews: CRD's guidance for undertaking systematic reviews in health care . (British systematic review guidelines). 

Agency for Health Research & Quality (AHRQ) (2013). Methods guide for effectiveness and comparative effectiveness reviews . (U.S. comparative effectiveness review guidelines)

Hunter, K. E., et al. (2022). Searching clinical trials registers: guide for systematic reviewers.  BMJ (Clinical research ed.) ,  377 , e068791. https://doi.org/10.1136/bmj-2021-068791

Patient-Centered Outcomes Research Institute (PCORI).  The PCORI Methodology Report . (A 47-item methodology checklist for U.S. patient-centered outcomes research. Established under the Patient Protection and Affordable Care Act, PCORI funds the development of guidance on the comparative effectivess of clinical healthcare, similar to the UK National Institute for Clinical Evidence but without reporting cost-effectiveness QALY metrics). 

Canadian Agency for Drugs and Technologies in Health (CADTH) (2019). Grey Matters: a practical tool for searching health-related grey literature. Retrieved from https://www.cadth.ca/resources/finding-evidence/grey-matters . A checklist of N American & international online databases and websites you can use to search for unpublished reports, posters, and policy briefs, on topics including general medicine and nursing, public and mental health, health technology assessment, drug and device regulatory, approvals, warnings, and advisories.

Hempel, S., Xenakis, L., & Danz, M. (2016). Systematic Reviews for Occupational Safety and Health Questions: Resources for Evidence Synthesis. Retrieved 8/15/16 from http://www.rand.org/pubs/research_reports/RR1463.html . NIOSH guidelines for how to carry out a systematic review in the occupational safety and health domain.

A good source for reporting guidelines is the  NLM's  Research Reporting Guidelines and Initiatives .

Grading of Recommendations Assessment, Development and Evaluation (GRADE). (An international group of academics/clinicians working to promote a common approach to grading the quality of evidence and strength of recommendations.) 

Phillips, B., Ball, C., Sackett, D., et al. (2009). Oxford Centre for Evidence Based Medicine: Levels of Evidence. Retrieved 3/20/17 from https://www.cebm.net/wp-content/uploads/2014/06/CEBM-Levels-of-Evidence-2.1.pdf . (Another commonly used criteria for grading the quality of evidence and strength of recommendations, developed in part by EBM guru David Sackett.) 

Systematic Reviews for Animals & Food  (guidelines including the REFLECT statement for carrying out a systematic review on animal health, animal welfare, food safety, livestock, and agriculture)

Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies . Health Information & Libraries Journal, 26(2), 91-108. doi:10.1111/j.1471-1842.2009.00848.x. (Describes 14 different types of literature and systematic review, useful for thinking at the outset about what sort of literature review you want to do.)

Sutton, A., Clowes, M., Preston, L., & Booth, A. (2019). Meeting the review family: exploring review types and associated information retrieval requirements . Health information and libraries journal, 36(3), 202–222. doi:10.1111/hir.12276  (An updated look at different types of literature review, expands on the Grant & Booth 2009 article listed above).

Garrard, J. (2007).  Health Sciences Literature Review Made Easy: The Matrix Method  (2nd Ed.).   Sudbury, MA:  Jones & Bartlett Publishers. (Textbook of health sciences literature search methods).

Zilberberg, M. (2012).  Between the lines: Finding the truth in medical literature . Goshen, MA: Evimed Research Press. (Concise book on foundational concepts of evidence-based medicine).

Lang, T. (2009). The Value of Systematic Reviews as Research Activities in Medical Education . In: Lang, T. How to write, publish, & present in the health sciences : a guide for clinicians & laboratory researchers. Philadelphia : American College of Physicians.  (This book chapter has a helpful bibliography on systematic review and meta-analysis methods)

Brown, S., Martin, E., Garcia, T., Winter, M., García, A., Brown, A., Cuevas H.,  & Sumlin, L. (2013). Managing complex research datasets using electronic tools: a meta-analysis exemplar . Computers, Informatics, Nursing: CIN, 31(6), 257-265. doi:10.1097/NXN.0b013e318295e69c. (This article advocates for the programming of electronic fillable forms in Adobe Acrobat Pro to feed data into Excel or SPSS for analysis, and to use cloud based file sharing systems such as Blackboard, RefWorks, or EverNote to facilitate sharing knowledge about the decision-making process and keep data secure. Of particular note are the flowchart describing this process, and their example screening form used for the initial screening of abstracts).

Brown, S., Upchurch, S., & Acton, G. (2003). A framework for developing a coding scheme for meta-analysis . Western Journal Of Nursing Research, 25(2), 205-222. (This article describes the process of how to design a coded data extraction form and codebook, Table 1 is an example of a coded data extraction form that can then be used to program a fillable form in Adobe Acrobat or Microsoft Access).

Elamin, M. B., Flynn, D. N., Bassler, D., Briel, M., Alonso-Coello, P., Karanicolas, P., & ... Montori, V. M. (2009). Choice of data extraction tools for systematic reviews depends on resources and review complexity .  Journal Of Clinical Epidemiology ,  62 (5), 506-510. doi:10.1016/j.jclinepi.2008.10.016  (This article offers advice on how to decide what tools to use to extract data for analytical systematic reviews).

Riegelman R.   Studying a Study and Testing a Test: Reading Evidence-based Health Research , 6th Edition.  Lippincott Williams & Wilkins, 2012. (Textbook of quantitative statistical methods used in health sciences research).

Rathbone, J., Hoffmann, T., & Glasziou, P. (2015). Faster title and abstract screening? Evaluating Abstrackr, a semi-automated online screening program for systematic reviewers. Systematic Reviews, 480. doi:10.1186/s13643-015-0067-6

Guyatt, G., Rennie, D., Meade, M., & Cook, D. (2015). Users' guides to the medical literature (3rd ed.). New York: McGraw-Hill Education Medical.  (This is a foundational textbook on evidence-based medicine and of particular use to the reviewer who wants to learn about the different types of published research article e.g. "what is a case report?" and to understand what types of study design best answer what types of clinical question).

Glanville, J., Duffy, S., Mccool, R., & Varley, D. (2014). Searching ClinicalTrials.gov and the International Clinical Trials Registry Platform to inform systematic reviews: what are the optimal search approaches? Journal of the Medical Library Association : JMLA, 102(3), 177–183. https://doi.org/10.3163/1536-5050.102.3.007

Ouzzani, M., Hammady, H., Fedorowicz, Z., & Elmagarmid, A. (2016). Rayyan a web and mobile app for systematic reviews.  Systematic Reviews, 5 : 210, DOI: 10.1186/s13643-016-0384-4. http://rdcu.be/nzDM

Kwon Y, Lemieux M, McTavish J, Wathen N. (2015). Identifying and removing duplicate records from systematic review searches. J Med Libr Assoc. 103 (4): 184-8. doi: 10.3163/1536-5050.103.4.004. https://www.ncbi.nlm.nih.gov/pubmed/26512216

Bramer WM, Giustini D, de Jonge GB, Holland L, Bekhuis T. (2016). De-duplication of database search results for systematic reviews in EndNote. J Med Libr Assoc. 104 (3):240-3. doi: 10.3163/1536-5050.104.3.014. Erratum in: J Med Libr Assoc. 2017 Jan;105(1):111. https://www.ncbi.nlm.nih.gov/pubmed/27366130

McGowan J, Sampson M, Salzwedel DM, Cogo E, Foerster V, Lefebvre C. PRESS Peer Review of Electronic Search Strategies: 2015 Guideline Statement. J Clin Epidemiol. 2016;75:40–46. doi: 10.1016/j.jclinepi.2016.01.021 . PRESS is a guideline with a checklist for librarians to critically appraise the search strategy for a systematic review literature search.

Clark, JM, Sanders, S, Carter, M, Honeyman, D, Cleo, G, Auld, Y, Booth, D, Condron, P, Dalais, C, Bateup, S, Linthwaite, B, May, N, Munn, J, Ramsay, L, Rickett, K, Rutter, C, Smith, A, Sondergeld, P, Wallin, M, Jones, M & Beller, E 2020, 'Improving the translation of search strategies using the Polyglot Search Translator: a randomized controlled trial',  Journal of the Medical Library Association , vol. 108, no. 2, pp. 195-207.

Journal articles describing systematic review methods can be searched for in PubMed using this search string in the PubMed search box: sysrev_methods [sb] . 

Software tools for systematic reviews

• Covidence GW in 2019 has bought a subscription to this Cloud based tool for facilitating screening decisions, used by the Cochrane Collaboration. Register for an account.
• NVIVO for analysis of qualitative research NVIVO is used for coding interview data to identify common themes emerging from interviews with several participants. GW faculty, staff, and students may download NVIVO software.
• RedCAP RedCAP is software that can be used to create survey forms for research or data collection or data extraction. It has very detailed functionality to enable data exchange with Electronic Health Record Systems, and to integrate with study workflow such as scheduling follow up reminders for study participants.
• SRDR tool from AHRQ Free, web-based and has a training environment, tutorials, and example templates of systematic review data extraction forms
• RevMan 5 RevMan 5 is the desktop version of the software used by Cochrane systematic review teams. RevMan 5 is free for academic use and can be downloaded and configured to run as stand alone software that does not connect with the Cochrane server if you follow the instructions at https://training.cochrane.org/online-learning/core-software-cochrane-reviews/revman/revman-5-download/non-cochrane-reviews
• Rayyan Free, web-based tool for collecting and screening citations. It has options to screen with multiple people, masking each other.
• GradePro Free, web application to create, manage and share summaries of research evidence (called Evidence Profiles and Summary of Findings Tables) for reviews or guidelines, uses the GRADE criteria to evaluate each paper under review.
• DistillerSR Needs subscription. Create coded data extraction forms from templates.
• EPPI Reviewer Needs subscription. Like DistillerSR, tool for text mining, data clustering, classification and term extraction
• SUMARI Needs subscription. Qualitative data analysis.
• Dedoose Needs subscription. Qualitative data analysis, similar to NVIVO in that it can be used to code interview transcripts, identify word co-occurence, cloud based.
• Meta-analysis software for statistical analysis of data for quantitative reviews SPSS, SAS, and STATA are popular analytical statistical software that include macros for carrying out meta-analysis. Himmelfarb has SPSS on some 3rd floor computers, and GW affiliates may download SAS to your own laptop from the Division of IT website. To perform mathematical analysis of big data sets there are statistical analysis software libraries in the R programming language available through GitHub and RStudio, but this requires advanced knowledge of the R and Python computer languages and data wrangling/cleaning.
• PRISMA 2020 flow diagram The PRISMA Statement website has a page listing example flow diagram templates

GW researchers may want to consider using Refworks to manage citations, and GW Box to store the full text PDF's of review articles. You can also use online survey forms such as Qualtrics, RedCAP, or Survey Monkey, to design and create your own coded fillable forms, and export the data to Excel or one of the qualitative analytical software tools listed above.

Forest Plot Generators

• RevMan 5 the desktop version of the software used by Cochrane systematic review teams. RevMan 5 is free for academic use and can be downloaded and configured to run as stand alone software that does not connect with the Cochrane server if you follow the instructions at https://training.cochrane.org/online-learning/core-software-cochrane-reviews/revman/revman-5-download/non-cochrane-reviews.
• Meta-Essentials a free set of workbooks designed for Microsoft Excel that, based on your input, automatically produce meta-analyses including Forest Plots. Produced for Erasmus University Rotterdam joint research institute.
• Neyeloff, Fuchs & Moreira Another set of Excel worksheets and instructions to generate a Forest Plot. Published as Neyeloff, J.L., Fuchs, S.C. & Moreira, L.B. Meta-analyses and Forest plots using a microsoft excel spreadsheet: step-by-step guide focusing on descriptive data analysis. BMC Res Notes 5, 52 (2012). https://doi-org.proxygw.wrlc.org/10.1186/1756-0500-5-52
• For R programmers instructions are at https://cran.r-project.org/web/packages/forestplot/vignettes/forestplot.html and you can download the R code package from https://github.com/gforge/forestplot
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Systematic Reviews & Evidence Synthesis Methods

Types of reviews.

• Formulate Question
• Find Existing Reviews & Protocols
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• Searching Systematically
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• Managing Results
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Not sure what type of review you want to conduct?

There are many types of reviews ---  narrative reviews ,  scoping reviews , systematic reviews, integrative reviews, umbrella reviews, rapid reviews and others --- and it's not always straightforward to choose which type of review to conduct. These Review Navigator tools (see below) ask a series of questions to guide you through the various kinds of reviews and to help you determine the best choice for your research needs.

• Which review is right for you? (Univ. of Manitoba)
• What type of review is right for you? (Cornell)
• Review Ready Reckoner - Assessment Tool (RRRsAT)
• A typology of reviews: an analysis of 14 review types and associated methodologies. by Grant & Booth
• Meeting the review family: exploring review types and associated information retrieval requirements | Health Info Libr J, 2019

Label	Description	Search	Appraisal	Synthesis	Analysis
Critical Review	Aims to demonstrate writer has extensively researched literature and critically evaluated its quality. Goes beyond mere description to include degree of analysis and conceptual innovation. Typically results in hypothesis or model	Seeks to identify most significant items in the field	No formal quality assessment. Attempts to evaluate according to contribution	Typically narrative, perhaps conceptual or chronological	Significant component: seeks to identify conceptual contribution to embody existing or derive new theory
Literature Review	Generic term: published materials that provide examination of recent or current literature. Can cover wide range of subjects at various levels of completeness and comprehensiveness. May include research findings	May or may not include comprehensive searching	May or may not include quality assessment	Typically narrative	Analysis may be chronological, conceptual, thematic, etc.
Mapping review/ systematic map	Map out and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in research literature	Completeness of searching determined by time/scope constraints	No formal quality assessment	May be graphical and tabular	Characterizes quantity and quality of literature, perhaps by study design and other key features. May identify need for primary or secondary research
Meta-analysis	Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results	Aims for exhaustive, comprehensive searching. May use funnel plot to assess completeness	Quality assessment may determine inclusion/exclusion and/or sensitivity analyses	Graphical and tabular with narrative commentary	Numerical analysis of measures of effect assuming absence of heterogeneity
Mixed studies review/mixed methods review	Refers to any combination of methods where one significant component is a literature review (usually systematic). Within a review context it refers to a combination of review approaches for example combining quantitative with qualitative research or outcome with process studies	Requires either very sensitive search to retrieve all studies or separately conceived quantitative and qualitative strategies	Requires either a generic appraisal instrument or separate appraisal processes with corresponding checklists	Typically both components will be presented as narrative and in tables. May also employ graphical means of integrating quantitative and qualitative studies	Analysis may characterise both literatures and look for correlations between characteristics or use gap analysis to identify aspects absent in one literature but missing in the other
Overview	Generic term: summary of the [medical] literature that attempts to survey the literature and describe its characteristics	May or may not include comprehensive searching (depends whether systematic overview or not)	May or may not include quality assessment (depends whether systematic overview or not)	Synthesis depends on whether systematic or not. Typically narrative but may include tabular features	Analysis may be chronological, conceptual, thematic, etc.
Qualitative systematic review/qualitative evidence synthesis	Method for integrating or comparing the findings from qualitative studies. It looks for ‘themes’ or ‘constructs’ that lie in or across individual qualitative studies	May employ selective or purposive sampling	Quality assessment typically used to mediate messages not for inclusion/exclusion	Qualitative, narrative synthesis	Thematic analysis, may include conceptual models
Rapid review	Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research	Completeness of searching determined by time constraints	Time-limited formal quality assessment	Typically narrative and tabular	Quantities of literature and overall quality/direction of effect of literature
Scoping review	Preliminary assessment of potential size and scope of available research literature. Aims to identify nature and extent of research evidence (usually including ongoing research)	Completeness of searching determined by time/scope constraints. May include research in progress	No formal quality assessment	Typically tabular with some narrative commentary	Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review
State-of-the-art review	Tend to address more current matters in contrast to other combined retrospective and current approaches. May offer new perspectives on issue or point out area for further research	Aims for comprehensive searching of current literature	No formal quality assessment	Typically narrative, may have tabular accompaniment	Current state of knowledge and priorities for future investigation and research
Systematic review	Seeks to systematically search for, appraise and synthesis research evidence, often adhering to guidelines on the conduct of a review	Aims for exhaustive, comprehensive searching	Quality assessment may determine inclusion/exclusion	Typically narrative with tabular accompaniment	What is known; recommendations for practice. What remains unknown; uncertainty around findings, recommendations for future research
Systematic search and review	Combines strengths of critical review with a comprehensive search process. Typically addresses broad questions to produce ‘best evidence synthesis’	Aims for exhaustive, comprehensive searching	May or may not include quality assessment	Minimal narrative, tabular summary of studies	What is known; recommendations for practice. Limitations
Systematized review	Attempt to include elements of systematic review process while stopping short of systematic review. Typically conducted as postgraduate student assignment	May or may not include comprehensive searching	May or may not include quality assessment	Typically narrative with tabular accompaniment   Reproduced from Grant MJ, Booth A. A typology of reviews: an analysis of 14 review types and associated methodologies . Health Info Libr J. 2009 Jun;26(2):91-108. doi: 10.1111/j.1471-1842.2009.00848.x Last Updated: Jun 26, 2024 3:15 PM URL: https://guides.lib.utexas.edu/systematicreviews May 5-8, 2024 Past Conferences A Non-Systematic Literature Review of Literature Reviews: Evaluation of Methods Implemented and Language Used to Describe Systematic and Non-Systematic Literature Reviews Brown AE 1 , Los AK 1 , Goldsmith-Martin G 1 , Phalguni A 1 , Bowes K 1 , Briggs JA 1 , Bajko P 1 , Kilty RLH 1 , Khankhel ZS 2 1 Genesis Research Group, Newcastle upon Tyne, Tyne and Wear, UK, 2 Genesis Research Group, Hoboken, NJ, USA OBJECTIVES: Systematic literature reviews (SLRs) are a widely used research tool with established best practices. Non-systematic literature reviews (nSLRs) encompass a range of review types and implement varying approaches to searching, screening, and data extraction. We sought to collate established guidance for SLRs/nSLRs and to understand whether there was consistency in the language and methods used to describe and conduct published SLRs/nSLRs. METHODS: MEDLINE (via PubMed) was searched (5 Dec 2023) to identify SLRs/nSLRs published on any topic; records were restricted to those published in English, within the prior week. Title/abstract (TIAB) screening was conducted by a single researcher; includes were tagged as either SLR or nSLR. A random sample of TIAB-level includes (100 SLRs, 100 nSLRs) underwent full-text screening, involving high-level data extraction and conducted by two independent researchers. Separate searches of established evidence synthesis organizations (i.e. Cochrane, University of York, PRISMA), a selection of universities, and other research organizations were also conducted to collate recommendations or established guidance for conducting SLRs and nSLRs. RESULTS: 1,233/1,271 TIABs identified from MEDLINE met the inclusion criteria. Of the 100 reviews defined by authors as SLRs, 93 followed established guidance; 7 did not clearly report whether established guidance for conducting SLRs was followed. Of the 100 nSLRs, authors defined their research using varying terms: review (n=55), scoping review (n=19), literature review (n=11), narrative review (n=10), comprehensive review (n=2), rapid review (n=1), structured integrative review (n=1), and tutorial review (n=1). Upon review of methods implemented in the nSLRs, 12 utilized methods sufficient for SLR definition; the remaining either leveraged elements of SLR methods or did not clearly report these details. Study Approaches Topic Subcategory Literature Review & Synthesis No Additional Disease & Conditions/Specialized Treatment Areas Locations and Hours UCLA Library Research Guides Biomedical Library Guides Systematic Reviews Types of Literature Reviews What Makes a Systematic Review Different from Other Types of Reviews? Planning Your Systematic Review Database Searching Creating the Search Search Filters and Hedges Grey Literature Managing and Appraising Results Further Resources Reproduced from Grant, M. J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91–108. doi:10.1111/j.1471-1842.2009.00848.x Aims to demonstrate writer has extensively researched literature and critically evaluated its quality. Goes beyond mere description to include degree of analysis and conceptual innovation. Typically results in hypothesis or mode Seeks to identify most significant items in the field No formal quality assessment. Attempts to evaluate according to contribution Typically narrative, perhaps conceptual or chronological Significant component: seeks to identify conceptual contribution to embody existing or derive new theory Generic term: published materials that provide examination of recent or current literature. Can cover wide range of subjects at various levels of completeness and comprehensiveness. May include research findings May or may not include comprehensive searching May or may not include quality assessment Typically narrative Analysis may be chronological, conceptual, thematic, etc. Mapping review/ systematic map Map out and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in research literature Completeness of searching determined by time/scope constraints No formal quality assessment May be graphical and tabular Characterizes quantity and quality of literature, perhaps by study design and other key features. May identify need for primary or secondary research Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results Aims for exhaustive, comprehensive searching. May use funnel plot to assess completeness Quality assessment may determine inclusion/ exclusion and/or sensitivity analyses Graphical and tabular with narrative commentary Numerical analysis of measures of effect assuming absence of heterogeneity Refers to any combination of methods where one significant component is a literature review (usually systematic). Within a review context it refers to a combination of review approaches for example combining quantitative with qualitative research or outcome with process studies Requires either very sensitive search to retrieve all studies or separately conceived quantitative and qualitative strategies Requires either a generic appraisal instrument or separate appraisal processes with corresponding checklists Typically both components will be presented as narrative and in tables. May also employ graphical means of integrating quantitative and qualitative studies Analysis may characterise both literatures and look for correlations between characteristics or use gap analysis to identify aspects absent in one literature but missing in the other Generic term: summary of the [medical] literature that attempts to survey the literature and describe its characteristics May or may not include comprehensive searching (depends whether systematic overview or not) May or may not include quality assessment (depends whether systematic overview or not) Synthesis depends on whether systematic or not. Typically narrative but may include tabular features Analysis may be chronological, conceptual, thematic, etc. Method for integrating or comparing the findings from qualitative studies. It looks for ‘themes’ or ‘constructs’ that lie in or across individual qualitative studies May employ selective or purposive sampling Quality assessment typically used to mediate messages not for inclusion/exclusion Qualitative, narrative synthesis Thematic analysis, may include conceptual models Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research Completeness of searching determined by time constraints Time-limited formal quality assessment Typically narrative and tabular Quantities of literature and overall quality/direction of effect of literature Preliminary assessment of potential size and scope of available research literature. Aims to identify nature and extent of research evidence (usually including ongoing research) Completeness of searching determined by time/scope constraints. May include research in progress No formal quality assessment Typically tabular with some narrative commentary Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review Tend to address more current matters in contrast to other combined retrospective and current approaches. May offer new perspectives Aims for comprehensive searching of current literature No formal quality assessment Typically narrative, may have tabular accompaniment Current state of knowledge and priorities for future investigation and research Seeks to systematically search for, appraise and synthesis research evidence, often adhering to guidelines on the conduct of a review Aims for exhaustive, comprehensive searching Quality assessment may determine inclusion/exclusion Typically narrative with tabular accompaniment What is known; recommendations for practice. What remains unknown; uncertainty around findings, recommendations for future research Combines strengths of critical review with a comprehensive search process. Typically addresses broad questions to produce ‘best evidence synthesis’ Aims for exhaustive, comprehensive searching May or may not include quality assessment Minimal narrative, tabular summary of studies What is known; recommendations for practice. Limitations Attempt to include elements of systematic review process while stopping short of systematic review. Typically conducted as postgraduate student assignment May or may not include comprehensive searching May or may not include quality assessment Typically narrative with tabular accompaniment What is known; uncertainty around findings; limitations of methodology Specifically refers to review compiling evidence from multiple reviews into one accessible and usable document. Focuses on broad condition or problem for which there are competing interventions and highlights reviews that address these interventions and their results Identification of component reviews, but no search for primary studies Quality assessment of studies within component reviews and/or of reviews themselves Graphical and tabular with narrative commentary What is known; recommendations for practice. What remains unknown; recommendations for future research << Previous: Home Next: Planning Your Systematic Review >> Last Updated: Apr 17, 2024 2:02 PM URL: https://guides.library.ucla.edu/systematicreviews Case report Open access Published: 28 June 2024 Pseudomyxoma peritonei leading to “jelly belly” abdomen: a case report and review of the literature Priyanka Garg   ORCID: orcid.org/0000-0003-0336-4750 1 , Nikhil Garg 2 , Sameer Peer 3 , Deepika Chholak 1 & Manjit Kaur 4   Journal of Medical Case Reports volume  18 , Article number:  296 ( 2024 ) Cite this article 71 Accesses Metrics details Pseudomyxoma peritonei is an infrequent condition with a global annual incidence of only one to two cases per million people. Mucinous neoplasms, widespread intraperitoneal implants, and mucinous ascites characterize it. Currently, most clinicians misdiagnose this condition, which leads to delayed management. Case presentation A 44-year-old North Indian female presented with a 1.5-month history of an abdominal lump. Physical examination revealed a sizeable abdominopelvic mass at 36 weeks. Contrast-enhanced computed tomography showed a massive multiloculated right ovarian cystic mass measuring 28 × 23 × 13 cm with mild ascites and elevated carcinoembryonic antigen levels (113.75 ng/ml). A provisional diagnosis of ovarian mucinous neoplasm was made, for which the patient underwent laparotomy. Intraoperatively, there were gross mucinous ascites, along with a large, circumscribed, ruptured right ovarian tumor filled with gelatinous material. The appendicular lump was also filled with mucinous material along with the omentum, ascending colon, right lateral aspect of the rectum, splenic surface, and small bowel mesentery. Cytoreductive surgery was performed along with an oncosurgeon, including total abdominal hysterectomy with bilateral salpingoophorectomy, omentectomy, right hemicolectomy, lower anterior resection, ileo-transverse stapled anastomosis with proximal ileal loop diversion stoma, excision of multiple peritoneal gelatinous implants, and peritoneal lavage. Histopathology and immunohistochemistry confirmed the presence of intestinal-type mucinous carcinoma. Postoperatively, the patient was given six cycles of chemotherapy. She tolerated it without any specific morbidity and had an uneventful recovery. Postoperative follow-up at 15 months revealed normal tumor marker levels and abdominal computed tomography findings and no signs suggestive of local recurrence or distal metastases. Conclusions Pseudomyxoma peritonei is a rare disease that is frequently misdiagnosed in the preoperative phase. Therefore, radiologists and clinicians should maintain a high index of suspicion for accurate diagnosis and multidisciplinary management. Peer Review reports Introduction Pseudomyxoma peritonei (PMP) is a rare condition caused by primary mucinous tumors arising from different locations, usually the appendix or ovary; other rare sites include the gallbladder, stomach, colorectum, fallopian tube, urachus, lung, and breast. It is characterized by mucin production in the abdominal cavity and, if left untreated, can compress adjacent vital organs. The term “PMP” was first given by Werth in 1884, and the current incidence is estimated to be one to two cases per million per year [ 1 ]. With a mean incidence at the age of 53 years, PMP is more prevalent in women (male-to-female ratio, 9:11) [ 2 ]. The clinical features are often nonspecific and may manifest as an inexplicable increase in abdominal girth, abdominal pain, ascites, unilateral or bilateral ovarian tumors, bowel obstruction, or appendicitis-like symptoms. The initial diagnostic modality is ultrasonography (USG), followed by computed tomography (CT) or magnetic resonance imaging (MRI) of the abdomen/pelvis. Most of the time, however, the diagnosis is often missed during preoperative evaluation, and the tumor is discovered accidentally during surgery [ 3 ]. The serum tumor markers cancer antigen (CA) 19–9 and carcinoembryonic antigen (CEA) aid in diagnosis and have prognostic value [ 2 ]. The definitive management consists of complete cytoreductive surgery (CRS) to achieve macroscopic tumor removal, followed by intraperitoneal or systemic chemotherapy to treat microscopic residual disease [ 4 ]. However, no standard guidelines are available for the treatment of these patients. In March 2018, the National Comprehensive Cancer Network (NCCN) published a guideline stating that, in recent research, completion of CRS was associated with improving patients’ overall survival, while hyperthermic intraoperative peritoneal chemotherapy (HIPEC) did not [ 5 ]. Hence, long-term survival and complete cure have limited expectations [ 5 ]. Thus, more robust data need to be generated to provide a less harmful therapeutic approach in an individualized manner along with palliative therapy for those who are ineligible candidates for surgery. PMP should be managed with a multidisciplinary team approach involving a gynecologist, oncosurgeon, radiologist, pathologist, and medical oncologist. We present one such rare case of PMP in a female who was missed on imaging and diagnosed intraoperatively. She was successfully managed with surgical debulking plus chemotherapy. To the best of our knowledge, this is one of the few case reports published in India that has highlighted such surgeries and generated awareness in favor of them. A 44-year-old North Indian (para 2, live 2) patient with a previous cesarean section came to the gynecology out-patient department (OPD) with complaints of a lump in the abdomen for the last 1.5 months. Initially, the size of the lump reached the umbilicus, which suddenly increased to the xiphisternum. There was associated abdominal discomfort but no nausea, vomiting, or fever. Her previous medical and family history was unremarkable. On general examination, the patient was, on average, built and afebrile, with no evidence of anemia, jaundice, cyanosis, lymphadenopathy, clubbing, or weight loss. She had normal bladder and bowel function. Her menstrual cycles were regular with normal flow. An abdominal examination revealed a large abdominopelvic mass corresponding to the epigastrium for up to 36 weeks. It was cystic in consistency with a smooth surface, non-tender, and slightly mobile in the transverse plane. The lack of shifting dullness negated the presence of ascites. A per-vaginal examination confirmed an abdominopelvic mass of 36 weeks in size with a normal external vulva and cervix. The uterus could not be appreciated separately. Ultrasound revealed a large abdominopelvic mass with internal septations reaching the epigastrium. The uterus was normal in size, with mild ascites and bilateral adnexa obscured by the mass. On further evaluation, contrast-enhanced computed tomography (CECT) was performed to characterize the mass, which showed a large multiloculated abdominopelvic cystic mass measuring 28 × 23 × 13 cm with the right ovary not seen separately, suggesting a right ovarian origin. The uterus and left ovary were normal and displaced by the mass. Mild ascites was present. Multiple thick enhancing septa were also observed within the mass with no solid component ( Fig.  1 ). Her CA 125 and CA 19–9 levels were normal (35.4 U/ml and 18.85 U/ml, respectively). However, her CEA level was elevated to 113.75 ng/ml (normal range 0–3 ng/ml). A provisional diagnosis of a right ovarian mucinous tumor was made, and the patient underwent exploratory laparotomy after providing informed consent. Intraoperative findings revealed gelatinous material filling the entire abdominal cavity and pelvis. A large, circumscribed, ruptured tumor arose from the right ovary filled with gelatinous material. Axial contrast-enhanced computed tomography images of the abdomen and pelvis. The arrows point toward ( A ) a multiseptated abdominopelvic mass lesion with enhancing septations and relatively hyperdense ascites surrounding the mass; B scalloping of the anterior margin of the liver (arrow) caused by the ascitic fluid; C displacement of the small bowel loops (arrow) by the abdominopelvic mass and ascitic fluid, suggesting a mass effect in coronal reconstruction; and D enhancing appendix engulfed within the abdominopelvic mass (arrow) in axial contrast-enhanced computed tomography There were mucinous deposits on the anterior surface of the normal-sized uterus and left ovary. The appendicular lump was also filled with gelatinous material. Multiple gelatinous nodules were present on the omentum, along the ascending colon, right lateral aspect of the rectum, splenic surface, and small bowel mesentery. The oncosurgeon was called intraoperatively, and we performed CRS, including total abdominal hysterectomy with bilateral salpingoophorectomy, total omentectomy, right hemicolectomy, lower anterior resection, ileo-transverse stapled anastomosis with proximal ileal loop diversion stoma, excision of multifocal peritoneal mucinous implants, and peritoneal lavage (Fig.  2 ). Surgical specimens were subjected to histopathological and immunohistochemical (IHC) examination. Microscopically, the tumor cells were arranged as back-to-back glands, papillae, and cysts lined by mucinous columnar epithelium (intestinal type), with oval to elongated nuclei, a high nucleocytoplasmic ratio, and vesicular nuclei. Stromal infiltration by tumors was noted in the form of nests, irregularly shaped glands, and cords of tumor cells. Abundant extravasated mucin was also observed, revealing mucinous carcinoma of the intestinal type (Fig.  3 ). On IHC, the tumor cells were CK20+ , CDX2+ , and CK7−, which indicate mucinous neoplasms of the intestinal type. The patient was given six cycles of chemotherapy with carboplatin and paclitaxel. She had an uneventful recovery (as of publication) for 15 months following the operation, with normal tumor marker levels and abdominal CT findings and no signs of local recurrence or distal metastases. A Postoperative images showing yellow gelatinous material and B total abdominal hysterectomy with bilateral salpingoophorectomy, omentectomy, and right hemicolectomy with lower anterior resection Low-power view of a section of A ovary B , C omentum, and D colon showing mucin deposits containing tumor cells (hematoxylin and eosin, 10×) PMP is a poorly understood clinical condition characterized by intra-abdominal mucin accumulation secondary to the proliferation of malignant mucin-secreting cells on the peritoneal surface. In contrast to most malignancies, it rarely spreads via the hematogenous or lymphatic system [ 6 ]. Hence, there is nowhere for extracellular mucin to drain, which accumulates significantly in the abdominal cavity and causes the so-called jelly belly abdomen. It was first described by Carl Von Rokitansky in 1842, but the term was used in 1884 in association with a mucinous carcinoma of the ovary [ 7 ]. Later, in 1901, Franckel described PMP as an appendiceal cystic tumor [ 8 ]. The origin of PMP is still debatable. Most authors agree that PMP develops mainly in the appendix in men, and mounting evidence supports a similar genesis in women. Worldwide, 30–50% of women have simultaneous ovarian and appendiceal mucinous tumors [ 9 ]. However, immunohistochemical and molecular genetic approaches support the concept that most ovarian tumors in women are metastatic to a perforated appendiceal mucinous tumor. This notion is supported by our case, in which histological examination of the oophorectomy specimen revealed a pattern consistent with intestinal/appendicular origin. The diagnosis of PMP is often challenging for clinicians, as the majority of patients remain asymptomatic or present with nonspecific clinical features, such as pain in the abdomen, nausea, vomiting, abdominal distention (as seen in our case), or mass. Approximately one-third of female patients present with an ovarian tumor, as observed in our case [ 10 ]. The excessive accumulation of mucin in the peritoneal cavity can compress adjacent structures, leading to bowel obstruction and malnutrition. Touloumis Z et al . reported a case of PMP in a 71-year-old patient who presented with intermittent diarrhea without any other symptoms [ 6 ]. Imaging studies are also not very helpful in reaching the diagnosis. USG is the initial investigation that may show highly echogenic ascitic fluid with immobile echogenic septations and a marked laminated appearance (onion-skin effect), reflecting the concentric layering of mucin, typical of gelatinous material [ 4 ]. The gold standard for imaging is CECT. The usual appearance includes areas of low attenuation, with islands of more significant attenuation resulting from solid elements within the mucinous material. Classically, “scalloping” of visceral surfaces, particularly of the liver and spleen, distinguishes mucinous from fluid ascites [ 5 ]. However, most cases are discovered incidentally during laparoscopy or laparotomy [ 11 ]. Mathur S et al . reported the case of a 27-year-old patient who was incidentally diagnosed with disseminated PMP at the time of a cesarean section [ 3 ]. According to the study conducted by Jarvinen and Lepisto, only 28% of patients underwent primary surgery for suspected PMP. The most frequent preoperative diagnosis is appendicitis, gynecological cancer, or ovarian tumor, as in our case, where the diagnosis of PMP was missed on imaging [ 3 ]. Tumor markers such as CEA, CA 19–9, and CA-125 are associated with PMP. CEA is a beneficial prognostic marker during diagnosis and postoperative surveillance [ 2 ]. Preoperative elevation of serum markers indicates aggressive disease and a high chance of recurrence. Canbay et al . noted that preoperative CEA levels can predict disease severity, surgical success, and overall survival in patients treated with CRS and hyperthermic intraoperative peritoneal chemotherapy (HIPEC) [ 12 ]. The definitive diagnosis mandates the presence of a mucinous neoplastic cells/epithelium and diffuse intra-abdominal mucin [ 13 ]. Patients without epithelium were considered to have mucinous ascites. Epithelial glandular cells must be present in the mucin pool on histopathology to confirm the diagnosis of PMP. The biopsy of our patient concurred. The Peritoneal Surface Oncology Group International (PSOGI) pathologic categorization for PMP now uses distinct nomenclature for treatment selection, as presented in Table  1 . Appendiceal adenocarcinomas are classified into three histological categories. The most frequent form, mucinous, produces a large amount of mucin. The less prevalent intestinal or colonic form (our case) closely resembles colon adenocarcinomas. Signet ring cell adenocarcinoma is a rare and aggressive cancer with a poor prognosis [ 2 , 15 ]. Traditionally, the management of PMP includes repeated drainage of gelatinous ascites or serial debulking surgeries involving the removal of the primary tumor and mucinous ascites. However, repeat surgical procedures have become increasingly difficult due to adhesions and fibrous scar tissue formation [ 16 ]. These patients eventually die due to severe malnutrition, intestinal obstruction, or surgical complications. Recent studies support the idea that combined cytoreductive surgery with intraperitoneal chemotherapy (IPEC) should be the standard of care because it has improved survival rates. The 5-year survival rate of patients with CRS and IPEC for low-grade disease is 60–100%, whereas for high-grade disease, it is 0–60% [ 16 ]. CRS aims to eliminate as many macroscopic illnesses as possible. Sugarbaker’s protocol is commonly used for peritonectomy procedures, which may include anterior parietal peritonectomy, total omentectomy, splenectomy, distal pancreatectomy, right and left subphrenic peritonectomy, Glisson’s capsule removal, pelvic peritonectomy, cholecystectomy, and visceral resections such as rectosigmoidectomy, right colectomy, total abdominal colectomy, and hysterectomy with bilateral salpingo-oophorectomy and small bowel resection [ 11 ]. This system is supplemented with IPEC, which targets microscopic residual disease and free neoplastic cells in the peritoneal cavity. Heated/hyperthermic IPEC (HIPEC) can be utilized intraoperatively or early postoperatively [early postoperative intraperitoneal chemotherapy (EPIC)], comparable to peritoneal dialysis. According to a study by Sorensen et al ., there appears to be no difference in survival rates between the two IPEC procedures [ 17 ]. The treatment plan for PMP should aim for full cytoreduction to avoid recurrence or progression. This method is currently being used in numerous centers worldwide, with encouraging results, and appears to be gaining traction compared with traditional serial debulking. However, not all situations are appropriate for this strategy; every center or surgeon is not equipped to perform IPEC, and sometimes, patients might be medically unfit to receive these treatments safely. A randomized study by Verwaal revealed that patients involved in six or more abdominal cavity regions achieved minimal improvement in survival following CRS and intraoperative HIPEC [ 18 ]. Therefore, debulking surgeries alone are still being performed and have an overall survival rate of approximately 50% [ 19 ]. Additionally, currently, there is no consensus regarding the role of CRS and HIPEC treatment for more aggressive histological variations in PMP. Consequently, they provide evidence favoring systemic chemotherapy as the standard of care for such patients [ 20 ]. Per the retrospective research by Shapiro J et al ., patients considered inadequate candidates for CRS and/or HIPEC therapy benefited from extended disease remission of 7.6 months with contemporary systemic chemotherapy [ 21 ]. In another published review of consensus statements and guidelines by the PSOGI expert panel, neoadjuvant or adjuvant systemic chemotherapy can be considered in patients with low-grade PMP and high-grade PMP with signet ring cells. When required, fluoropyrimidine in conjunction with an alkylating drug (such as oxaliplatin) is advised [ 22 ]. Currently, there is no standard systemic chemotherapy regimen, and we are unaware of any prospective clinical trials in this patient cohort that involve contemporary systemic chemotherapy and/or biologic therapy. The patient in the present study was treated with CRS, which consisted of hysterectomy with bilateral salpingo‑oophorectomy, omentectomy, right hemicolectomy, lower anterior resection, ileo-transverse stapled anastomosis with proximal ileal loop diversion stoma, excision of multiple peritoneal mucinous implants, and peritoneal lavage. Since HIPEC was not available in our center, the patient was given six cycles of postoperative systemic chemotherapy, and she has been tumor-free to date. Finally, PMP may relapse despite CRS and chemotherapy (HIPEC, IPEC, or systemic), mainly if the disease is diagnosed at an advanced stage. Tumor marker assessment and routine postoperative CT scans should be utilized to monitor any recurrence. PMP is a rare condition that causes significant morbidity and mortality if left untreated. The diagnosis is often missed, resulting in delayed management. Radiologists and clinicians should maintain a high index of suspicion for timely diagnosis and management. CRS plus IPEC is the standard of care for these patients and can significantly improve survival but is associated with considerable morbidity. Furthermore, it is crucial that the management of PMP be individualized because some patients may benefit more from debulking alone than from CRS combined with IPEC/systemic therapy or vice versa. Additional research into chemotherapy schedules and patient selection may shed light on other strategies to reduce morbidity and increase survival associated with this disease. More prospective trials should be conducted to formulate evidence-based guidelines for managing such patients. 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Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, Bathinda, Punjab, 151001, India Priyanka Garg & Deepika Chholak Department of Surgical Oncology, All India Institute of Medical Sciences, Bathinda, Punjab, 151001, India Nikhil Garg Department of Radiology, All India Institute of Medical Sciences, Bathinda, Punjab, 151001, India Sameer Peer Department of Pathology, All India Institute of Medical Sciences, Bathinda, Punjab, 151001, India Manjit Kaur You can also search for this author in PubMed   Google Scholar Contributions PG, NG, and DC treated the patient. PG was involved in writing the manuscript and obtaining consent from the patient. The SP was involved in the patient’s radiological imaging. MK was involved in the patient’s histopathological diagnosis. All the authors have read and approved the final manuscript. Corresponding author Correspondence to Priyanka Garg . Ethics declarations Ethics approval and consent to participate. This study did not involve animal or human experiments. The patient consented to the use of her data for this case report. Consent for publication Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal. Competing interests The authors declare that they have no competing interests. The authors have no association with financial or nonfinancial organizations. Additional information Publisher’s note. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 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Subscribe to receive issue release notifications and newsletters from MDPI journals Communicative Sciences and Disorders Online Learners: Quick Links ASHA Journals Research Tip 1: Define the Research Question Reference Resources Evidence Summaries & Clinical Guidelines Drug Information Health Data & Statistics Patient/Consumer Facing Materials Images/Streaming Video Database Tutorials Crafting a Search Cited Reference Searching Research Tip 4: Find Grey Literature Research Tip 5: Save Your Work Cite and Manage Your Sources Critical Appraisal What are Literature Reviews? Conducting & Reporting Systematic Reviews Finding Systematic Reviews Tutorials & Tools for Literature Reviews Point of Care Tools (Mobile Apps) Choosing a Review Type For guidance related to choosing a review type, see: "What Type of Review is Right for You?" - Decision Tree (PDF) This decision tree, from Cornell University Library, highlights key difference between narrative, systematic, umbrella, scoping and rapid reviews. Reviewing the literature: choosing a review design Noble, H., & Smith, J. (2018). Reviewing the literature: Choosing a review design. Evidence Based Nursing, 21(2), 39–41. https://doi.org/10.1136/eb-2018-102895 What synthesis methodology should I use? A review and analysis of approaches to research synthesis Schick-Makaroff, K., MacDonald, M., Plummer, M., Burgess, J., & Neander, W. (2016). What synthesis methodology should I use? A review and analysis of approaches to research synthesis. AIMS Public Health, 3 (1), 172-215. doi:10.3934/publichealth.2016.1.172 More information less... ABSTRACT: Our purpose is to present a comprehensive overview and assessment of the main approaches to research synthesis. We use "research synthesis" as a broad overarching term to describe various approaches to combining, integrating, and synthesizing research findings. Right Review - Decision Support Tool Not sure of the most suitable review method? Answer a few questions and be guided to suitable knowledge synthesis methods. Updated in 2022 and featured in the Journal of Clinical Epidemiology 10.1016/j.jclinepi.2022.03.004 Types of Evidence Synthesis / Literature Reviews Literature reviews are comprehensive summaries and syntheses of the previous research on a given topic.  While narrative reviews are common across all academic disciplines, reviews that focus on appraising and synthesizing research evidence are increasingly important in the health and social sciences.   Most evidence synthesis methods use formal and explicit methods to identify, select and combine results from multiple studies, making evidence synthesis a form of meta-research.   The review purpose, methods used and the results produced vary among different kinds of literature reviews; some of the common types of literature review are detailed below. Common Types of Literature Reviews 1 Narrative (literature) review. A broad term referring to reviews with a wide scope and non-standardized methodology Search strategies, comprehensiveness of literature search, time range covered and method of synthesis will vary and do not follow an established protocol Integrative Review A type of literature review based on a systematic, structured literature search Often has a broadly defined purpose or review question Seeks to generate or refine and theory or hypothesis and/or develop a holistic understanding of a topic of interest Relies on diverse sources of data (e.g. empirical, theoretical or methodological literature; qualitative or quantitative studies) Systematic Review Systematically and transparently collects and categorize existing evidence on a question of scientific, policy or management importance Follows a research protocol that is established a priori Some sub-types of systematic reviews include: SRs of intervention effectiveness, diagnosis, prognosis, etiology, qualitative evidence, economic evidence, and more. Time-intensive and often takes months to a year or more to complete  The most commonly referred to type of evidence synthesis; sometimes confused as a blanket term for other types of reviews Meta-Analysis Statistical technique for combining the findings from disparate quantitative studies Uses statistical methods to objectively evaluate, synthesize, and summarize results Often conducted as part of a systematic review Scoping Review Systematically and transparently collects and categorizes existing evidence on a broad question of scientific, policy or management importance Seeks to identify research gaps, identify key concepts and characteristics of the literature and/or examine how research is conducted on a topic of interest Useful when the complexity or heterogeneity of the body of literature does not lend itself to a precise systematic review Useful if authors do not have a single, precise review question May critically evaluate existing evidence, but does not attempt to synthesize the results in the way a systematic review would  May take longer than a systematic review Rapid Review Applies a systematic review methodology within a time-constrained setting Employs methodological "shortcuts" (e.g., limiting search terms and the scope of the literature search), at the risk of introducing bias Useful for addressing issues requiring quick decisions, such as developing policy recommendations Umbrella Review Reviews other systematic reviews on a topic Often defines a broader question than is typical of a traditional systematic review Most useful when there are competing interventions to consider 1. Adapted from: Eldermire, E. (2021, November 15). A guide to evidence synthesis: Types of evidence synthesis. Cornell University LibGuides. https://guides.library.cornell.edu/evidence-synthesis/types Nolfi, D. (2021, October 6). Integrative Review: Systematic vs. Scoping vs. Integrative. Duquesne University LibGuides. https://guides.library.duq.edu/c.php?g=1055475&p=7725920 Delaney, L. (2021, November 24). Systematic reviews: Other review types. UniSA LibGuides. https://guides.library.unisa.edu.au/SystematicReviews/OtherReviewTypes Further Reading: Exploring Different Types of Literature Reviews A typology of reviews: An analysis of 14 review types and associated methodologies Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26 (2), 91-108. doi:10.1111/j.1471-1842.2009.00848.x More information less... ABSTRACT: The expansion of evidence-based practice across sectors has lead to an increasing variety of review types. However, the diversity of terminology used means that the full potential of these review types may be lost amongst a confusion of indistinct and misapplied terms. The objective of this study is to provide descriptive insight into the most common types of reviews, with illustrative examples from health and health information domains. Clarifying differences between review designs and methods Gough, D., Thomas, J., & Oliver, S. (2012). Clarifying differences between review designs and methods. Systematic Reviews, 1 , 28. doi:10.1186/2046-4053-1-28 More information less... ABSTRACT: This paper argues that the current proliferation of types of systematic reviews creates challenges for the terminology for describing such reviews....It is therefore proposed that the most useful strategy for the field is to develop terminology for the main dimensions of variation. Are we talking the same paradigm? Considering methodological choices in health education systematic review Gordon, M. (2016). Are we talking the same paradigm? Considering methodological choices in health education systematic review. Medical Teacher, 38 (7), 746-750. doi:10.3109/0142159X.2016.1147536 More information less... ABSTRACT: Key items discussed are the positivist synthesis methods meta-analysis and content analysis to address questions in the form of "whether and what" education is effective. These can be juxtaposed with the constructivist aligned thematic analysis and meta-ethnography to address questions in the form of "why." The concept of the realist review is also considered. It is proposed that authors of such work should describe their research alignment and the link between question, alignment and evidence synthesis method selected. Meeting the review family: Exploring review types and associated information retrieval requirements Sutton, A., Clowes, M., Preston, L., & Booth, A. (2019). Meeting the review family: Exploring review types and associated information retrieval requirements. Health Information & Libraries Journal, 36(3), 202–222. doi: 10.1111/hir.12276 Integrative Reviews "The integrative review method is an approach that allows for the inclusion of diverse methodologies (i.e. experimental and non-experimental research)." (Whittemore & Knafl, 2005, p. 547). The integrative review: Updated methodology Whittemore, R., & Knafl, K. (2005). The integrative review: Updated methodology. Journal of Advanced Nursing, 52 (5), 546–553. doi:10.1111/j.1365-2648.2005.03621.x More information less... ABSTRACT: The aim of this paper is to distinguish the integrative review method from other review methods and to propose methodological strategies specific to the integrative review method to enhance the rigour of the process....An integrative review is a specific review method that summarizes past empirical or theoretical literature to provide a more comprehensive understanding of a particular phenomenon or healthcare problem....Well-done integrative reviews present the state of the science, contribute to theory development, and have direct applicability to practice and policy. Conducting integrative reviews: A guide for novice nursing researchers Dhollande, S., Taylor, A., Meyer, S., & Scott, M. (2021). Conducting integrative reviews: A guide for novice nursing researchers. Journal of Research in Nursing, 26(5), 427–438. https://doi.org/10.1177/1744987121997907 Rigour in integrative reviews Whittemore, R. (2007). Rigour in integrative reviews. In C. Webb & B. Roe (Eds.), Reviewing Research Evidence for Nursing Practice (pp. 149–156). John Wiley & Sons, Ltd. https://doi.org/10.1002/9780470692127.ch11 Scoping Reviews Scoping reviews are evidence syntheses that are conducted systematically, but begin with a broader scope of question than traditional systematic reviews, allowing the research to 'map' the relevant literature on a given topic. Scoping studies: Towards a methodological framework Arksey, H., & O'Malley, L. (2005). Scoping studies: Towards a methodological framework. International Journal of Social Research Methodology, 8 (1), 19-32. doi:10.1080/1364557032000119616 More information less... ABSTRACT: We distinguish between different types of scoping studies and indicate where these stand in relation to full systematic reviews. We outline a framework for conducting a scoping study based on our recent experiences of reviewing the literature on services for carers for people with mental health problems. Scoping studies: Advancing the methodology Levac, D., Colquhoun, H., & O'Brien, K. K. (2010). Scoping studies: Advancing the methodology. Implementation Science, 5 (1), 69. doi:10.1186/1748-5908-5-69 More information less... ABSTRACT: We build upon our experiences conducting three scoping studies using the Arksey and O'Malley methodology to propose recommendations that clarify and enhance each stage of the framework. Methodology for JBI scoping reviews Peters, M. D. J., Godfrey, C. M., McInerney, P., Baldini Soares, C., Khalil, H., & Parker, D. (2015). The Joanna Briggs Institute reviewers’ manual: Methodology for JBI scoping reviews [PDF]. Retrieved from The Joanna Briggs Institute website: http://joannabriggs.org/assets/docs/sumari/Reviewers-Manual_Methodology-for-JBI-Scoping-Reviews_2015_v2.pdf More information less... ABSTRACT: Unlike other reviews that address relatively precise questions, such as a systematic review of the effectiveness of a particular intervention based on a precise set of outcomes, scoping reviews can be used to map the key concepts underpinning a research area as well as to clarify working definitions, and/or the conceptual boundaries of a topic. A scoping review may focus on one of these aims or all of them as a set. Systematic vs. Scoping Reviews: What's the Difference?  YouTube Video 4 minutes, 45 seconds Rapid Reviews Rapid reviews are systematic reviews that are undertaken under a tighter timeframe than traditional systematic reviews.  Evidence summaries: The evolution of a rapid review approach Khangura, S., Konnyu, K., Cushman, R., Grimshaw, J., & Moher, D. (2012). Evidence summaries: The evolution of a rapid review approach. Systematic Reviews, 1 (1), 10. doi:10.1186/2046-4053-1-10 More information less... ABSTRACT: Rapid reviews have emerged as a streamlined approach to synthesizing evidence - typically for informing emergent decisions faced by decision makers in health care settings. Although there is growing use of rapid review "methods," and proliferation of rapid review products, there is a dearth of published literature on rapid review methodology. This paper outlines our experience with rapidly producing, publishing and disseminating evidence summaries in the context of our Knowledge to Action (KTA) research program. What is a rapid review? A methodological exploration of rapid reviews in Health Technology Assessments Harker, J., & Kleijnen, J. (2012). What is a rapid review? A methodological exploration of rapid reviews in Health Technology Assessments. International Journal of Evidence‐Based Healthcare, 10 (4), 397-410. doi:10.1111/j.1744-1609.2012.00290.x More information less... ABSTRACT: In recent years, there has been an emergence of "rapid reviews" within Health Technology Assessments; however, there is no known published guidance or agreed methodology within recognised systematic review or Health Technology Assessment guidelines. In order to answer the research question "What is a rapid review and is methodology consistent in rapid reviews of Health Technology Assessments?", a study was undertaken in a sample of rapid review Health Technology Assessments from the Health Technology Assessment database within the Cochrane Library and other specialised Health Technology Assessment databases to investigate similarities and/or differences in rapid review methodology utilised. Rapid Review Guidebook Dobbins, M. (2017). Rapid review guidebook. Hamilton, ON: National Collaborating Centre for Methods and Tools. NCCMT Summary and Tool for Dobbins' Rapid Review Guidebook National Collaborating Centre for Methods and Tools. (2017). Rapid review guidebook. Hamilton, ON: McMaster University. Retrieved from http://www.nccmt.ca/knowledge-repositories/search/308 << Previous: Literature Reviews Next: Conducting & Reporting Systematic Reviews >> Last Updated: Jun 26, 2024 3:00 PM URL: https://guides.nyu.edu/speech 218 IMAGES Synthesis of the literature review process and main conclusion The synthesis of the literature review process. PPT Table 1 from A Synthesis of Literature Review Guidelines from How to Write a Literature Review Literature Review: Outline, Strategies, and Examples VIDEO Lecture Designing Organic Syntheses 4 Prof G Dyker 151014 Lecture Designing Organic Syntheses 7 Prof G Dyker 291014 Retrosynthetic Analysis Synthesis Matrix Literature Review in Research Top Synths from the early 2000's Critical Synthesis Literature Review 3 COMMENTS Synthesizing Sources There are two types of syntheses: explanatory syntheses and argumentative syntheses. Explanatory syntheses seek to bring sources together to explain a perspective and the reasoning behind it. Argumentative syntheses seek to bring sources together to make an argument. Both types of synthesis involve looking for relationships between sources and ... Synthesize A synthesis matrix helps you record the main points of each source and document how sources relate to each other. After summarizing and evaluating your sources, arrange them in a matrix or use a citation manager to help you see how they relate to each other and apply to each of your themes or variables. By arranging your sources by theme or ... Literature Synthesis 101: How To Guide + Examples This post is based on our popular online course, Literature Review Bootcamp. In the course, we walk you through the full process of developing a literature review, step by step. If it's your first time writing a literature review, you definitely want to use this link to get 50% off the course (limited-time offer). 6. Synthesize In the four examples below, only ONE shows a good example of synthesis: the fourth column, or Student D. For a web accessible version, click the link below the image. For a web accessible version, click the link below the image. How To Write Synthesis In Research: Example Steps Step 1 Organize your sources. Step 2 Outline your structure. Step 3 Write paragraphs with topic sentences. Step 4 Revise, edit and proofread. When you write a literature review or essay, you have to go beyond just summarizing the articles you've read - you need to synthesize the literature to show how it all fits together (and how your own ... What Synthesis Methodology Should I Use? A Review and Analysis of Types of Research Synthesis: Key Characteristics: Purpose: Methods: Product: CONVENTIONAL Integrative Review: What is it? "The integrative literature review is a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated" [, p.356]. ... LibGuides: Literature Review How To: Synthesizing Sources Literature reviews synthesize large amounts of information and present it in a coherent, organized fashion. In a literature review you will be combining material from several texts to create a new text - your literature review. You will use common points among the sources you have gathered to help you synthesize the material. Synthesizing Research Analyze what you learn in (4) using a tool like a Synthesis Table. Your goal is to identify relevant themes, trends, gaps, and issues in the research. Your literature review will collect the results of this analysis and explain them in relation to your research question. Analysis tips Chapter 7: Synthesizing Sources A literature review is not an annotated bibliography, organized by title, author, or date of publication. Rather, it is grouped by topic to create a whole view of the literature relevant to your research question. Figure 7.1. Your synthesis must demonstrate a critical analysis of the papers you collected as well as your ability to integrate the ... 5. The Literature Review A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories.A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that ... Types of Evidence Synthesis There are many types of evidence synthesis, and it is important to choose the right type of synthesis for your research questions. ... Literature Review: Generic term: published materials that provide examination of recent or current literature. Can cover wide range of subjects at various levels of completeness and comprehensiveness. Methodological Approaches to Literature Review This chapter discusses the methodological approaches to conducting a literature review and offers an overview of different types of reviews. There are various types of reviews, including narrative reviews, scoping reviews, and systematic reviews with reporting strategies such as meta-analysis and meta-synthesis. Synthesizing Sources Revised on May 31, 2023. Synthesizing sources involves combining the work of other scholars to provide new insights. It's a way of integrating sources that helps situate your work in relation to existing research. Synthesizing sources involves more than just summarizing. You must emphasize how each source contributes to current debates ... Guidance on Conducting a Systematic Literature Review The different literature review typologies discussed earlier and the type of literature being synthesized will guide the reviewer to appropriate synthesis methods. The synthesis methods, in turn, will guide the data extraction process—for example, if one is doing a meta-analysis, data extraction will be centered on what's needed for a meta ... Evidence Synthesis Review Types Scoping Review. A scoping review is a type of knowledge synthesis which follows a systematic approach to map evidence on a topic and identify main concepts, theories, sources, and knowledge gaps (Tricco, et. al, 2019). Scoping reviews can be a precursor to a systematic review and may take longer than a systematic review to complete. Use a scoping review to identify key concepts in the field ... Synthesise The synthesis part of a systematic review will determine the outcomes of the review. There are two commonly accepted methods of synthesis in systematic reviews: Quantitative data synthesis. Qualitative data synthesis. The way the data is extracted from your studies and synthesised and presented depends on the type of data being handled. Systematic Reviews & Evidence Synthesis Methods Evidence syntheses are much more time-intensive than traditional literature reviews and require a multi-person research team. See this PredicTER tool to get a sense of a systematic review timeline (one type of evidence synthesis). Before embarking on an evidence synthesis, it's important to clearly identify your reasons for conducting one. Types of Literature Review 1. Narrative Literature Review. A narrative literature review, also known as a traditional literature review, involves analyzing and summarizing existing literature without adhering to a structured methodology. It typically provides a descriptive overview of key concepts, theories, and relevant findings of the research topic. Types of Literature Review Systematic literature review can be divided into two categories: meta-analysis and meta-synthesis. When you conduct meta-analysis you take findings from several studies on the same subject and analyze these using standardized statistical procedures. In meta-analysis patterns and relationships are detected and conclusions are drawn. Different Types of Literature Reviews Most evidence synthesis methods use formal and explicit methods to identify, select and combine results from multiple studies, making evidence synthesis a form of meta-research. The review purpose, methods used and the results produced vary among different kinds of literature reviews; some of the common types of literature review are detailed ... Types of literature review, methods, & resources Meeting the review family: exploring review types and associated information retrieval requirements. Health information and libraries journal, 36(3), 202-222. doi:10.1111/hir.12276 (An updated look at different types of literature review, expands on the Grant & Booth 2009 article listed above). Garrard, J. (2007). Types of Reviews There are many types of reviews --- narrative reviews, scoping reviews, systematic reviews, integrative reviews, umbrella reviews, rapid reviews and others --- and it's not always straightforward to choose which type of review to conduct.These Review Navigator tools (see below) ask a series of questions to guide you through the various kinds of reviews and to help you determine the best choice ... Types of Reviews Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review. Systematic Review: Seeks to systematically search for, appraise and synthesis research evidence, often adhering to guidelines on the conduct of a review. Aims for exhaustive, comprehensive searching. Sustainability A systematic literature review was conducted on articles published between 2004 and 2024 from four databases: Scopus, ScienceDirect, Emerald Insights, and IEEE Xplore. ... learning and its settings. A total of 37 full-text articles were included in the descriptive review, from which two categories and six types were identified: private indoor ... ISPOR OBJECTIVES: Systematic literature reviews (SLRs) are a widely used research tool with established best practices. Non-systematic literature reviews (nSLRs) encompass a range of review types and implement varying approaches to searching, screening, and data extraction. We sought to collate established guidance for SLRs/nSLRs and to understand whether there was consistency in the language and ... Types of Literature Reviews Qualitative, narrative synthesis. Thematic analysis, may include conceptual models. Rapid review. Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research. Completeness of searching determined by time constraints. Pseudomyxoma peritonei leading to "jelly belly" abdomen: a case report Pseudomyxoma peritonei is an infrequent condition with a global annual incidence of only one to two cases per million people. Mucinous neoplasms, widespread intraperitoneal implants, and mucinous ascites characterize it. Currently, most clinicians misdiagnose this condition, which leads to delayed management. A 44-year-old North Indian female presented with a 1.5-month history of an abdominal ... JCM Heat shock proteins (HSPs) have been attracting the attention of researchers for many years. HSPs are a family of ubiquitous, well-characterised proteins that are generally regarded as protective multifunctional molecules that are expressed in response to different types of cell stress. Their activity in many organs has been reported, including the heart, brain, and retina. By acting as ... Overview of Review Types Scoping Review. A scoping review is a type of knowledge synthesis which follows a systematic approach to map evidence on a topic and identify main concepts, theories, sources, and knowledge gaps (Tricco, et. al, 2019). Scoping reviews can be a precursor to a systematic review and may take longer than a systematic review to complete. Use a scoping review to identify key concepts in the field ... What are Literature Reviews? Most evidence synthesis methods use formal and explicit methods to identify, select and combine results from multiple studies, making evidence synthesis a form of meta-research. The review purpose, methods used and the results produced vary among different kinds of literature reviews; some of the common types of literature review are detailed ... assignment essay homework paper phd report resume review speech thesis