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How to Synthesize Written Information from Multiple Sources

Shona McCombes

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B.A., English Literature, University of Glasgow

Shona McCombes is the content manager at Scribbr, Netherlands.

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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.

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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

Related Articles

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

A Guide to Evidence Synthesis: What is Evidence Synthesis?

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

What are Evidence Syntheses?

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 next tab.

How Does a Traditional Literature Review Differ From an Evidence Synthesis?

How does a systematic review differ from a traditional literature review.

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
• << Previous: Our Published Reviews and Protocols
• Next: Types of Evidence Synthesis >>
• Last Updated: May 6, 2024 12:12 PM
• URL: https://guides.library.cornell.edu/evidence-synthesis

Writing based on Texts

Drafting a research essay: synthesizing ideas.

Research can yield a lot of information and interesting ideas. You may find that you have so many ideas from your research, it’s hard to start writing a draft. If you did an  Idea Matrix to synthesize notes from many sources, then you have a good start at synthesizing ideas for an essay draft. Since an idea matrix focuses on organizing related ideas from a variety of sources, you now need to focus more on your own ideas in order to start a draft. In other words, you need to converse with your sources to achieve the kind of synthesis expected in a college research essay, which is intended to support and showcase your own ideas about an issue. In most college research essay assignments, your research should be used to support and supply evidence for your personal thoughts.

Here’s one way to proceed:

• First of all, if you have been working with a research question, now’s the time to answer that research question and create a working thesis, with a topic and an angle in which you make an assertion about your topic/issue.
• Then, review the supporting idea column of your idea matrix. Each idea listed offers in brief an idea group that can answer your research question and support your working thesis. Draft topic sentences, each with its own topic and angle, based on each supporting idea in your matrix.
• Finally and most importantly, add your own ideas to your idea matrix in a new column or by writing notes. What do you, yourself, think about these ideas? Do you agree or disagree with certain supporting information and why? Add samples from your own experience and additional thoughts to exemplify each supporting idea group in general, and each quotation, paraphrase, or summary in particular.

A good way to begin synthesizing your own with your sources’ ideas for an essay draft is to consider how you integrate ideas into a conversation. When you’re discussing a topic with a few friends, you might refer to others’ ideas with phrases such as these: “When I was watching the news, I heard them say that . . . ,” “I read in The Atlantic online that. . .,” “Jamal told me that . . . .”  It’s quite standard to use sentences such as these to refer to others’ ideas within the flow of conversation. It’s the same in drafting an essay. Ask yourself if you were speaking this aloud in conversation, how would you introduce others’ ideas to your listeners? What information would you give them to help them understand who the author was and why the views presented are worth referencing? After giving this information, how would you then link it back to the point you were trying to make? Just as you do this in a conversation when you refer to another’s ideas, you also need to do this in your writing.

Yet even though ideas need to blend in a conversation, the source of each idea needs to be totally clear. While you’re synthesizing your own thoughts with your research, you still need to clarify and differentiate between your own ideas and your sources’ ideas. Part of your job is to help your reader understand exactly which information and what ideas came from whom. When you’re drafting a research essay, then, synthesizing your ideas with your sources’ ideas is like making a minestrone vegetable soup—all of the flavorings blend together, even though you still see distinct pieces of tomato, zucchini, beans, pasta, and whatever else you’ve included. If you don’t identify the source of each idea, then you have a blended soup like carrot soup—you cannot differentiate the ingredients, so no one knows which idea belongs to whom.

Another food analogy may help you synthesize ideas in a research essay—a “source sandwich.” Whether you use a direct quotation, paraphrase, or summary, a source sandwich helps you distinguish source material from your own ideas and explain how that source material fits into your argument. A source sandwich includes a transition to introduce the source, an attribution to actually move into the material from the source, and an in-text citation that connects to the full citation material at the end. It also includes your own thoughts in the most important bottom piece of bread which holds all of the rest. The bottom of the sandwich synthesizes the source material by explaining how it fits into your argument, supports your topic sentence, and supports your working thesis. Use the source sandwich convention to synthesize material from sources into your own writing so that your source’s information complements your own ideas with supporting evidence.

The Source sandwich

Here’s a video that offers the concept of synthesizing your ideas with your research in yet another way.

Another Approach to Synthesizing Ideas: They Say/I Say

The page on Reading & Writing to Synthesize introduces the They Say/I Say concept of joining a conversation, a way to incorporate your original thinking with ideas from your sources. Sometimes you may cite a research finding that provides strong evidence for your point; at other times you may summarize someone else’s ideas in order to explain how your own opinion differs or to note how someone else’s concept applies to a new situation. In general, using this approach, you first report what “they” say, “they” being published authors, prevalent ideas in society at large, or maybe participants in some kind of political or social debate. Then you respond by explaining what you think: Do you agree? Disagree? A little of both?

The “They Say/I Say” approach can help you find balance in your use of sources. On one extreme, don’t assume that you aren’t allowed to make any claims without citing one or more expert authors saying the same thing. On the other extreme, don’t describe what sources say about a topic, but then go on to state opinions that seem unrelated to the claims just summarized. (For example, a student writer may draw on expert sources to explain how the prevention and early detection of cancer has saved lives, but then argue for more funding for curing advanced cancer without making any explicit link to the points about prevention and screening.) On one extreme, the sources are allowed to crowd out original thinking; on the other, they have seemingly no impact on the author’s conclusions.

How can you know when you’re avoiding both of these extremes? The concept of They Say/I Say can help you refine as well as support a working thesis. “I Say” can count as an original claim and still be grounded in the sources “They Say.” For example:

• Combine research findings from multiple sources to make a larger summary argument . You might find that none of the sources you’re working with specifically claim that early 20th century British literature was preoccupied with changing gender roles but that, together, their findings all point to that broader conclusion.
• Combine research findings from multiple sources to make a claim about their implications . You might review papers that explore various factors shaping voting behavior to argue that a particular voting-reform proposal will likely have positive impacts.
• Identify underlying areas of agreement . You may argue that the literature on cancer and the literature on violence both describe the unrecognized importance of prevention and early intervention in order to claim that insights about one set of problems may be useful for the other.
• Identify underlying areas of disagreement . You may find that the controversies surrounding educational reform—and its debates about accountability, curricula, school funding—ultimately stem from different assumptions about the role of schools in society.
• Identify unanswered questions . Perhaps you review studies of the genetic and behavioral contributors to diabetes in order to highlight unknown factors and argue for more in-depth research on the role of the environment.

These examples illustrate how original thinking in academic writing involves making connections with and between a strategically chosen set of sources.

Read the following paragraph about “mindful me” rooms in elementary schools and answer the questions that follow.

Reflective practice has also started to replace detention in schools across the country. Robert W. Coleman Elementary School is one of the first to adopt this method. As of 2014, this school has had no suspensions. When students fight or misbehave, they are sent to a “mindful me” room instead of the principal’s office, and they learn to peacefully solve these conflicts themselves (Khorsandi). Administrators at the school claim to have seen a marked improvement in student behavior. Coleman Principal Carillian Thompson explains, “The mindfulness practices have actually taught the students how to redirect that negative energy into something positive” (Khorsandi). The changes have resulted in more focus on academics and extracurricular activities at Coleman, which has made parents in the district happy. In fact, many parents have switched their thinking from once believing punitive measures are necessary to modify children’s behaviors to now seeing reflective practices as meaningful alternatives to detention.

• Which sentence contains a signal phrase?
• Coleman Principal Carillian Thompson explains, “The mindfulness practices have actually taught the students how to redirect that negative energy into something positive” (Khorsandi).
• Reflective practice has also started to replace detention in schools across the country.
• When students fight or misbehave, they are sent to a “mindful me” room instead of the principal’s office, and they learn to peacefully solve these conflicts themselves (Khorsandi).

Sentence #1 contains a signal phrase. Thompson’s name and credentials, plus the verb “explains,” constitute the signal phrase.

• In which sentence does the writer transition into using a source?
• The changes have resulted in more focus on academics and extracurricular activities at Coleman, which has made parents in the district happy.
• Coleman principal Carillian Thompson explains, “The mindfulness practices have actually taught the students how to redirect that negative energy into something positive” (Khorsandi).

Sentence #3 is correct, as the writer uses “also” to indicate a new point and example to come. Sentences #1 and #2 simply summarize points previously introduced.

• Which sentence explains the relevance of the source to the writer’s thesis?
• Robert W. Coleman Elementary School is one of the first to adopt this method.
• In fact, many parents have switched their thinking from once believing punitive measures are necessary to modify children’s behaviors to now seeing reflective practices as meaningful alternatives to detention.
• Administrators at the school claim to have seen a marked improvement in student behavior.

Sentence #2 is correct; the writer relates the source to her thesis. In sentences #1 and  #3, the writer describes/develops the evidence.

Synthesizing Ideas also involves Synthesizing Skills

Realize that as you synthesize ideas for a research paper, you’re also synthesizing reading and writing skills.

• Pre-writing – brainstorming, listing, mapping, etc. to create a research question and working thesis; reviewing your prewriting in the context of your writing’s purpose (e.g., to apply, analyze, etc.)
• Researching – finding appropriate types of sources and content to answer your research question and more firmly establish your working thesis
• Reading – skimming researched sources; evaluating them for content, relevance, etc.; reading fully for main ideas; annotating, note taking, or in some way recording and interacting with those ideas
• Paraphrasing and summarizing relevant ideas from your notes (relevant to your working thesis)
• Synthesizing ideas – finding relationships among ideas from different sources and synthesizing them in an idea matrix; evaluating the matrix for amount and type of support to see if more or different support is needed
• Drafting the research paper – intro-body-conclusion, determining the order of supporting ideas
• Reading the draft as a text in its own right to evaluate it (for purpose, content, clarity) and aid in revising and finalizing the paper
• Citing sources
• Drafting a Research Essay: Synthesizing Ideas, includes material adpated from Basic Reading and Writing, UMiss RhetLab, and Writing in College: From Competence to Excellence; attributions below. Authored by : Susan Oaks. Project : Introduction to College Reading & Writing. License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
• Finding Evidence. Provided by : Lumen Learning. Located at : https://courses.lumenlearning.com/suny-basicreadingwriting/chapter/outcome-finding-evidence/ . Project : Basic Reading and Writing. License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
• Bringing Sources into the Conversation. Provided by : Lumen Learning. Located at : https://courses.lumenlearning.com/olemiss-writing100/chapter/bringing-sources-into-the-conversation/ . Project : UM RhetLab. License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
• Listening to Sources, Talking to Sources. Authored by : Amy Guptill. Provided by : The College at Brockport, SUNY. Located at : https://milnepublishing.geneseo.edu/writing-in-college-from-competence-to-excellence/chapter/listening-to-sources-talking-to-sources/ . Project : Writing in College: From Competence to Excellence. License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
• image of woman holding laptop in front of jigsaw puzzle pieces. Authored by : Gerd Altmann. Provided by : Pixabay. Located at : https://pixabay.com/photos/businesswoman-business-puzzle-2822600/ . License : CC0: No Rights Reserved
• video How to Plan and Write a Paper: How to Draft. Authored by : Clancy Clawson. Provided by : University of Maryland, Baltimore Writing Center. Located at : https://www.youtube.com/watch?v=myHkqdkhBYg . License : Other . License Terms : YouTube video
• image of minestrone soup in a bowl. Authored by : catceeq. Provided by : Pixabay. Located at : https://pixabay.com/photos/soup-minestrone-soup-vegetable-soup-4769456/ . License : CC0: No Rights Reserved
• image of carrot soup in a bowl. Authored by : Christo Anestev. Provided by : Pixabay. Located at : https://pixabay.com/photos/carrots-soup-fresh-soup-food-soup-2157198/ . License : CC0: No Rights Reserved
• video How to Write a Body Paragraph for a Research Paper. Authored by : Tyler Rablin. Located at : https://www.youtube.com/watch?v=WJDsV05fIXk . License : Other . License Terms : YouTube video

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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.

Literature Review How To

• Things To Consider
• 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. 
• << Previous: Things To Consider
• Next: Video Tutorials >>
• Last Updated: Nov 30, 2018 4:51 PM
• URL: https://libguides.csun.edu/literature-review

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UMGC Effective Writing Center Write to Synthesize: The Research Essay

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In a synthesis, you bring things together. This combination, integration, or merging creates something new--your synthesis. The action of synthesis is basic to our world. Take, for example, what happens when a single oxygen molecule is combined with two hydrogen molecules. Water is created or synthesized. Hard to get more basic than that.

You also use synthesis to make personal decisions. If two instructors are teaching a class you must take, you may synthesize your past experiences with the teachers to choose the best class for you.

Research Essays:

Thesis driven.

In school, when writing a synthesis from your research, your sources may come from the school's library, a textbook, or the Internet. Here are some important points to keep in mind:

First, regardless of where your sources come from or how many you have, what you write should be driven by a thesis that you devise. After reading and studying your sources, you should form a personal point of view, a slant to connect your sources.

Here's a quick example--Let's say you've read three folktales: Goldilocks and the Three Bears, Little Red Riding Hood, and the Pied Piper--and now you must write a synthesis of them. As you study the three sources, you think about links between them and come up with this thesis: 

Folktales use fear to teach children lessons.

Then you use this thesis to synthesize your three sources as you support your point of view. You combine elements from the three sources to prove and illustrate this thesis. Your support points could focus on the lessons for children:

• Lesson 1 : Never talk to strangers.
• Lesson 2 : Don't wander from home.
• Lesson 3 : Appearances can deceive us.

This step of outlining your thesis and main points is a crucial one when writing a synthesis. If your goal in writing a research essay is to provide readers a unified perspective based on sources, the unified perspective must be clear before the writing begins.

Once the writing begins, your point of view is then carried through to the paragraph and sentence levels. Let's examine some techniques for achieving the unity that a good synthesis requires. First, here’s an example of an unsuccessful attempt at synthesizing sources:

Many sources agree that capital punishment is not a crime deterrent. [This is the idea around which the sources should be unified. Now comes the sources] According to Judy Pennington in an interview with Helen Prejean, crime rates in New Orleans rise for at least eight weeks following executions (110). Jimmy Dunne notes that crime rates often go up in the first two or three months following an execution. “Death in the Americas” argues that America’s crime rate as a whole has increased drastically since the re-instatement of the death penalty in the 1960s. The article notes that 700 crimes are committed for every 100,000 Americans (2). Helen Prejean cites Ellis in her book to note that in 1980, 500,000 people were behind bars and in 1990 that figure rose to 1.1 million (112).

Sample student paragraph adapted from "Literature Review: Synthesizing Multiple Sources." Retrieved 2011 from https://scholarworks.iupui.edu/items/7dda80e7-b0b3-477c-a972-283b48cfdf5c

This paragraph certainly uses a number of sources. However, the sources are presented in a random, grocery list fashion. Besides the main point at the beginning, there is no further attempt to synthesize. The sources seem tossed in, like ingredients in a salad. Let's examine a possible revision of that paragraph and how an adequate synthesis might be achieved:

Major studies suggest that capital punishment fails to deter crime. Helen Prejean, in "Deadman Walking," reviews decades of statistics that indicate capital punishment does little to lower crime. [Key idea from  topic sentence—"capital punishment fails to deter crime"— echoed in sentence about source–"capital punishment does little to lower crime." Repetition links source to main idea.] Based on this evidence, Prejean concludes “Executions do not deter crime . . . the U.S. murder rate is no higher in states that do not have the death penalty than those who do” (110). ["Based on this evidence" forces  reader to refer back to "statistics" in previous sentence.] Prejean’s point is reiterated from a historical perspective in Dunne's article “Death in the Americas.”  [This sentence provides a thought bridge between two sources.] Dunne first points out that, despite the social and economic upheavals from 1930 to 1960, crime rates were unchanged (2). [Linking phrase:"Dunne first points out"] However, after the reinstatement of the death penalty in the 1960s, “crime rates soared” (2). [Linking phase "However, Dunne notes."]

The result is a matrix of connective devices that unifies the sources around a key idea stated at the beginning. Although this matrix seems complex, it is actually built on a simple three-point strategy.

• Stay in charge . You the writer must control the sources, using them to serve your purpose. In good synthesis writing, sources are used to support what you, the writer, have already said in your own words.
• Stay focused . Your main point is not merely stated once and left to wilt. Your main idea is repeated and echoed throughout as a way to link the sources, to weave them together into a strong fabric of meaning.
• Stay strategic . Notice the "source sandwich" strategy at work. First, the author sets up the source with its background and relevance to the point. After the source comes a follows up in his/her own words as a way to bridge or link to the next part. In other words, the writer's own words are used like two slices of bread, with the source in the middle.

Follow these simple principles when using sources in your writing and you will achieve the most important goal of synthesis writing--to create a whole greater than its parts.

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• v.3(1); 2016

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.

Research Guides

Information Literacy & Library Research: Information Synthesis

• Table of Contents
• Information Literacy
• Research Process
• Topics and Background Research
• Writing a Research Question
• Source Types
• Keyword Basics
• Research: A Journey in Small Steps
• Keywords and Boolean Logic
• Using Databases
• How to Find Books and eBooks
• Popular vs Scholarly
• "Search the Library" through the EBSCO Discovery Service
• Applying the CRAAP Test to Sources
• Citing with MLA 9
• Information Synthesis
• How to Critically Read Academic Articles
• Information Has Value
• How to Avoid Plagiarism
• Module 6. Reflecting
• Academic Honesty and Plagiarism
• Copyright and Fair Use
• Creative Commons Licenses
• Information has Value
• Joining the Scholarly Conversation
• Library Classification Systems
• Google Scholar
• Subject Databases
• Find Journal by Title
• Advanced Search Strategies
• MLA Style Examples
• APA Style Examples

Introduction: Scholarship is a Conversation

Information synthesis is the process of analyzing and evaluating information from various sources, making connections between the information found, and combining the recently acquired information with prior knowledge to create something new. Without information synthesis strategies, we cannot derive new knowledge from these large amounts of data. Effective information synthesis is also vital in developing effective writing and communication skills to share new knowledge.

Here is an example of a paragraph where the authors have synthesized information across several sources on the idea of information synthesis. Note also how connector words are used to make the writing flow.

Information synthesis is a key skill for participants in our knowledge society and requires complex processing (Fitzgerald, 2004; Goldman, 2004). Yet information literacy instruction and practice tend to favor easily-defined skills that often only emphasize the search component of the research process, leaving out higher order processes like information synthesis (Lloyd, 2007; Montiel-Overall, 2007). Similarly, in the writing classroom, teachers are largely unfamiliar with how to teach synthesis sometimes implying it is a linear process (McGinley, 1992), leading Mateos and Sole (2009) to call for a “unique, careful teaching approach” (p. 448).

Creating the Information Synthesis Matrix

Important questions to answer when you are reading your sources are: What are the major themes or ideas? How are these ideas related to each other? What are my assertions based on what I’ve learned about these ideas and my prior knowledge on this topic?

Keeping track of ideas gets more complex the more sources you are using. This is where the information synthesis matrix comes in. It is a table where the first column collects the ideas, and all the other columns are taken up by your sources, one source per column. Each row represents a unique idea. In the intersection of sources and ideas, the cells of the matrix, you provide short descriptions of how this idea is represented in that source (adding the page number at the end of the description can also remind you where you got the idea).You leave the cell blank if that idea does not appear in a source. If you find an existing idea that already has a row, find the cell where your new source and that idea intersect, and put the description there. Make sure that your descriptions are in your own words so they can easily be used when writing a synthesized paragraph for your paper and are not plagiarized. 

This is an abbreviated matrix but you can view more complete synthesis matrix examples to help you understand how to create your own.

Note for INFO 1010:

For the Synthesize: Module 5 Assignment you create a synthesis matrix using the sources you found for your paper. The synthesis matrix is a good way to keep track of the ideas you read about in your sources which will be very helpful when you create an outline for your paper and write a first draft. 

Shortened video (9:47):

Full Length Video (21:44):

Paraphrasing, Summarizing, and Quoting

When creating your synthesis matrix, it is best for you to keep the information in each cell shorter, so the size of the matrix stays manageable. This can be done by summarizing or paraphrasing how your sources talk about each main idea. Summarizing and paraphrasing are also good ways to make sure you use your own voice more, which is an important part of synthesis. An added benefit of using your own voice is that you are avoiding plagiarism . Please keep quotes to a minimum as professors are interested in reading your original thoughts and interpretations. 

Paraphrasing is when you use different words to say the same thing without actually quoting the source. It involves fully understanding the original source and then using your own words to convey the same idea. Make sure to add the page number of the source (if possible) in the cell with your paraphrase.

Summarizing is when you give an overview of the text. It will always reduce the content to the important points without using details or examples. Summarizing is ideal for your synthesis matrix because you will be able to get the idea of how that source talks about the main point without taking a lot of space. Including the page number from the original source will help you know where to return for those details when you start to write your paper.

Quoting is when you take the exact wording used by your source and use it in your paper. Quoting is good for providing strong evidence to support your point. However, use quotes sparingly or not at all. Good things to quote are definitions or text that is written so beautifully you want to frame it to hang on your wall. When deciding to use a quote in your matrix, put it in quotation marks and include the page number. This way you will know it is a quote and not accidentally plagiarize later, and quotes require an in-text citation with a page number. If the quote is too long for the cell, include part of the quote and add [...] to show there is more and then end with the page number (p. #).

Writing Using the Information Synthesis Matrix

Once you have read enough sources and you have added them to your synthesis matrix, it is time to use the matrix to write your paper. Because you have collected all the interesting ideas in your matrix (in first column, one idea per row), you can now use that first column to create an outline for your paper by determining a logical order in which to discuss the ideas. Next, you can use each row to write a paragraph or section on that idea, integrating information from all the sources that had something on that idea. Finally, you can also easily see when you don’t have enough sources for an idea. In some cases, the idea might not be that important for your paper. Other times the idea is something that you want to include in your paper so you go out and find more sources, specifically on that idea.

When you write a paragraph in which you synthesize ideas, you can use so-called transition words that: 1) add to an idea (e.g. furthermore, moreover, in addition); 2) introduce information (e.g. for example, for instance, including, as an illustration); 3) compare and contrast (e.g. similarly, in the same way, conversely, however); 4) make a concession (e.g. nevertheless, even though, despite this). See http://www.csuci.edu/cis/CIS_Science_Writing_Pilot/helpful-steps.pdf for more information.

A more detailed description on creating and using an information synthesis matrix in the writing process, was created by Utah State University:  https://libguides.usu.edu/synthesizing_info

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Synthesis of Your Own Ideas

Professors want to see evidence of your own thinking in your essays and papers. Even so, it will be your thoughts in reaction to your sources:

• What was the author really trying to say?
• What parts of them do you agree with?
• What parts of them do you disagree with?
• Did they leave anything out?
• What does an author’s work lead you to say?

It’s wise to not only analyze—take apart for study—the sources, but also to try to combine your own ideas with those presented in class and in the resources. Professors frequently expect you to interpret, make inferences, and otherwise synthesize—bring ideas together to make something new or find a new way of looking at something old. It might help to think of synthesis as the opposite of analysis.

Getting Better at Synthesis

To get an A on essays and papers in many courses, such as literature and history, when you write in reaction to others’ work you should use synthesis to create new meaning or show a deeper understanding of what you learned. To do so, it helps to look for connections and patterns. One way to synthesize when writing an argument essay, paper, or other project is to look for themes among your sources. So try categorizing ideas by topic rather than by resource—making associations across sources. Synthesis can seem difficult, particularly if you are used to analyzing others’ points but are not used to making your own. Like most things, however, it gets easier as you get more experienced at it. So don’t be hard on yourself if it seems difficult at first.

Example: Synthesis in an Argument

Imagine that you have to write an argument essay about Woody Allen’s 2011 movie Midnight in Paris . Your topic is “nostalgia,” and the movie is the only resource you can use. In the movie, a successful young screenwriter named Gil is visiting Paris with his girlfriend and her parents, who are more politically conservative than he is. Inexplicably, every midnight he time-travels back to the 1920’s Paris, a time period he’s always found fascinating, especially because of the writers and painters—Hemingway, Fitzgerald, Picasso—that he’s now on a first-name basis with. Gil is enchanted and always wants to stay. But every morning, he’s back in real-time—feeling out of sync with his girlfriend and her parents.

You’ve tried to come up with a narrower topic, but so far nothing seems right. Suddenly, you start paying more attention to the girlfriend’s parents’ dialogue about politics, which amount to such phrases as “we have to go back to…,” “it was a better time,” “Americans used to be able to…” and “the way it used to be.” And then it clicks with you that the girlfriend’s parents are like Gil—longing for a different time, whether real or imagined. That kind of idea generation is synthesis.

You decide to write your essay to answer the research question: How is the motivation of Gil’s girlfriend’s parents similar to Gil’s? Your thesis becomes “Despite seeming to be not very much alike, Gil and the parents are similarly motivated, and Woody Allen meant Midnight in Paris ‘s message about nostalgia to be applied to all of them.” Of course, you’ll have to try to convince your readers that your thesis is valid and you may or not be successful—but that’s true with all theses. And your professor will be glad to see the synthesis.

There is a lot more you can learn about creating synthesis in scholarly writing. One place synthesis is usually required is in literature reviews for honors’ theses, master’s theses, and Ph.D. dissertations. In all those cases, literature reviews are intended to contribute more than annotated bibliographies do and to be arguments for the research conducted for the theses or dissertations. If you are writing an honors thesis, master’s thesis, or Ph.D. dissertation, check out Susan Imel’s Writing a Literature Review for more advice.

Critical Thinking in Academic Research Copyright © 2022 by Cindy Gruwell and Robin Ewing is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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