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References in Research – Types, Examples and Writing Guide

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References in Research

Definition:

References in research are a list of sources that a researcher has consulted or cited while conducting their study. They are an essential component of any academic work, including research papers, theses, dissertations, and other scholarly publications.

Types of References

There are several types of references used in research, and the type of reference depends on the source of information being cited. The most common types of references include:

References to books typically include the author’s name, title of the book, publisher, publication date, and place of publication.

Example: Smith, J. (2018). The Art of Writing. Penguin Books.

Journal Articles

References to journal articles usually include the author’s name, title of the article, name of the journal, volume and issue number, page numbers, and publication date.

Example: Johnson, T. (2021). The Impact of Social Media on Mental Health. Journal of Psychology, 32(4), 87-94.

Web sources

References to web sources should include the author or organization responsible for the content, the title of the page, the URL, and the date accessed.

Example: World Health Organization. (2020). Coronavirus disease (COVID-19) advice for the public. Retrieved from https://www.who.int/emergencies/disease/novel-coronavirus-2019/advice-for-public

Conference Proceedings

References to conference proceedings should include the author’s name, title of the paper, name of the conference, location of the conference, date of the conference, and page numbers.

Example: Chen, S., & Li, J. (2019). The Future of AI in Education. Proceedings of the International Conference on Educational Technology, Beijing, China, July 15-17, pp. 67-78.

References to reports typically include the author or organization responsible for the report, title of the report, publication date, and publisher.

Example: United Nations. (2020). The Sustainable Development Goals Report. United Nations.

Formats of References

Some common Formates of References with their examples are as follows:

APA (American Psychological Association) Style

The APA (American Psychological Association) Style has specific guidelines for formatting references used in academic papers, articles, and books. Here are the different reference formats in APA style with examples:

Author, A. A. (Year of publication). Title of book. Publisher.

Example : Smith, J. K. (2005). The psychology of social interaction. Wiley-Blackwell.

Journal Article

Author, A. A., Author, B. B., & Author, C. C. (Year of publication). Title of article. Title of Journal, volume number(issue number), page numbers.

Example : Brown, L. M., Keating, J. G., & Jones, S. M. (2012). The role of social support in coping with stress among African American adolescents. Journal of Research on Adolescence, 22(1), 218-233.

Author, A. A. (Year of publication or last update). Title of page. Website name. URL.

Example : Centers for Disease Control and Prevention. (2020, December 11). COVID-19: How to protect yourself and others. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html

Magazine article

Author, A. A. (Year, Month Day of publication). Title of article. Title of Magazine, volume number(issue number), page numbers.

Example : Smith, M. (2019, March 11). The power of positive thinking. Psychology Today, 52(3), 60-65.

Newspaper article:

Author, A. A. (Year, Month Day of publication). Title of article. Title of Newspaper, page numbers.

Example: Johnson, B. (2021, February 15). New study shows benefits of exercise on mental health. The New York Times, A8.

Edited book

Editor, E. E. (Ed.). (Year of publication). Title of book. Publisher.

Example : Thompson, J. P. (Ed.). (2014). Social work in the 21st century. Sage Publications.

Chapter in an edited book:

Author, A. A. (Year of publication). Title of chapter. In E. E. Editor (Ed.), Title of book (pp. page numbers). Publisher.

Example : Johnson, K. S. (2018). The future of social work: Challenges and opportunities. In J. P. Thompson (Ed.), Social work in the 21st century (pp. 105-118). Sage Publications.

MLA (Modern Language Association) Style

The MLA (Modern Language Association) Style is a widely used style for writing academic papers and essays in the humanities. Here are the different reference formats in MLA style:

Author’s Last name, First name. Title of Book. Publisher, Publication year.

Example : Smith, John. The Psychology of Social Interaction. Wiley-Blackwell, 2005.

Journal article

Author’s Last name, First name. “Title of Article.” Title of Journal, volume number, issue number, Publication year, page numbers.

Example : Brown, Laura M., et al. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence, vol. 22, no. 1, 2012, pp. 218-233.

Author’s Last name, First name. “Title of Webpage.” Website Name, Publication date, URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC, 11 Dec. 2020, https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Publication date, page numbers.

Example : Smith, Mary. “The Power of Positive Thinking.” Psychology Today, Mar. 2019, pp. 60-65.

Newspaper article

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Publication date, page numbers.

Example : Johnson, Bob. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, 15 Feb. 2021, p. A8.

Editor’s Last name, First name, editor. Title of Book. Publisher, Publication year.

Example : Thompson, John P., editor. Social Work in the 21st Century. Sage Publications, 2014.

Chapter in an edited book

Author’s Last name, First name. “Title of Chapter.” Title of Book, edited by Editor’s First Name Last name, Publisher, Publication year, page numbers.

Example : Johnson, Karen S. “The Future of Social Work: Challenges and Opportunities.” Social Work in the 21st Century, edited by John P. Thompson, Sage Publications, 2014, pp. 105-118.

Chicago Manual of Style

The Chicago Manual of Style is a widely used style for writing academic papers, dissertations, and books in the humanities and social sciences. Here are the different reference formats in Chicago style:

Example : Smith, John K. The Psychology of Social Interaction. Wiley-Blackwell, 2005.

Author’s Last name, First name. “Title of Article.” Title of Journal volume number, no. issue number (Publication year): page numbers.

Example : Brown, Laura M., John G. Keating, and Sarah M. Jones. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence 22, no. 1 (2012): 218-233.

Author’s Last name, First name. “Title of Webpage.” Website Name. Publication date. URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC. December 11, 2020. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Publication date.

Example : Smith, Mary. “The Power of Positive Thinking.” Psychology Today, March 2019.

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Publication date.

Example : Johnson, Bob. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Example : Thompson, John P., ed. Social Work in the 21st Century. Sage Publications, 2014.

Author’s Last name, First name. “Title of Chapter.” In Title of Book, edited by Editor’s First Name Last Name, page numbers. Publisher, Publication year.

Example : Johnson, Karen S. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by John P. Thompson, 105-118. Sage Publications, 2014.

Harvard Style

The Harvard Style, also known as the Author-Date System, is a widely used style for writing academic papers and essays in the social sciences. Here are the different reference formats in Harvard Style:

Author’s Last name, First name. Year of publication. Title of Book. Place of publication: Publisher.

Example : Smith, John. 2005. The Psychology of Social Interaction. Oxford: Wiley-Blackwell.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Journal volume number (issue number): page numbers.

Example: Brown, Laura M., John G. Keating, and Sarah M. Jones. 2012. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence 22 (1): 218-233.

Author’s Last name, First name. Year of publication. “Title of Webpage.” Website Name. URL. Accessed date.

Example : Centers for Disease Control and Prevention. 2020. “COVID-19: How to Protect Yourself and Others.” CDC. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html. Accessed April 1, 2023.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Magazine, month and date of publication.

Example : Smith, Mary. 2019. “The Power of Positive Thinking.” Psychology Today, March 2019.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Newspaper, month and date of publication.

Example : Johnson, Bob. 2021. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Editor’s Last name, First name, ed. Year of publication. Title of Book. Place of publication: Publisher.

Example : Thompson, John P., ed. 2014. Social Work in the 21st Century. Thousand Oaks, CA: Sage Publications.

Author’s Last name, First name. Year of publication. “Title of Chapter.” In Title of Book, edited by Editor’s First Name Last Name, page numbers. Place of publication: Publisher.

Example : Johnson, Karen S. 2014. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by John P. Thompson, 105-118. Thousand Oaks, CA: Sage Publications.

Vancouver Style

The Vancouver Style, also known as the Uniform Requirements for Manuscripts Submitted to Biomedical Journals, is a widely used style for writing academic papers in the biomedical sciences. Here are the different reference formats in Vancouver Style:

Author’s Last name, First name. Title of Book. Edition number. Place of publication: Publisher; Year of publication.

Example : Smith, John K. The Psychology of Social Interaction. 2nd ed. Oxford: Wiley-Blackwell; 2005.

Author’s Last name, First name. Title of Article. Abbreviated Journal Title. Year of publication; volume number(issue number):page numbers.

Example : Brown LM, Keating JG, Jones SM. The Role of Social Support in Coping with Stress among African American Adolescents. J Res Adolesc. 2012;22(1):218-233.

Author’s Last name, First name. Title of Webpage. Website Name [Internet]. Publication date. [cited date]. Available from: URL.

Example : Centers for Disease Control and Prevention. COVID-19: How to Protect Yourself and Others [Internet]. 2020 Dec 11. [cited 2023 Apr 1]. Available from: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. Title of Article. Title of Magazine. Year of publication; month and day of publication:page numbers.

Example : Smith M. The Power of Positive Thinking. Psychology Today. 2019 Mar 1:32-35.

Author’s Last name, First name. Title of Article. Title of Newspaper. Year of publication; month and day of publication:page numbers.

Example : Johnson B. New Study Shows Benefits of Exercise on Mental Health. The New York Times. 2021 Feb 15:A4.

Editor’s Last name, First name, editor. Title of Book. Edition number. Place of publication: Publisher; Year of publication.

Example: Thompson JP, editor. Social Work in the 21st Century. 1st ed. Thousand Oaks, CA: Sage Publications; 2014.

Author’s Last name, First name. Title of Chapter. In: Editor’s Last name, First name, editor. Title of Book. Edition number. Place of publication: Publisher; Year of publication. page numbers.

Example : Johnson KS. The Future of Social Work: Challenges and Opportunities. In: Thompson JP, editor. Social Work in the 21st Century. 1st ed. Thousand Oaks, CA: Sage Publications; 2014. p. 105-118.

Turabian Style

Turabian style is a variation of the Chicago style used in academic writing, particularly in the fields of history and humanities. Here are the different reference formats in Turabian style:

Author’s Last name, First name. Title of Book. Place of publication: Publisher, Year of publication.

Example : Smith, John K. The Psychology of Social Interaction. Oxford: Wiley-Blackwell, 2005.

Author’s Last name, First name. “Title of Article.” Title of Journal volume number, no. issue number (Year of publication): page numbers.

Example : Brown, LM, Keating, JG, Jones, SM. “The Role of Social Support in Coping with Stress among African American Adolescents.” J Res Adolesc 22, no. 1 (2012): 218-233.

Author’s Last name, First name. “Title of Webpage.” Name of Website. Publication date. Accessed date. URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC. December 11, 2020. Accessed April 1, 2023. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Month Day, Year of publication, page numbers.

Example : Smith, M. “The Power of Positive Thinking.” Psychology Today, March 1, 2019, 32-35.

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Month Day, Year of publication.

Example : Johnson, B. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Editor’s Last name, First name, ed. Title of Book. Place of publication: Publisher, Year of publication.

Example : Thompson, JP, ed. Social Work in the 21st Century. Thousand Oaks, CA: Sage Publications, 2014.

Author’s Last name, First name. “Title of Chapter.” In Title of Book, edited by Editor’s Last name, First name, page numbers. Place of publication: Publisher, Year of publication.

Example : Johnson, KS. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by Thompson, JP, 105-118. Thousand Oaks, CA: Sage Publications, 2014.

IEEE (Institute of Electrical and Electronics Engineers) Style

IEEE (Institute of Electrical and Electronics Engineers) style is commonly used in engineering, computer science, and other technical fields. Here are the different reference formats in IEEE style:

Author’s Last name, First name. Book Title. Place of Publication: Publisher, Year of publication.

Example : Oppenheim, A. V., & Schafer, R. W. Discrete-Time Signal Processing. Upper Saddle River, NJ: Prentice Hall, 2010.

Author’s Last name, First name. “Title of Article.” Abbreviated Journal Title, vol. number, no. issue number, pp. page numbers, Month year of publication.

Example: Shannon, C. E. “A Mathematical Theory of Communication.” Bell System Technical Journal, vol. 27, no. 3, pp. 379-423, July 1948.

Conference paper

Author’s Last name, First name. “Title of Paper.” In Title of Conference Proceedings, Place of Conference, Date of Conference, pp. page numbers, Year of publication.

Example: Gupta, S., & Kumar, P. “An Improved System of Linear Discriminant Analysis for Face Recognition.” In Proceedings of the 2011 International Conference on Computer Science and Network Technology, Harbin, China, Dec. 2011, pp. 144-147.

Author’s Last name, First name. “Title of Webpage.” Name of Website. Date of publication or last update. Accessed date. URL.

Example : National Aeronautics and Space Administration. “Apollo 11.” NASA. July 20, 1969. Accessed April 1, 2023. https://www.nasa.gov/mission_pages/apollo/apollo11.html.

Technical report

Author’s Last name, First name. “Title of Report.” Name of Institution or Organization, Report number, Year of publication.

Example : Smith, J. R. “Development of a New Solar Panel Technology.” National Renewable Energy Laboratory, NREL/TP-6A20-51645, 2011.

Author’s Last name, First name. “Title of Patent.” Patent number, Issue date.

Example : Suzuki, H. “Method of Producing Carbon Nanotubes.” US Patent 7,151,019, December 19, 2006.

Standard Title. Standard number, Publication date.

Example : IEEE Standard for Floating-Point Arithmetic. IEEE Std 754-2008, August 29, 2008

ACS (American Chemical Society) Style

ACS (American Chemical Society) style is commonly used in chemistry and related fields. Here are the different reference formats in ACS style:

Author’s Last name, First name; Author’s Last name, First name. Title of Article. Abbreviated Journal Title Year, Volume, Page Numbers.

Example : Wang, Y.; Zhao, X.; Cui, Y.; Ma, Y. Facile Preparation of Fe3O4/graphene Composites Using a Hydrothermal Method for High-Performance Lithium Ion Batteries. ACS Appl. Mater. Interfaces 2012, 4, 2715-2721.

Author’s Last name, First name. Book Title; Publisher: Place of Publication, Year of Publication.

Example : Carey, F. A. Organic Chemistry; McGraw-Hill: New York, 2008.

Author’s Last name, First name. Chapter Title. In Book Title; Editor’s Last name, First name, Ed.; Publisher: Place of Publication, Year of Publication; Volume number, Chapter number, Page Numbers.

Example : Grossman, R. B. Analytical Chemistry of Aerosols. In Aerosol Measurement: Principles, Techniques, and Applications; Baron, P. A.; Willeke, K., Eds.; Wiley-Interscience: New York, 2001; Chapter 10, pp 395-424.

Author’s Last name, First name. Title of Webpage. Website Name, URL (accessed date).

Example : National Institute of Standards and Technology. Atomic Spectra Database. https://www.nist.gov/pml/atomic-spectra-database (accessed April 1, 2023).

Author’s Last name, First name. Patent Number. Patent Date.

Example : Liu, Y.; Huang, H.; Chen, H.; Zhang, W. US Patent 9,999,999, December 31, 2022.

Author’s Last name, First name; Author’s Last name, First name. Title of Article. In Title of Conference Proceedings, Publisher: Place of Publication, Year of Publication; Volume Number, Page Numbers.

Example : Jia, H.; Xu, S.; Wu, Y.; Wu, Z.; Tang, Y.; Huang, X. Fast Adsorption of Organic Pollutants by Graphene Oxide. In Proceedings of the 15th International Conference on Environmental Science and Technology, American Chemical Society: Washington, DC, 2017; Volume 1, pp 223-228.

AMA (American Medical Association) Style

AMA (American Medical Association) style is commonly used in medical and scientific fields. Here are the different reference formats in AMA style:

Author’s Last name, First name. Article Title. Journal Abbreviation. Year; Volume(Issue):Page Numbers.

Example : Jones, R. A.; Smith, B. C. The Role of Vitamin D in Maintaining Bone Health. JAMA. 2019;321(17):1765-1773.

Author’s Last name, First name. Book Title. Edition number. Place of Publication: Publisher; Year.

Example : Guyton, A. C.; Hall, J. E. Textbook of Medical Physiology. 13th ed. Philadelphia, PA: Saunders; 2015.

Author’s Last name, First name. Chapter Title. In: Editor’s Last name, First name, ed. Book Title. Edition number. Place of Publication: Publisher; Year: Page Numbers.

Example: Rajakumar, K. Vitamin D and Bone Health. In: Holick, M. F., ed. Vitamin D: Physiology, Molecular Biology, and Clinical Applications. 2nd ed. New York, NY: Springer; 2010:211-222.

Author’s Last name, First name. Webpage Title. Website Name. URL. Published date. Updated date. Accessed date.

Example : National Cancer Institute. Breast Cancer Prevention (PDQ®)–Patient Version. National Cancer Institute. https://www.cancer.gov/types/breast/patient/breast-prevention-pdq. Published October 11, 2022. Accessed April 1, 2023.

Author’s Last name, First name. Conference presentation title. In: Conference Title; Conference Date; Place of Conference.

Example : Smith, J. R. Vitamin D and Bone Health: A Meta-Analysis. In: Proceedings of the Annual Meeting of the American Society for Bone and Mineral Research; September 20-23, 2022; San Diego, CA.

Thesis or dissertation

Author’s Last name, First name. Title of Thesis or Dissertation. Degree level [Doctoral dissertation or Master’s thesis]. University Name; Year.

Example : Wilson, S. A. The Effects of Vitamin D Supplementation on Bone Health in Postmenopausal Women [Doctoral dissertation]. University of California, Los Angeles; 2018.

ASCE (American Society of Civil Engineers) Style

The ASCE (American Society of Civil Engineers) style is commonly used in civil engineering fields. Here are the different reference formats in ASCE style:

Author’s Last name, First name. “Article Title.” Journal Title, volume number, issue number (year): page numbers. DOI or URL (if available).

Example : Smith, J. R. “Evaluation of the Effectiveness of Sustainable Drainage Systems in Urban Areas.” Journal of Environmental Engineering, vol. 146, no. 3 (2020): 04020010. https://doi.org/10.1061/(ASCE)EE.1943-7870.0001668.

Example : McCuen, R. H. Hydrologic Analysis and Design. 4th ed. Upper Saddle River, NJ: Pearson Education; 2013.

Author’s Last name, First name. “Chapter Title.” In: Editor’s Last name, First name, ed. Book Title. Edition number. Place of Publication: Publisher; Year: page numbers.

Example : Maidment, D. R. “Floodplain Management in the United States.” In: Shroder, J. F., ed. Treatise on Geomorphology. San Diego, CA: Academic Press; 2013: 447-460.

Author’s Last name, First name. “Paper Title.” In: Conference Title; Conference Date; Location. Place of Publication: Publisher; Year: page numbers.

Example: Smith, J. R. “Sustainable Drainage Systems for Urban Areas.” In: Proceedings of the ASCE International Conference on Sustainable Infrastructure; November 6-9, 2019; Los Angeles, CA. Reston, VA: American Society of Civil Engineers; 2019: 156-163.

Author’s Last name, First name. “Report Title.” Report number. Place of Publication: Publisher; Year.

Example : U.S. Army Corps of Engineers. “Hurricane Sandy Coastal Risk Reduction Program, New York and New Jersey.” Report No. P-15-001. Washington, DC: U.S. Army Corps of Engineers; 2015.

CSE (Council of Science Editors) Style

The CSE (Council of Science Editors) style is commonly used in the scientific and medical fields. Here are the different reference formats in CSE style:

Author’s Last name, First Initial. Middle Initial. “Article Title.” Journal Title. Year;Volume(Issue):Page numbers.

Example : Smith, J.R. “Evaluation of the Effectiveness of Sustainable Drainage Systems in Urban Areas.” Journal of Environmental Engineering. 2020;146(3):04020010.

Author’s Last name, First Initial. Middle Initial. Book Title. Edition number. Place of Publication: Publisher; Year.

Author’s Last name, First Initial. Middle Initial. “Chapter Title.” In: Editor’s Last name, First Initial. Middle Initial., ed. Book Title. Edition number. Place of Publication: Publisher; Year:Page numbers.

Author’s Last name, First Initial. Middle Initial. “Paper Title.” In: Conference Title; Conference Date; Location. Place of Publication: Publisher; Year.

Example : Smith, J.R. “Sustainable Drainage Systems for Urban Areas.” In: Proceedings of the ASCE International Conference on Sustainable Infrastructure; November 6-9, 2019; Los Angeles, CA. Reston, VA: American Society of Civil Engineers; 2019.

Author’s Last name, First Initial. Middle Initial. “Report Title.” Report number. Place of Publication: Publisher; Year.

Bluebook Style

The Bluebook style is commonly used in the legal field for citing legal documents and sources. Here are the different reference formats in Bluebook style:

Case citation

Case name, volume source page (Court year).

Example : Brown v. Board of Education, 347 U.S. 483 (1954).

Statute citation

Name of Act, volume source § section number (year).

Example : Clean Air Act, 42 U.S.C. § 7401 (1963).

Regulation citation

Name of regulation, volume source § section number (year).

Example: Clean Air Act, 40 C.F.R. § 52.01 (2019).

Book citation

Author’s Last name, First Initial. Middle Initial. Book Title. Edition number (if applicable). Place of Publication: Publisher; Year.

Example: Smith, J.R. Legal Writing and Analysis. 3rd ed. New York, NY: Aspen Publishers; 2015.

Journal article citation

Author’s Last name, First Initial. Middle Initial. “Article Title.” Journal Title. Volume number (year): first page-last page.

Example: Garcia, C. “The Right to Counsel: An International Comparison.” International Journal of Legal Information. 43 (2015): 63-94.

Website citation

Author’s Last name, First Initial. Middle Initial. “Page Title.” Website Title. URL (accessed month day, year).

Example : United Nations. “Universal Declaration of Human Rights.” United Nations. https://www.un.org/en/universal-declaration-human-rights/ (accessed January 3, 2023).

Oxford Style

The Oxford style, also known as the Oxford referencing system or the documentary-note citation system, is commonly used in the humanities, including literature, history, and philosophy. Here are the different reference formats in Oxford style:

Author’s Last name, First name. Book Title. Place of Publication: Publisher, Year of Publication.

Example : Smith, John. The Art of Writing. New York: Penguin, 2020.

Author’s Last name, First name. “Article Title.” Journal Title volume, no. issue (year): page range.

Example: Garcia, Carlos. “The Role of Ethics in Philosophy.” Philosophy Today 67, no. 3 (2019): 53-68.

Chapter in an edited book citation

Author’s Last name, First name. “Chapter Title.” In Book Title, edited by Editor’s Name, page range. Place of Publication: Publisher, Year of Publication.

Example : Lee, Mary. “Feminism in the 21st Century.” In The Oxford Handbook of Feminism, edited by Jane Smith, 51-69. Oxford: Oxford University Press, 2018.

Author’s Last name, First name. “Page Title.” Website Title. URL (accessed day month year).

Example : Jones, David. “The Importance of Learning Languages.” Oxford Language Center. https://www.oxfordlanguagecenter.com/importance-of-learning-languages/ (accessed 3 January 2023).

Dissertation or thesis citation

Author’s Last name, First name. “Title of Dissertation/Thesis.” PhD diss., University Name, Year of Publication.

Example : Brown, Susan. “The Art of Storytelling in American Literature.” PhD diss., University of Oxford, 2020.

Newspaper article citation

Author’s Last name, First name. “Article Title.” Newspaper Title, Month Day, Year.

Example : Robinson, Andrew. “New Developments in Climate Change Research.” The Guardian, September 15, 2022.

AAA (American Anthropological Association) Style

The American Anthropological Association (AAA) style is commonly used in anthropology research papers and journals. Here are the different reference formats in AAA style:

Author’s Last name, First name. Year of Publication. Book Title. Place of Publication: Publisher.

Example : Smith, John. 2019. The Anthropology of Food. New York: Routledge.

Author’s Last name, First name. Year of Publication. “Article Title.” Journal Title volume, no. issue: page range.

Example : Garcia, Carlos. 2021. “The Role of Ethics in Anthropology.” American Anthropologist 123, no. 2: 237-251.

Author’s Last name, First name. Year of Publication. “Chapter Title.” In Book Title, edited by Editor’s Name, page range. Place of Publication: Publisher.

Example: Lee, Mary. 2018. “Feminism in Anthropology.” In The Oxford Handbook of Feminism, edited by Jane Smith, 51-69. Oxford: Oxford University Press.

Author’s Last name, First name. Year of Publication. “Page Title.” Website Title. URL (accessed day month year).

Example : Jones, David. 2020. “The Importance of Learning Languages.” Oxford Language Center. https://www.oxfordlanguagecenter.com/importance-of-learning-languages/ (accessed January 3, 2023).

Author’s Last name, First name. Year of Publication. “Title of Dissertation/Thesis.” PhD diss., University Name.

Example : Brown, Susan. 2022. “The Art of Storytelling in Anthropology.” PhD diss., University of California, Berkeley.

Author’s Last name, First name. Year of Publication. “Article Title.” Newspaper Title, Month Day.

Example : Robinson, Andrew. 2021. “New Developments in Anthropology Research.” The Guardian, September 15.

AIP (American Institute of Physics) Style

The American Institute of Physics (AIP) style is commonly used in physics research papers and journals. Here are the different reference formats in AIP style:

Example : Johnson, S. D. 2021. “Quantum Computing and Information.” Journal of Applied Physics 129, no. 4: 043102.

Example : Feynman, Richard. 2018. The Feynman Lectures on Physics. New York: Basic Books.

Example : Jones, David. 2020. “The Future of Quantum Computing.” In The Handbook of Physics, edited by John Smith, 125-136. Oxford: Oxford University Press.

Conference proceedings citation

Author’s Last name, First name. Year of Publication. “Title of Paper.” Proceedings of Conference Name, date and location: page range. Place of Publication: Publisher.

Example : Chen, Wei. 2019. “The Applications of Nanotechnology in Solar Cells.” Proceedings of the 8th International Conference on Nanotechnology, July 15-17, Tokyo, Japan: 224-229. New York: AIP Publishing.

Example : American Institute of Physics. 2022. “About AIP Publishing.” AIP Publishing. https://publishing.aip.org/about-aip-publishing/ (accessed January 3, 2023).

Patent citation

Author’s Last name, First name. Year of Publication. Patent Number.

Example : Smith, John. 2018. US Patent 9,873,644.

References Writing Guide

Here are some general guidelines for writing references:

• Follow the citation style guidelines: Different disciplines and journals may require different citation styles (e.g., APA, MLA, Chicago). It is important to follow the specific guidelines for the citation style required.
• Include all necessary information : Each citation should include enough information for readers to locate the source. For example, a journal article citation should include the author(s), title of the article, journal title, volume number, issue number, page numbers, and publication year.
• Use proper formatting: Citation styles typically have specific formatting requirements for different types of sources. Make sure to follow the proper formatting for each citation.
• Order citations alphabetically: If listing multiple sources, they should be listed alphabetically by the author’s last name.
• Be consistent: Use the same citation style throughout the entire paper or project.
• Check for accuracy: Double-check all citations to ensure accuracy, including correct spelling of author names and publication information.
• Use reputable sources: When selecting sources to cite, choose reputable and authoritative sources. Avoid sources that are biased or unreliable.
• Include all sources: Make sure to include all sources used in the research, including those that were not directly quoted but still informed the work.
• Use online tools : There are online tools available (e.g., citation generators) that can help with formatting and organizing references.

Purpose of References in Research

References in research serve several purposes:

• To give credit to the original authors or sources of information used in the research. It is important to acknowledge the work of others and avoid plagiarism.
• To provide evidence for the claims made in the research. References can support the arguments, hypotheses, or conclusions presented in the research by citing relevant studies, data, or theories.
• To allow readers to find and verify the sources used in the research. References provide the necessary information for readers to locate and access the sources cited in the research, which allows them to evaluate the quality and reliability of the information presented.
• To situate the research within the broader context of the field. References can show how the research builds on or contributes to the existing body of knowledge, and can help readers to identify gaps in the literature that the research seeks to address.

Importance of References in Research

References play an important role in research for several reasons:

• Credibility : By citing authoritative sources, references lend credibility to the research and its claims. They provide evidence that the research is based on a sound foundation of knowledge and has been carefully researched.
• Avoidance of Plagiarism : References help researchers avoid plagiarism by giving credit to the original authors or sources of information. This is important for ethical reasons and also to avoid legal repercussions.
• Reproducibility : References allow others to reproduce the research by providing detailed information on the sources used. This is important for verification of the research and for others to build on the work.
• Context : References provide context for the research by situating it within the broader body of knowledge in the field. They help researchers to understand where their work fits in and how it builds on or contributes to existing knowledge.
• Evaluation : References provide a means for others to evaluate the research by allowing them to assess the quality and reliability of the sources used.

Advantages of References in Research

There are several advantages of including references in research:

• Acknowledgment of Sources: Including references gives credit to the authors or sources of information used in the research. This is important to acknowledge the original work and avoid plagiarism.
• Evidence and Support : References can provide evidence to support the arguments, hypotheses, or conclusions presented in the research. This can add credibility and strength to the research.
• Reproducibility : References provide the necessary information for others to reproduce the research. This is important for the verification of the research and for others to build on the work.
• Context : References can help to situate the research within the broader body of knowledge in the field. This helps researchers to understand where their work fits in and how it builds on or contributes to existing knowledge.
• Evaluation : Including references allows others to evaluate the research by providing a means to assess the quality and reliability of the sources used.
• Ongoing Conversation: References allow researchers to engage in ongoing conversations and debates within their fields. They can show how the research builds on or contributes to the existing body of knowledge.

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Write it Right - A guide to Harvard referencing style

• Referencing
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The Reference List

Differences between a reference list and a bibliography, compiling your reference list or bibliography.

• Elements in References
• Journal articles
• Online journals
• Newspaper articles
• Online newspapers
• Internet sources
• Government and legal publications
• Patents and standards
• Miscellaneous
• The reference list is a detailed list of all the sources that you have cited within your work, including books, eBooks, journal articles, theses, webpages etc. 
• Items are listed in alphabetical order in the reference list according to the main author/editor’s surname.
• This means that regardless of the order in which the in-text citations appear within your work, these items are all listed alphabetically by author/editor in the reference list. 
• This explains why the Harvard referencing style is also known as the ‘author-date’ style.
• The reference list is an alphabetical list of all the sources that you cited in the text of your assignment. 
• A bibliography is a separate list, presented in the same format as a reference list, however, it includes all the sources you consulted in the preparation of your assignment, not just those you cited. 
• In other words, a bibliography presents the same items as a reference list, but it also includes references to all the additional research you carried out, so it shows your extra effort. 
• All in-text references must be included in an alphabetical list, by author/editor’s surname, at the end of the work. As stated earlier, this is known as the reference list. A bibliography is a list of all works you used in preparation of the work, but which were not necessarily cited/referred to.
• This list must not be numbered.
• When there is no author/editor, use the title (book, journal, newspaper etc.)
• References in your reference list must be a full description of the in–text citations.
• If there is more than one publication by the same author, arrange the works in chronological order.
• In your reference list/bibliography the following abbreviations are accepted:

- (ed.) editor  - (eds) editors  - col. column - comp(s). compiler/compilers - edn. edition - et al. and others - n.d. no knowledge of the date - no. number - par. paragraph - s.l. no place of publication - s.n. publisher unknown - vol. volume

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A Quick Guide to Harvard Referencing | Citation Examples

Published on 14 February 2020 by Jack Caulfield . Revised on 15 September 2023.

Referencing is an important part of academic writing. It tells your readers what sources you’ve used and how to find them.

Harvard is the most common referencing style used in UK universities. In Harvard style, the author and year are cited in-text, and full details of the source are given in a reference list .

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Table of contents

Harvard in-text citation, creating a harvard reference list, harvard referencing examples, referencing sources with no author or date, frequently asked questions about harvard referencing.

A Harvard in-text citation appears in brackets beside any quotation or paraphrase of a source. It gives the last name of the author(s) and the year of publication, as well as a page number or range locating the passage referenced, if applicable:

Note that ‘p.’ is used for a single page, ‘pp.’ for multiple pages (e.g. ‘pp. 1–5’).

An in-text citation usually appears immediately after the quotation or paraphrase in question. It may also appear at the end of the relevant sentence, as long as it’s clear what it refers to.

When your sentence already mentions the name of the author, it should not be repeated in the citation:

Sources with multiple authors

When you cite a source with up to three authors, cite all authors’ names. For four or more authors, list only the first name, followed by ‘ et al. ’:

Sources with no page numbers

Some sources, such as websites , often don’t have page numbers. If the source is a short text, you can simply leave out the page number. With longer sources, you can use an alternate locator such as a subheading or paragraph number if you need to specify where to find the quote:

Multiple citations at the same point

When you need multiple citations to appear at the same point in your text – for example, when you refer to several sources with one phrase – you can present them in the same set of brackets, separated by semicolons. List them in order of publication date:

Multiple sources with the same author and date

If you cite multiple sources by the same author which were published in the same year, it’s important to distinguish between them in your citations. To do this, insert an ‘a’ after the year in the first one you reference, a ‘b’ in the second, and so on:

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A bibliography or reference list appears at the end of your text. It lists all your sources in alphabetical order by the author’s last name, giving complete information so that the reader can look them up if necessary.

The reference entry starts with the author’s last name followed by initial(s). Only the first word of the title is capitalised (as well as any proper nouns).

Sources with multiple authors in the reference list

As with in-text citations, up to three authors should be listed; when there are four or more, list only the first author followed by ‘ et al. ’:

Reference list entries vary according to source type, since different information is relevant for different sources. Formats and examples for the most commonly used source types are given below.

• Entire book
• Book chapter
• Translated book
• Edition of a book

Journal articles

• Print journal
• Online-only journal with DOI
• Online-only journal with no DOI

• General web page
• Online article or blog
• Social media post

Sometimes you won’t have all the information you need for a reference. This section covers what to do when a source lacks a publication date or named author.

No publication date

When a source doesn’t have a clear publication date – for example, a constantly updated reference source like Wikipedia or an obscure historical document which can’t be accurately dated – you can replace it with the words ‘no date’:

Note that when you do this with an online source, you should still include an access date, as in the example.

When a source lacks a clearly identified author, there’s often an appropriate corporate source – the organisation responsible for the source – whom you can credit as author instead, as in the Google and Wikipedia examples above.

When that’s not the case, you can just replace it with the title of the source in both the in-text citation and the reference list:

Harvard referencing uses an author–date system. Sources are cited by the author’s last name and the publication year in brackets. Each Harvard in-text citation corresponds to an entry in the alphabetised reference list at the end of the paper.

Vancouver referencing uses a numerical system. Sources are cited by a number in parentheses or superscript. Each number corresponds to a full reference at the end of the paper.

A Harvard in-text citation should appear in brackets every time you quote, paraphrase, or refer to information from a source.

The citation can appear immediately after the quotation or paraphrase, or at the end of the sentence. If you’re quoting, place the citation outside of the quotation marks but before any other punctuation like a comma or full stop.

In Harvard referencing, up to three author names are included in an in-text citation or reference list entry. When there are four or more authors, include only the first, followed by ‘ et al. ’

Though the terms are sometimes used interchangeably, there is a difference in meaning:

• A reference list only includes sources cited in the text – every entry corresponds to an in-text citation .
• A bibliography also includes other sources which were consulted during the research but not cited.

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Caulfield, J. (2023, September 15). A Quick Guide to Harvard Referencing | Citation Examples. Scribbr. Retrieved 7 June 2024, from https://www.scribbr.co.uk/referencing/harvard-style/

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Referencing

Referencing is one of the most important aspects of any academic research and poor or lack of referencing will not only diminish your marks, but such practices may also be perceived as plagiarism by your university and disciplinary actions may follow that may even result in expulsion from the course.

Difference between References and Bibliography

It is very important to be able to distinguish between References and Bibliography. Under References you list resources that you referred to within the body of the work that also include quotations.  For example,

It has been noted that “time and the management of time is an important issue, and the supply of time management products – books, articles, CDs, workshops, etc. – reflects the huge demand for these products” (Walsh, 2007, p.3).

Interchangeability of identical parts and a high level of straightforwardness of attaching these parts through the assembly line can be considered as revolutionary components of Fordism for the first part of the 20 th century (Nolan, 2008).

Under Bibliography, on the other hand, you need to list resources that you have read during the research process in order to widen your knowledge about the research area , but specific piece of information from these resources have not been used in your research in the direct manner. You do not need to refer to Bibliography within the body of the text.

There are various methods of referencing such as Harvard, APA and Vancouver referencing systems. You should check with your dissertation handbook for the exact type of referencing required and follow this requirement thoroughly.

John Dudovskiy

Citation Guide

• What is a Citation?
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What is a Bibliography?

What is an annotated bibliography, introduction to the annotated bibliography.

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• the authors' names
• the titles of the works
• the names and locations of the companies that published your copies of the sources
• the dates your copies were published
• the page numbers of your sources (if they are part of multi-source volumes)

Ok, so what's an Annotated Bibliography?

An annotated bibliography is the same as a bibliography with one important difference: in an annotated bibliography, the bibliographic information is followed by a brief description of the content, quality, and usefulness of the source. For more, see the section at the bottom of this page.

What are Footnotes?

Footnotes are notes placed at the bottom of a page. They cite references or comment on a designated part of the text above it. For example, say you want to add an interesting comment to a sentence you have written, but the comment is not directly related to the argument of your paragraph. In this case, you could add the symbol for a footnote. Then, at the bottom of the page you could reprint the symbol and insert your comment. Here is an example:

This is an illustration of a footnote. 1 The number “1” at the end of the previous sentence corresponds with the note below. See how it fits in the body of the text? 1 At the bottom of the page you can insert your comments about the sentence preceding the footnote.

When your reader comes across the footnote in the main text of your paper, he or she could look down at your comments right away, or else continue reading the paragraph and read your comments at the end. Because this makes it convenient for your reader, most citation styles require that you use either footnotes or endnotes in your paper. Some, however, allow you to make parenthetical references (author, date) in the body of your work.

Footnotes are not just for interesting comments, however. Sometimes they simply refer to relevant sources -- they let your reader know where certain material came from, or where they can look for other sources on the subject. To decide whether you should cite your sources in footnotes or in the body of your paper, you should ask your instructor or see our section on citation styles.

Where does the little footnote mark go?

Whenever possible, put the footnote at the end of a sentence, immediately following the period or whatever punctuation mark completes that sentence. Skip two spaces after the footnote before you begin the next sentence. If you must include the footnote in the middle of a sentence for the sake of clarity, or because the sentence has more than one footnote (try to avoid this!), try to put it at the end of the most relevant phrase, after a comma or other punctuation mark. Otherwise, put it right at the end of the most relevant word. If the footnote is not at the end of a sentence, skip only one space after it.

What's the difference between Footnotes and Endnotes?

The only real difference is placement -- footnotes appear at the bottom of the relevant page, while endnotes all appear at the end of your document. If you want your reader to read your notes right away, footnotes are more likely to get your reader's attention. Endnotes, on the other hand, are less intrusive and will not interrupt the flow of your paper.

If I cite sources in the Footnotes (or Endnotes), how's that different from a Bibliography?

Sometimes you may be asked to include these -- especially if you have used a parenthetical style of citation. A "works cited" page is a list of all the works from which you have borrowed material. Your reader may find this more convenient than footnotes or endnotes because he or she will not have to wade through all of the comments and other information in order to see the sources from which you drew your material. A "works consulted" page is a complement to a "works cited" page, listing all of the works you used, whether they were useful or not.

Isn't a "works consulted" page the same as a "bibliography," then?

Well, yes. The title is different because "works consulted" pages are meant to complement "works cited" pages, and bibliographies may list other relevant sources in addition to those mentioned in footnotes or endnotes. Choosing to title your bibliography "Works Consulted" or "Selected Bibliography" may help specify the relevance of the sources listed.

This information has been freely provided by plagiarism.org and can be reproduced without the need to obtain any further permission as long as the URL of the original article/information is cited. 

How Do I Cite Sources? (n.d.) Retrieved October 19, 2009, from http://www.plagiarism.org/plag_article_how_do_i_cite_sources.html

The Importance of an Annotated Bibliography

An Annotated Bibliography is a collection of annotated citations. These annotations contain your executive notes on a source. Use the annotated bibliography to help remind you of later of the important parts of an article or book. Putting the effort into making good notes will pay dividends when it comes to writing a paper!

Good Summary

Being an executive summary, the annotated citation should be fairly brief, usually no more than one page, double spaced.

• Focus on summarizing the source in your own words.
• Avoid direct quotations from the source, at least those longer than a few words. However, if you do quote, remember to use quotation marks. You don't want to forget later on what is your own summary and what is a direct quotation!
• If an author uses a particular term or phrase that is important to the article, use that phrase within quotation marks. Remember that whenever you quote, you must explain the meaning and context of the quoted word or text. 

Common Elements of an Annotated Citation

• Summary of an Article or Book's thesis or most important points (Usually two to four sentences)
• Summary of a source's methodological approach. That is, what is the source? How does it go about proving its point(s)? Is it mostly opinion based? If it is a scholarly source, describe the research method (study, etc.) that the author used. (Usually two to five sentences)
• Your own notes and observations on the source beyond the summary. Include your initial analysis here. For example, how will you use this source? Perhaps you would write something like, "I will use this source to support my point about . . . "
• Formatting Annotated Bibliographies This guide from Purdue OWL provides examples of an annotated citation in MLA and APA formats.

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Citation Styles Guide | Examples for All Major Styles

Published on June 24, 2022 by Jack Caulfield . Revised on November 7, 2022.

A citation style is a set of guidelines on how to cite sources in your academic writing . You always need a citation whenever you quote , paraphrase , or summarize a source to avoid plagiarism . How you present these citations depends on the style you follow. Scribbr’s citation generator can help!

Different styles are set by different universities, academic associations, and publishers, often published in an official handbook with in-depth instructions and examples.

There are many different citation styles, but they typically use one of three basic approaches: parenthetical citations , numerical citations, or note citations.

Parenthetical citations

• Chicago (Turabian) author-date

CSE name-year

Numerical citations

CSE citation-name or citation-sequence

Note citations

• Chicago (Turabian) notes and bibliography

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Types of citation: parenthetical, note, numerical, which citation style should i use, parenthetical citation styles, numerical citation styles, note citation styles, frequently asked questions about citation styles.

The clearest identifying characteristic of any citation style is how the citations in the text are presented. There are three main approaches:

• Parenthetical citations: You include identifying details of the source in parentheses in the text—usually the author’s last name and the publication date, plus a page number if relevant ( author-date ). Sometimes the publication date is omitted ( author-page ).
• Numerical citations: You include a number in brackets or in superscript, which corresponds to an entry in your numbered reference list.
• Note citations: You include a full citation in a footnote or endnote, which is indicated in the text with a superscript number or symbol.

Citation styles also differ in terms of how you format the reference list or bibliography entries themselves (e.g., capitalization, order of information, use of italics). And many style guides also provide guidance on more general issues like text formatting, punctuation, and numbers.

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In most cases, your university, department, or instructor will tell you which citation style you need to follow in your writing. If you’re not sure, it’s best to consult your institution’s guidelines or ask someone. If you’re submitting to a journal, they will usually require a specific style.

Sometimes, the choice of citation style may be left up to you. In those cases, you can base your decision on which citation styles are commonly used in your field. Try reading other articles from your discipline to see how they cite their sources, or consult the table below.

The American Anthropological Association (AAA) recommends citing your sources using Chicago author-date style . AAA style doesn’t have its own separate rules. This style is used in the field of anthropology.

APA Style is defined by the 7th edition of the Publication Manual of the American Psychological Association . It was designed for use in psychology, but today it’s widely used across various disciplines, especially in the social sciences.

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The citation style of the American Political Science Association (APSA) is used mainly in the field of political science.

The citation style of the American Sociological Association (ASA) is used primarily in the discipline of sociology.

Chicago author-date

Chicago author-date style is one of the two citation styles presented in the Chicago Manual of Style (17th edition). It’s used mainly in the sciences and social sciences.

The citation style of the Council of Science Editors (CSE) is used in various scientific disciplines. It includes multiple options for citing your sources, including the name-year system.

Harvard style is often used in the field of economics. It is also very widely used across disciplines in UK universities. There are various versions of Harvard style defined by different universities—it’s not a style with one definitive style guide.

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MLA style is the official style of the Modern Language Association, defined in the MLA Handbook (9th edition). It’s widely used across various humanities disciplines. Unlike most parenthetical citation styles, it’s author-page rather than author-date.

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The American Chemical Society (ACS) provides guidelines for a citation style using numbers in superscript or italics in the text, corresponding to entries in a numbered reference list at the end. It is used in chemistry.

The American Medical Association ( AMA ) provides guidelines for a numerical citation style using superscript numbers in the text, which correspond to entries in a numbered reference list. It is used in the field of medicine.

CSE style includes multiple options for citing your sources, including the citation-name and citation-sequence systems. Your references are listed alphabetically in the citation-name system; in the citation-sequence system, they appear in the order in which you cited them.

The Institute of Electrical and Electronics Engineers ( IEEE ) provides guidelines for citing your sources with IEEE in-text citations that consist of numbers enclosed in brackets, corresponding to entries in a numbered reference list. This style is used in various engineering and IT disciplines.

The National Library of Medicine (NLM) citation style is defined in Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers (2nd edition).

Vancouver style is also used in various medical disciplines. As with Harvard style, a lot of institutions and publications have their own versions of Vancouver—it doesn’t have one fixed style guide.

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The Bluebook: A Uniform System of Citation is the main style guide for legal citations in the US. It’s widely used in law, and also when legal materials need to be cited in other disciplines.

Chicago notes and bibliography

Chicago notes and bibliography is one of the two citation styles presented in the Chicago Manual of Style (17th edition). It’s used mainly in the humanities.

The Oxford University Standard for the Citation of Legal Authorities ( OSCOLA ) is the main legal citation style in the UK (similar to Bluebook for the US).

There are many different citation styles used across different academic disciplines, but they fall into three basic approaches to citation:

• Parenthetical citations : Including identifying details of the source in parentheses —usually the author’s last name and the publication date, plus a page number if available ( author-date ). The publication date is occasionally omitted ( author-page ).
• Numerical citations: Including a number in brackets or superscript, corresponding to an entry in your numbered reference list.
• Note citations: Including a full citation in a footnote or endnote , which is indicated in the text with a superscript number or symbol.

Check if your university or course guidelines specify which citation style to use. If the choice is left up to you, consider which style is most commonly used in your field.

• APA Style is the most popular citation style, widely used in the social and behavioral sciences.
• MLA style is the second most popular, used mainly in the humanities.
• Chicago notes and bibliography style is also popular in the humanities, especially history.
• Chicago author-date style tends to be used in the sciences.

Other more specialized styles exist for certain fields, such as Bluebook and OSCOLA for law.

The most important thing is to choose one style and use it consistently throughout your text.

A scientific citation style is a system of source citation that is used in scientific disciplines. Some commonly used scientific citation styles are:

• Chicago author-date , CSE , and Harvard , used across various sciences
• ACS , used in chemistry
• AMA , NLM , and Vancouver , used in medicine and related disciplines
• AAA , APA , and ASA , commonly used in the social sciences

APA format is widely used by professionals, researchers, and students in the social and behavioral sciences, including fields like education, psychology, and business.

Be sure to check the guidelines of your university or the journal you want to be published in to double-check which style you should be using.

MLA Style  is the second most used citation style (after APA ). It is mainly used by students and researchers in humanities fields such as literature, languages, and philosophy.

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The art of referencing: Well begun is half done!

Department of Pediatrics, College of Medicine and Health Sciences, National University of Science and Technology, Sohar, Sultanate of Oman

Department of Pediatrics, Seth G.S. Medical College and K.E.M. Hospital, Mumbai, Maharashtra, India

Introduction

The value of scientific research lies in its wide visibility and access/availability to others; this is generally achieved by a scientific publication as an original (research) paper. The scientific inquiry typically advances based on previously laid ideas/research, making it essential to acknowledge the contribution of the previous authors. The references list is a catalog of literature sources chosen by the researcher to represent the most relevant documents pertaining to his/her study.[ 1 ] The British Standards Institution defines reference as “a set of data describing a document, sufficiently precise and detailed to identify it and enable it to be located.” [ 2 ] References lay the foundation of the paper, providing context for the hypothesis, methodology, interpretation, and justification of the study.[ 3 ] Using other's ideas/thoughts without due credit amounts to plagiarism, compromising the academic integrity of research. A well-referenced paper is thus accurate and complete, adds value and credibility to both the researcher and the source author, and enhances the scientific prestige of the chosen journal.[ 3 ] A bibliography also lists the sources used during research. However, while references only include those sources (journals, books, web information, etc.) which are actually cited in the publication, bibliography comprises all accessed sources (works consulted), irrespective of whether they are cited in the study publication or not.[ 4 ] Thus, referencing in academic writing is an important research tool to display as well as integrate knowledge on a particular subject or topic.[ 5 ]

Importance of Proper Referencing

Scientific research is usually developed on previously established ideas/scientific knowledge. A meticulous literature review at the beginning of the study enables the researcher to identify the work done in the field, identify the gaps in knowledge, and recognize the need for further research.[ 6 ] The most relevant sources from this literature search (essentially) form the list of references. Use of proper referencing is thus beneficial in many ways, such as the following:

• a) It helps the readers to identify and locate the sources used in the research and provides evidence to verify the need/rationale of the study, methodology, inferences, and implications of the study.[ 3 ]
• b) It provides an overview of the techniques/tools used, supports/convinces the reader about the appropriateness of the methodology, and offers a proper perspective in which the research findings need to be interpreted.[ 3 , 7 ]
• c) It is a proof of the author's in-depth reading and knowledge on the subject pertaining to his/her research. References not only highlight similarities in research, but also differentiate the author's ideas from his sources, indirectly acknowledging the author's own contribution to that topic.[ 4 ]
• d) References chosen by a researcher not only credit the individual author/s whose work is cited, but also demonstrate his/her appreciation toward cited authors, at times leading readers toward hitherto lesser-known/unknown author's research.[ 4 , 8 ] By providing acknowledgment to the cited idea/thought, the author also avoids being accused of plagiarism and adds credibility to his/her own work.[ 4 ]
• e) Referenced works steer the readers toward literature pertaining to a particular topic, thus advancing the readers’ interest.[ 4 ] It also allows to trace the origins of ideas and integrates newer ideas (from current research) with previous ones, thus building a web of learning about the topic of interest.[ 9 ]
• f) The reference list provides a list of experts in a specific field, thus helping editors to identify appropriate reviewers.[ 3 ]
• g) It provides peer reviewers with related sources of information to evaluate the manuscript with respect to the cited work.[ 6 ]

Organizing the References

An initial extensive literature search helps in identifying the appropriate research question, drafting the study protocol, supervising ongoing research, analyzing the results, and writing the paper.[ 3 , 7 ] Although references are displayed at the end of the article/after the text of the article, they should not be actually written after completing the text of the manuscript. While drafting the text of the manuscript, the author/s should type the references on a separate MS Word document simultaneously. This preparation allows the writer to choose adequate number of relevant and rational references, avoid bias in his/her research/writing, and limit the reference number as per the target journal for publication.[ 7 ] While citing, it is imperative not to cite broadly, but to do so with respect to the content of the article. Articles which define the topic, lay down background information regarding the study question, give current knowledge about the research, and describe previous studies on a similar study question should be mentioned in the “Introduction” section of the manuscript.[ 10 ] These studies enable to identify existing knowledge, gaps in knowledge, and justify the rationale of the study.[ 6 ] Studies which identify or refer to the method, protocols, or standards (whether new or previously published), elaborate on complex or lesser-known statistical analysis, describe diagnostic criteria, rationalize sample size estimation, or justify use of specific study design/method are best suited as references to the “Methods” section of the manuscript – they help to plan a strong and supported methodology and describe the technique and criteria of the study group.[ 3 , 10 ] Research that reflects on the study findings/results or provides supportive explanation merit mention in the “Discussion” section of the manuscript – they provide information to interpret the study based on existing published data, compare results with those of other studies, and rationalize the implications of the results.[ 10 ]

Though citation analysis treats all references equally, it is important to weigh references in terms of their value to the paper.[ 11 ] While some references are worthy to be mentioned only once in the paper, some are very relevant to the study question and referred to on multiple occasions, and it is important to re-cite only the most relevant articles.[ 3 ] Referencing is not just about stating the publication source (providing relatedness), but also adds value to the paper in terms of representation on the subject and connectivity between knowledge sources (capture the “aboutness”).[ 11 ] References can be books (author/s), legal documents, journal articles, newspaper articles, reports (e.g., official reports from government departments), university working papers, papers presented at conferences, internet sources (including weblogs – blogs and email correspondence), DVD/CD databases, radio/television/videos/audio cassette/CD-ROMs, interview transcripts, and illustrations.[ 12 ]

Choosing Appropriate References

As a rule, whenever one uses an idea, data, diagrams, tables, concepts, methods from a previously published work, it should be cited.[ 12 ] With availability of multiple search engines and abundance of online resources, the task of filtering references may seem daunting.[ 5 ] While choosing references, one should ensure that the original source is completely read and correctly interpreted before its citing.[ 6 ] It is preferable to provide direct references to original article sources as far as possible, choosing a landmark article on the topic.[ 5 ] The choice of references should serve as the most relevant, appropriate, and valuable addition, and one should stick to the most pertinent references that actively support/contradict their conclusions or experience.[ 6 ] It is preferable to use the most recent relevant resources to provide the latest and up-to-date information; however, certain landmark papers may also be cited (even if they are old). Note that very old references may not be available/accessible to reviewers as well as readers.[ 7 ] Often, there are multiple sources for the same information; always prefer references that provide the highest level of evidence (such as meta-analysis), most recent publications, or trustworthy sources such as reputed peer-reviewed journals (with higher impact factor), open access and preferably indexed on reputed databases such as MEDLINE and PubMed.[ 13 , 14 ] Citing works from the journal one wishes to submit demonstrates that author follows that particular journal's publications and values it; however, one should refrain from unethical practices such as coercive citation (when authors are coerced/directed to add irrelevant citations from the editor's journals) or padded citation (when authors pad their reference list with superfluous citations).[ 14 , 15 , 16 ] There should be a judicious combination of original as well as review articles. Review articles summarize a large body of literature and reduce the number of references; however they may be biased and may not reflect the original article accurately.[ 16 ] One should stick to the journal guidelines rigorously (in terms of style and number) to avoid rejection or delay in the processing of the manuscript.[ 6 ] Avoid citing conference abstracts as far as possible, as they provide incomplete or limited information on the subject and often lack an appropriate peer review.[ 16 ] Other sources which lack traditional review and thus may cite inappropriate, unchecked, or promotional content include online sources, such as audio and video presentations, and should therefore be used with caution.[ 17 ] It is also prudent to avoid personal communications and limit their use to situations where essential information is unavailable from a public source (if permission is necessary, then name and date of the communication should be cited in brackets in text).[ 16 ] Limit self-citations to the bare crucial ones that are necessary.[ 18 ] Articles accepted but awaiting publications should be cited as “in press.”[ 16 ] Articles submitted but not yet published should be referenced as “unpublished observations” with written permission from the source; however, since they have not undergone a peer review, they should be (preferably) avoided.[ 16 ] It is prudent to avoid citing articles published in predatory journals.[ 16 ]

There is no need to provide references to facts that are expected to be well known to the journal readers, including historical overviews, own experiences, while outlining previously referenced ideas in conclusions, or while summarizing what is regarded as “common knowledge.”[ 12 ] One should be careful with online sources. There may be errors while copying the uniform resource locator (URL) or the webpage, or the website may change or be closed/inaccessible; hence, cite them only if very essential and check for their reliability and give the date of access.[ 3 ] It is preferable to use online sources with digital object identifiers (DOIs), assuring their permanent presence.[ 13 ] Also, before submission, it is worthwhile to check the US National Library of Medicine's (NLM's) PubMed database ( http://www.pubmed.org ) for any recently published articles related to the manuscript's topic.[ 19 ]

The number of references is determined by the target journal requirements as well as the type of manuscript submitted; for example, the Journal of Postgraduate Medicine allows about 30 references for original articles, up to 15 references for brief reports/grand rounds/clinicopathological forum, 12 references for case series, up to 10 references for case reports/research letter, and five references for a letter to editor ( https://www.jpgmonline.com/contributors.asp#Ref ).

Preparing the References

Citation consists of two components – the “in-text citation” and the “reference list.”[ 7 ] In the in-text citation, quotation marks are used to cite an exact line/phrase from another source, specifically for definitions, examples, or explanations provided by another/earlier author/s.[ 13 ] To prevent plagiarism, it is suitable to interpret and then summarize the cited content in one's own words, referencing the source at the end of the sentence.[ 14 ]

The parts and order in the citation depend on the source which the author is referencing (journal, book, book chapter, or web source) and the journal guidelines. It is imperative to go through the target journal rules and follow the “Instructions to Authors” related to referencing guidelines (the style, punctuation, italics, abbreviations, issue number, volume number, and pages). All the references are generally cited and numbered as per the order in which they are mentioned in the text (and are to be inserted immediately after the source information and not necessarily at the end of the sentence, especially when multiple facts are stated in a single sentence).[ 6 ] In case of a table or a figure, the citation number should be in sequence to that of the preceding text.[ 7 ] The same reference number in which the source is first cited should be used throughout the manuscript (if cited again) as well as in the reference list.[ 7 ] The citation numbers are placed as superscript/in parentheses as per the journal guidelines.[ 7 ] In case of multiple citations, place them immediately after the fact; they should be placed in order of their chronology of publication (or alphabetically if published in the same year) separated by commas.[ 6 , 7 ] If many references are cited consecutively, the numbers can be separated by a hyphen.[ 7 ]

Any documented knowledge (text, audio, or visual) can serve as a source of reference. They can be print based or electronic and include journals, books, doctoral theses, conference papers, newspapers and magazines, web pages, and so on.[ 4 ]

The basic elements while referencing are as follows:[ 13 , 20 ]

• Journal/research paper: Name of author/s, title of paper, journal title (often abbreviated according to the style used for MEDLINE [ www.ncbi.nlm.nih.gov/nlmcatalog/journals ]),[ 16 ] publication year, volume number, issue number (issue number is kept optional by many journals), and page numbers (starting and ending page numbers or e-article number if the journal does not allot page numbers but allots e-article numbers only)[ 13 ]
• Book/chapter: Chapter author/s, title of chapter, editor/s, name of book, edition, publisher, city of publication, year of publication, and page numbers[ 13 ]
• Web sources: Names of author/s, title of webpage, year, weblink, date of access, and other information such as publisher, year of publication, and date of recent update (as may be applicable/available).[ 13 ] When citing a webpage, provide the DOI or URL of the original source as far as possible.[ 1 , 20 ]

Special attention needs to be paid to the punctuations while composing the reference, and the authors must adhere to the style recommended by the journal (that the manuscript will be eventually submitted to). Note that with each revision that the author makes in the manuscript, there may be changes in the order, addition, or deletion of references, and these adjustments should be meticulously ensured to avoid referencing errors.[ 3 ] It is also the author's responsibility to ensure that every citation has a corresponding reference and every reference is cited in the right place and context in the manuscript.[ 6 ] To avoid citation errors, the authors must verify each reference against an electronic bibliographic source like PubMed or print/pdf copies of original resources.[ 16 ] Authors should also verify that none of the cited references is a retracted article; this can be done via MEDLINE by searching PubMed for “Retracted publication [publication type]” or by going directly to the PubMed's list of retracted publications ( https://www.ncbi.nlm.nih.gov/pubmed/?termretractedpublication[publication type] ).[ 16 ]

“Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals” issued by the International Committee of Medical Journal Editors (ICMJE) provides specific information on how to cite sources, which should be followed.[ 16 ] These recommendations by the ICMJE summarize and provide regular updates on how to cite various sources (print documents; unpublished material; audio and visual media; material on CD-ROM, DVD, or disk; and material on the Internet) via Sample References ( www.nlm.nih.gov/bsd/uniform_requirements.html ) on their webpage.[ 16 ] Detailed information is also available in the NLM's Citing Medicine, 2 nd edition ( www.ncbi.nlm.nih.gov/books/NBK7256/ ).[ 20 ] Number of references to be cited should be in accordance with/within the limits as stated in the “Author Guidelines” issued by the target journal.[ 7 ] Authors should take precaution, so as to avoid citing the same reference twice in the list of references.

Types of Referencing Formats/Styles

“Citation style” is the standard format in which the source is documented in the text as well as in the reference list at the end of the manuscript.[ 4 ] In-text citation styles can be broadly classified into numerical referencing style (Numeric style/Vancouver/Institute of Electrical and Electronic Engineers [IEEE] and Running notes style/Modern Humanities Research Association [MHRA]) and name referencing style (Author Date/Harvard, American Psychological Association [APA] and Modern Languages Association [MLA]).[ 12 ] The two major used citation styles are the Vancouver and the Harvard styles, and most other styles are minor modifications of these two styles.[ 4 ] The common citation styles and their examples are summarized in Table 1 .[ 3 , 12 , 13 , 16 , 20 ] Thus, there is a wide variability in the citation style in text as well as reference list; however, the author does not have a choice, but to stick to the style recommended by the journal to which he/she wishes to submit his/her research.[ 3 ]

Citation styles with examples[ 3 , 12 , 13 , 16 , 20 ]

Common Errors in Referencing

Referencing is a tedious task and if not taken seriously and performed diligently, it is prone to many (easily avoidable) errors.[ 7 ] A reference should be accurate, clear, and consistent throughout the manuscript.[ 6 ] An incorrect reference not only questions the credibility of the paper, but also makes it difficult for the reviewers and the readers to seek the cited article, thus denying the source author of due credit for his/her work.[ 3 ] It is the author's responsibility to cite the most relevant and appropriate references in his/her research.[ 3 ] The author should not only locate, read, and understand all sources cited by him/her ( intellectual pleasure ), but also confirm the source and provide all elements of the source correctly ( accuracy ).[ 6 ] The author should be careful not to copy references from an earlier article, but should actually rewrite each selected reference afresh.[ 6 ] Some common errors occurring during referencing are summarized in Table 2 .[ 6 , 7 ]

Common errors in the “in-text citation” and the “reference list”[ 6 , 7 ]

Reference Management Software

As described earlier, there is a wide variation in the journal formatting styles and it is laborious for the researcher to store, organize, and manage the references throughout the process of literature review and protocol planning till the drafting and manuscript submission.[ 21 ] Even more challenging is the addition/deletion or reordering of references (in text as well as in the reference list) with each revision or submission to a newer journal.[ 22 ] There is an increased likelihood of making errors in citing, especially while organizing the references and writing the reference list.[ 23 ] To minimize such errors, reference management software (RMS), also known as citation management software or bibliographic management software, are available to the authors/researchers.[ 21 ] They not only help to search and retrieve the online scientific sources, but also help to import them to their database for storing, organization, and subsequent retrieval.[ 22 ] Many RMS have cloud-based storage, enabling users to be able to access the information from multiple devices as well as collaborate with other researchers.[ 22 ] RMS also allow authors to retrieve citations while writing in the format of desired journal, thus permitting to “cite while you write.”[ 14 ] They also enable addition, deletion, insertion of references in the text and automatic (auto) resequencing of their order in the main manuscript (text) as well as in the reference list.[ 22 ] They can generate reference lists in multiple formats/citation styles to suit the target journal requirements and allow conversion of one format style to another with ease at the click of the mouse.[ 14 ] By linking each citation with a full reference, they ensure each citation in the text is accounted for by a corresponding full reference in the list.[ 12 ] Most of them are compatible for use with common programs such as Microsoft Word and Google Docs.[ 24 ]

There are numerous programs for reference management available in the market – independent applications, those operating within an internet interface, and combination of both these modes.[ 1 ] The most commonly used are Mendeley by Elsevier ( www.mendeley.com ), EndNote ( www.endnote.com ) by Thomson Reuters, and Zotero ( www.zotero.org ).[ 1 ] Some others are RefWorks, F1000 Workspace, JabRef, Citavi, Bibsonomy, ReadCube Papers, Colwiz, Sente, RefME, Connotea, CiteULike, BibTeX, and Microsoft Word.[ 22 , 24 , 25 ] While many of them are free, some are fee based and require a (paid) subscription.[ 13 ]

Despite the use of RMS, one cannot guarantee absence of referencing errors, as there can be errors in details (author names, journal title, dates) or duplication of references when retrieved from different databases.[ 23 ] So, ultimately, the authors (themselves) are responsible for the accuracy of the references cited by them (whether they do the referencing using RMS or manually).

Thus, referencing is an essential part of research and should be assigned due importance, right from the conception of the study question till its delivery as a publication. It plays a vital role throughout the manuscript and appears in almost all sections – from laying down the foundation for study rationale (in the “Introduction” section of the manuscript), describing/justifying the study procedure/s (in the “Methods” section), validating the results (in the “Results” section) and its implications (in the “Discussion” section of the manuscript). References are also utilized by editors to identify subject experts for peer review, by readers to obtain more resources on the subject matter, and by peer reviewers to critically evaluate the manuscript in the light of the available evidence. It is thus essential that references are chosen wisely and carefully as they are representative of the study. It is the author's responsibility to confirm the clarity, accuracy, and appropriateness of the cited sources. One should be careful to avoid common referencing errors to prevent delay/rejection by the journal of interest. As Vancouver style is the commonly preferred citation style by journals of medicine and health sciences, researchers should be well versed with it. Authors should diligently stick to the instructions and style of the target journal. The availability of reference management software such as Mendeley and EndNote has made the authors’ task of collecting, storing, organizing, retrieving, and utilizing the references more efficient and easier; however, it is still the authors’ responsibility to select appropriate references and cite them accurately and correctly.

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Conflicts of interest.

There are no conflicts of interest.

• Key Differences

Know the Differences & Comparisons

Difference Between Reference and Bibliography

Reference and Bibliography is an important part of any project under study because it helps in acknowledging other’s work and also help the readers in finding the original sources of information. It not only prevents plagiarism but also indicates that the writer has done good research on the subject by using a variety of sources to gain information.

Read out the article to know the differences between reference and bibliography.

Content: Reference Vs Bibliography

Comparison chart.

Definition of Reference

Reference can be understood as the act of giving credit to or mentioning the name of, someone or something. In research methodology, it denotes the items which you have reviewed and referred to, in the text, in your research work. It is nothing but a way to acknowledge or indirectly showing gratitude, towards the sources from where the information is gathered.

While using references, one thing is to be noted that you go for reliable sources only, because it increases credence and also supports your arguments. It may include, books, research papers, or articles from magazines, journals, newspapers, etc., interview transcripts, internet sources such as websites, blogs, videos watched, and so forth.

These are used to inform the reader about the sources of direct quotations, tables, statistics, photos etc. that are included in the research work.

Definition of Bibliography

At the end of the research report, bibliography is added, which contains a list of books, magazines, journals, websites or other publications which are in some way relevant to the topic under study, that has been consulted by the researcher during the research. In finer terms, it comprises of all the references cited in the form of footnotes and other important works that the author has studied.

The bibliography is helpful to the reader in gaining information regarding the literature available on the topic and what influenced the author. For better presentation and convenient reading, the bibliography can be grouped into two parts, wherein the first part lists out the names of books and pamphlets consulted, and the other contains the names of magazines and newspapers considered.

Types of Bibliography

• Bibliography of works cited : It contains the name of those books whose content has been cited in the text of the research report.
• Selected Bibliography : As it is evident from the name itself, selected bibliography covers only those works which the author assumes that are of major interest to the reader.
• Annotated Bibliography : In this type of bibliography, a small description of the items covered is given by the author to ensure readability and also improve the usefulness of the book.

Key Differences Between Reference and Bibliography

The difference between reference and bibliography can be drawn clearly on the following grounds:

• Reference implies referring to someone or something, that means it provides the list of sources, whose text is used in the assignment or research work. Conversely, bibliography represents the list of all the sources, from which the research has gained some information about the topic, irrespective of the work cited or not.
• References are based on primary sources, whereas bibliography is created on the basis of primary and secondary sources.
• References used in the assignment can be arranged alphabetically or numerically. On the contrary, list of sources used in the bibliography is arranged numerically.
• The bibliography is used to list out everything you go through to obtain the information relating to the assignment, no matter if you specifically cite it in your assignment or not. Now coming to references, it only takes into account those sources which have been cited in the assignment.
• The main objective of adding a reference at the end of the document is to improve credence or support an idea or argument. As against, the bibliography is not used for supporting an argument.
• While reference is used in thesis and dissertation. On the other hand, bibliography is used in case of journal paper and research work.

To sum up, references and bibliography are almost same, but there are only subtle differences between the two, which lies in the items which are included in them. The primary use of references is to get recognition and authentication of the research work, whereas bibliography is appended with the aim of giving the reader the information on the sources relating to the topic.

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Amirjan Samim says

November 11, 2019 at 11:22 pm

All of the descriptions and information about the “reference and bibliography” and the difference between them are useful for the readers. Since both terms are closely related, this is why both terms are sometimes confusing for some people. Thanks for the helpful explanations you have given about the two terms mentioned above.

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March 25, 2021 at 5:23 pm

April 8, 2021 at 3:29 pm

Very helpful However I had a doubt regarding the placement of bibliography. Usually references are placed after the main body and conclusion. But where is bibliography placed?

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I had a doubt regarding the placement of bibliography. Usually references are placed after the main body and conclusion. But where is bibliography placed?

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Research Process: A Step-By-Step Guide: Citing and Referencing

• Getting Started
• Step 1: Developing a Topic
• Search Tips
• Scholarly vs. Popular Sources
• Primary and Secondary Sources
• Taking notes and Creating Outlines
• Academic Writing
• Citing and Referencing
• Harvard Referencing: Part 1
• Harvard Referencing: Part 2

What's the difference between citing and referencing ...?

When you start out with citing and referencing it's easy to get confused as to which is which:

• Cite = when you mark within your text to show that the the information comes from a published source
• Reference = when you give full publication details of the sources in an A-Z list by author surname at the end of your work
• Reference list = includes only those authorities that have been cited in the document

Quick introduction to plagiarism and referencing

Referencing

Why cite and reference?

• Validates  your work - by showing that your work is based on that of authorities in the field, you give credibility to and showcase the research you have done
• Maintains  academic integrity by giving credit to the original authors of the sources you have used
• Helps readers to locate  the sources you have consulted
• Situates  your work in the discipline  - you are building on work that has already been done in your field
• Avoids plagiarism

What is common knowledge?

You do not need to acknowledge a source for information that is common knowledge .

Common knowledge is information that either the general public or the average reader in your subject area would know. If you are unsure if something is common knowledge you should include a reference for it. 

Use DkIT's Quick guide to Harvard referencing

For detailed information with specific examples and a link to the full length version of DkIT's Guide to Harvard Referencing see:

Quick guide to Harvard referencing.

• << Previous: Plagiarism
• Next: Harvard Referencing: Part 1 >>
• Last Updated: Jan 24, 2024 1:48 PM
• URL: https://dkit.ie.libguides.com/researchprocess

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Chapter 13: Unobtrusive Research: Qualitative And Quantitative Approaches

Babbie, E. (2010). The practice of social research (12th ed.). Belmont, CA: Wadsworth.

Esterberg, K. G. (2002). Qualitative methods in social research . Boston, MA: McGraw-Hill.

Garfinkle, H. (1967). Studies in ethnomethodology. Englewood Cliffs, NJ: Prentice Hall.

Gubrium, J. F., & Holstein, J. A. (2000). Analyzing interpretative practice. In N. Denzin & Y.S. Lincoln (Eds.), The handbook of qualitative research (2nd ed.), (pp. 487-508). Thousand Oaks, CA: SAGE Publications.

Heritage, J. C. (1984). Garfinkel & ethnomethodology. Cambridge: UK. Polity Press.

Krippendorff, K. (2004a). Content analysis: An introduction to its methodology (2nd ed.). Thousand Oaks, CA: Sage.

Krippendorf, K. (2004b). Reliability in content analysis: Some common misconceptions and recommendations. Human Communication Research, 30 (3), 411-433. https://doi.org/10.1111/j.1468-2958.2004.tb00738.x

Lombard, M., Snyder-Duch, J., & Campenella Bracken, C. (2010). Practical resources for assessing and reporting intercoder reliability in content analysis research projects. Retrieved from http://matthewlombard.com/reliability/#How%20should%20researchers%20calculate%20intercoder%20reliability%20What%20software%20is%20available

Palys, T., & Atchison, C. (2014). Research decisions: Quantitative, qualitative, and mixed methods approaches (5th ed.) . Toronto, Canada: Nelson Education.

Patton, M. Q. (2015). Qualitative research & evaluation methods: Integrating theory and practice (4th ed.). Thousand Oaks, CA: SAGE Publications.

Saylor Academy. (2012). Principles of sociological inquiry: Qualitative and quantitative methods. Washington, DC: Saylor Academy. Retrieved from https://www.saylor.org/site/textbooks/Principles%20of%20Sociological%20Inquiry.pdf

Schutt, R. K. (2012). Investigating the social world: The process and practice of research. Thousand Oaks, CA: SAGE Publications.

Sheppard, V. A., & Fennell, D. A. (2019, August). Progress in public sector tourism policy: Toward an ethic for non-human animals. Tourism Management, 73 , 134-142. doi: https://doi.org/10.1016/j.tourman.2018.11.017

Research Methods for the Social Sciences: An Introduction Copyright © 2020 by Valerie Sheppard is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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Reference Examples

More than 100 reference examples and their corresponding in-text citations are presented in the seventh edition Publication Manual . Examples of the most common works that writers cite are provided on this page; additional examples are available in the Publication Manual .

To find the reference example you need, first select a category (e.g., periodicals) and then choose the appropriate type of work (e.g., journal article ) and follow the relevant example.

When selecting a category, use the webpages and websites category only when a work does not fit better within another category. For example, a report from a government website would use the reports category, whereas a page on a government website that is not a report or other work would use the webpages and websites category.

Also note that print and electronic references are largely the same. For example, to cite both print books and ebooks, use the books and reference works category and then choose the appropriate type of work (i.e., book ) and follow the relevant example (e.g., whole authored book ).

Examples on these pages illustrate the details of reference formats. We make every attempt to show examples that are in keeping with APA Style’s guiding principles of inclusivity and bias-free language. These examples are presented out of context only to demonstrate formatting issues (e.g., which elements to italicize, where punctuation is needed, placement of parentheses). References, including these examples, are not inherently endorsements for the ideas or content of the works themselves. An author may cite a work to support a statement or an idea, to critique that work, or for many other reasons. For more examples, see our sample papers .

Reference examples are covered in the seventh edition APA Style manuals in the Publication Manual Chapter 10 and the Concise Guide Chapter 10

Related handouts

• Common Reference Examples Guide (PDF, 147KB)
• Reference Quick Guide (PDF, 225KB)

Textual Works

Textual works are covered in Sections 10.1–10.8 of the Publication Manual . The most common categories and examples are presented here. For the reviews of other works category, see Section 10.7.

• Journal Article References
• Magazine Article References
• Newspaper Article References
• Blog Post and Blog Comment References
• UpToDate Article References
• Book/Ebook References
• Diagnostic Manual References
• Children’s Book or Other Illustrated Book References
• Classroom Course Pack Material References
• Religious Work References
• Chapter in an Edited Book/Ebook References
• Dictionary Entry References
• Wikipedia Entry References
• Report by a Government Agency References
• Report with Individual Authors References
• Brochure References
• Ethics Code References
• Fact Sheet References
• ISO Standard References
• Press Release References
• White Paper References
• Conference Presentation References
• Conference Proceeding References
• Published Dissertation or Thesis References
• Unpublished Dissertation or Thesis References
• ERIC Database References
• Preprint Article References

Data and Assessments

Data sets are covered in Section 10.9 of the Publication Manual . For the software and tests categories, see Sections 10.10 and 10.11.

• Data Set References
• Toolbox References

Audiovisual Media

Audiovisual media are covered in Sections 10.12–10.14 of the Publication Manual . The most common examples are presented together here. In the manual, these examples and more are separated into categories for audiovisual, audio, and visual media.

• Artwork References
• Clip Art or Stock Image References
• Film and Television References
• Musical Score References
• Online Course or MOOC References
• Podcast References
• PowerPoint Slide or Lecture Note References
• Radio Broadcast References
• TED Talk References
• Transcript of an Audiovisual Work References
• YouTube Video References

Online Media

Online media are covered in Sections 10.15 and 10.16 of the Publication Manual . Please note that blog posts are part of the periodicals category.

• Facebook References
• Instagram References
• LinkedIn References
• Online Forum (e.g., Reddit) References
• TikTok References
• X References
• Webpage on a Website References
• Clinical Practice References
• Open Educational Resource References
• Whole Website References

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Research Methodology and Identifying Key References Used

• First Online: 03 January 2018

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Case study completion should be seen merely as an interaction process, where many actions take place before the actual empirical data is gathered and analysed, and where previous research plays a key role. Systematic and well-planned data-gathering is at the heart of the process. It is illustrated here that case methodology references only change very slowly, if at all: two studies from the 1980s are still considered to be key methodological sources today. However, some new additions have appeared in the last two decades.

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Hilmola, OP. (2018). Research Methodology and Identifying Key References Used. In: Supply Chain Cases. Palgrave Pivot, Cham. https://doi.org/10.1007/978-3-319-71658-9_8

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1. introduction, 3. discussion, 4. conclusions, acknowledgments, funding information, author contributions, competing interests, data availability, scite: a smart citation index that displays the context of citations and classifies their intent using deep learning.

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Josh M. Nicholson , Milo Mordaunt , Patrice Lopez , Ashish Uppala , Domenic Rosati , Neves P. Rodrigues , Peter Grabitz , Sean C. Rife; scite: A smart citation index that displays the context of citations and classifies their intent using deep learning. Quantitative Science Studies 2021; 2 (3): 882–898. doi: https://doi.org/10.1162/qss_a_00146

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Citation indices are tools used by the academic community for research and research evaluation that aggregate scientific literature output and measure impact by collating citation counts. Citation indices help measure the interconnections between scientific papers but fall short because they fail to communicate contextual information about a citation. The use of citations in research evaluation without consideration of context can be problematic because a citation that presents contrasting evidence to a paper is treated the same as a citation that presents supporting evidence. To solve this problem, we have used machine learning, traditional document ingestion methods, and a network of researchers to develop a “smart citation index” called scite , which categorizes citations based on context. Scite shows how a citation was used by displaying the surrounding textual context from the citing paper and a classification from our deep learning model that indicates whether the statement provides supporting or contrasting evidence for a referenced work, or simply mentions it. Scite has been developed by analyzing over 25 million full-text scientific articles and currently has a database of more than 880 million classified citation statements. Here we describe how scite works and how it can be used to further research and research evaluation.

https://publons.com/publon/10.1162/qss_a_00146

Citations are a critical component of scientific publishing, linking research findings across time. The first citation index in science, created in 1960 by Eugene Garfield and the Institute for Scientific Information, aimed to “be a spur to many new scientific discoveries in the service of mankind” ( Garfield, 1959 ). Citation indices have facilitated the discovery and evaluation of scientific findings across all fields of research. Citation indices have also led to the establishment of new research fields, such as bibliometrics, scientometrics, and quantitative studies, which have been informative in better understanding science as an enterprise. From these fields have come a variety of citation-based metrics, such as the h -index, a measurement of researcher impact ( Hirsch, 2005 ); the Journal Impact Factor (JIF), a measurement of journal impact ( Garfield, 1955 , 1972 ); and the citation count, a measurement of article impact. Despite the widespread use of bibliometrics, there have been few improvements in citations and citation indices themselves. Such stagnation is partly because citations and publications are largely behind paywalls, making it exceedingly difficult and prohibitively expensive to introduce new innovations in citations or citation indices. This trend is changing, however, with open access publications becoming the standard ( Piwowar, Priem, & Orr, 2019 ) and organizations such as the Initiative for Open Citations ( Initiative for Open Citations, 2017 ; Peroni & Shotton, 2020 ) helping to make citations open. Additionally, with millions of documents being published each year, creating a citation index is a large-scale challenge involving significant financial and computational costs.

Historically, citation indices have only shown the connections between scientific papers without any further contextual information, such as why a citation was made. Because of the lack of context and limited metadata available beyond paper titles, authors, and the date of publications, it has only been possible to calculate how many times a work has been cited, not analyze broadly how it has been cited. This is problematic given citations’ central role in the evaluation of research. In short, not all citations are made equally, yet we have been limited to treating them as such.

Here we describe scite (scite.ai), a new citation index and tool that takes advantage of recent advances in artificial intelligence to produce “Smart Citations.” Smart Citations reveal how a scientific paper has been cited by providing the context of the citation and a classification system describing whether it provides supporting or contrasting evidence for the cited claim, or if it just mentions it.

Such enriched citation information is more informative than a traditional citation index. For example, when Viganó, von Schubert et al. (2018) cites Nicholson, Macedo et al. (2015) , traditional citation indices report this citation by displaying the title of the citing paper and other bibliographic information, such as the journal, year published, and other metadata. Traditional citation indices do not have the capacity to examine contextual information or how the citing paper used the citation, such as whether it was made to support or contrast the findings of the cited paper or if it was made in the introduction or the discussion section of the citing paper. Smart Citations display the same bibliographical information shown in traditional citation indices while providing additional contextual information, such as the citation statement (the sentence containing the in-text citation from the citing article), the citation context (the sentences before and after the citation statement), the location of the citation within the citing article (Introduction, Materials and Methods, Results, Discussion, etc.), the citation type indicating intent (supporting, contrasting, or mentioning), and editorial information from Crossref and PubMed, such as corrections and whether the article has been retracted ( Figure 1 ). Scite previously relied on Retraction Watch data but moved away from this due to licensing issues. Going forward, scite will use its own approach 1 to retraction detection, as well as data from Crossref and PubMed.

Example of scite report page. The scite report page shows citation context, citation type, and various features used to filter and organize this information, including the section where the citation appears in the citing paper, whether or not the citation is a self-citation, and the year of the publication. The example scite report shown in the figure can be accessed at the following link: https://scite.ai/reports/10.7554/elife.05068 .

Adding such information to citation indices has been proposed before. In 1964, Garfield described an “intelligent machine” to produce “citation markers,” such as “critique” or, jokingly, “calamity for mankind” ( Garfield, 1964 ). Citation types describing various uses of citations have been systematically described by Peroni and Shotton in CiTO, the Ci tation T yping O ntology ( Peroni & Shotton, 2012 ). Researchers have used these classifications or variations of them in several bibliometric studies, such as the analysis of citations ( Suelzer, Deal et al., 2019 ) made to the retracted Wakefield paper ( Wakefield, Murch et al., 1998 ), which found most citations to be negative in sentiment. Leung, Macdonald et al. (2017) analyzed the citations made to a five-sentence letter purporting to show opioids as nonaddictive ( Porter & Jick, 1980 ), finding that most citations were uncritically citing the work. Based on these findings, the journal appended a public health warning to the original letter. In addition to citation analyses at the individual article level, citation analyses taking into account the citation type have also been performed on subsets of articles or even entire fields of research. Greenberg (2009) discovered that citations were being distorted, for example being used selectively to exclude contradictory studies to create a false authority in a field of research, a practice carried into grant proposals. Selective citing might be malicious, as suggested in the Greenberg study, but it might also simply reflect sloppy citation practices or citing without reading. Indeed, Letrud and Hernes (2019) recently documented many cases where people were citing reports for the opposite conclusions than the original authors made.

Despite the advantages of citation types, citation classification and analysis require substantial manual effort on the part of researchers to perform even small-scale analyses ( Pride, Knoth, & Harag, 2019 ). Automating the classification of citation types would allow researchers to dramatically expand the scale of citation analyses, thereby allowing researchers to quickly assess large portions of scientific literature. PLOS Labs attempted to enhance citation analysis with the introduction of “rich citations,” which included various additional features to traditional citations such as retraction information and where the citation appeared in the citing paper ( PLOS, 2015 ). However, the project seemed to be mostly a proof of principle, and work on rich citations stopped in 2015, although it is unclear why. Possible reasons that the project did not mature reflect the challenges of accessing the literature at scale, finding a suitable business model for the application, and classifying citation types with the necessary precision and recall for it to be accepted by users. It is only recently that machine learning techniques have evolved to make this task possible, as we demonstrate here. Additional resources, such as the Colil Database ( Fujiwara & Yamamoto, 2015 ) and SciRide Finder ( Volanakis & Krawczyk, 2018 ) both allow users to see the citation context from open access articles indexed in PubMed Central. However, adoption seems to be low for both tools, presumably due to limited coverage of only open access articles. In addition to the development of such tools to augment citation analysis, various researchers have performed automated citation typing. Machine learning was used in early research to identify citation intent ( Teufel, Siddharthan, & Tidhar, 2006 ) and recently Cohan, Ammar et al. (2019) used deep learning techniques. Athar (2011) , Yousif, Niu et al. (2019) , and Yan, Chen, and Li (2020) also used machine learning to identify positive and negative sentiments associated with the citation contexts.

Here, by combining the largest citation type analysis performed to date and developing a useful user interface that takes advantage of the extra contextual information available, we introduce scite, a smart citation index.

2.1. Overview

The retrieval of scientific articles

The identification and matching of in-text citations and references within a scientific article

The matching of references against a bibliographic database

The classification of the citation statements into citation types using deep learning.

The scite ingestion process. Documents are retrieved from the internet, as well as being received through file transfers directly from publishers and other aggregators. They are then processed to identify citations, which are then tied to items in a paper’s reference list. Those citations are then verified, and the information is inserted into scite’s database.

We describe the four components in more detail below.

2.2. Retrieval of Scientific Documents

Access to full-text scientific articles is necessary to extract and classify citation statements and the citation context. We utilize open access repositories such as PubMed Central and a variety of open sources as identified by Unpaywall ( Else, 2018 ), such as open access publishers’ websites, university repositories, and preprint repositories, to analyze open access articles. Other relevant open access document sources, such as Crossref TDM and the Internet Archive have been and are continually evaluated as new sources for document ingestion. Subscription articles used in our analyses have been made available through indexing agreements with over a dozen publishers, including Wiley, BMJ, Karger, Sage, Europe PMC, Thieme, Cambridge University Press, Rockefeller University Press, IOP, Microbiology Society, Frontiers, and other smaller publishers. Once a source of publications is established, documents are retrieved on a regular basis as new articles become available to keep the citation record fresh. Depending on the source, documents may be retrieved and processed anywhere between daily and monthly.

2.3. Identification of In-Text Citations and References from PDF and XML Documents

A large majority of scientific articles are only available as PDF files 2 , a format designed for visual layout and printing, not text-mining. To match and extract citation statements from PDFs with high fidelity, an automated process for converting PDF files into reliable structured content is required. Such conversion is challenging, as it requires identifying in-text citations (the numerical or textual callouts that refer to a particular item in the reference list), identifying and parsing the full bibliographical references in the reference list, linking in-text citations to the correct items in this list, and linking these items to their digital object identifiers (DOIs) in a bibliographic database. As our goal is to eventually process all scientific documents, this process must be scalable and affordable. To accomplish this, we utilize GROBID, an open-source PDF-to-XML converter tool for scientific literature ( Lopez, 2020a ). The goal of GROBID is to automatically convert scholarly PDFs into structured XML representations suitable for large-scale analysis. The structuration process is realized by a cascade of supervised machine learning models. The tool is highly scalable (around five PDF documents per second on a four-core server), is robust, and includes a production-level web API, a Docker image, and benchmarking facilities. GROBID is used by many large scientific information service providers, such as ResearchGate, CERN, and the Internet Archive to support their ingestion and document workflows ( Lopez, 2020a ). The tool is also used for creating machine-friendly data sets of research papers, for instance, the recent CORD-19 data set ( Wang, Lo et al., 2020 ).

Particularly relevant to scite, GROBID was benchmarked as the best open source bibliographical references parser by Tkaczyk, Collins et al. (2018) and has a relatively unique focus on citation context extraction at scale, as illustrated by its usage for building the large-scale Semantic Scholar Open Research Corpus (S2ORC), a corpus of 380.5 million citations, including citation mentions excerpts from the full-text body ( Lo, Wang et al., 2020 ).

In addition to PDFs, some scientific articles are available as XML files, such as the Journal Article Tag Suite (JATS) format. Formatting articles in PDF and XML has become standard practice for most mainstream publishers. While structured XML can solve many issues that need to be addressed with PDFs, XML full texts appear in a variety of different native publisher XML formats, often incomplete and inconsistent from one to another, loosely constrained, and evolving over time into specific versions.

To standardize the variety of XML formats we receive into a common format, we rely upon the open-source tool Pub2TEI ( Lopez, 2020b ). Pub2TEI converts various XML styles from publishers to the same standard TEI format as the one produced by GROBID. This centralizes our document processing across PDF and XML sources.

2.4. Matching References Against the Bibliographic Database Crossref

Once we have identified and matched the in-text citation to an item in a paper’s reference list, this information must be validated. We use an open-source tool, biblio-glutton ( Lopez, 2020c ), which takes a raw bibliographical reference, as well as optionally parsed fields (title, author names, etc.) and matches it against the Crossref database—widely regarded as the industry standard source of ground truth for scholarly publications 3 . The matching accuracy of a raw citation reaches an F-score of 95.4 on a set of 17,015 raw references associated with a DOI, extracted from a data set of 1,943 PMC articles 4 compiled by Constantin (2014) . In an end-to-end perspective, still based on an evaluation with the corpus of 1,943 PMC articles, combining GROBID PDF extraction of citations and bibliographical references with biblio-glutton validations, the pipeline successfully associates around 70% of citation contexts to cited papers with correctly identified DOIs in a given PDF file. When the full-text XML version of an article is available from a publisher, references and linked citation contexts are normally correctly encoded, and the proportion of fully solved citation contexts corresponding to the proportion of cited paper with correctly identified DOIs is around 95% for PMC XML JATS files. The scite platform today only ingests publications with a DOI and only matches references against bibliographical objects with a registered DOI. The given evaluation figures have been calculated relative to these types of citations.

2.5. Task Modeling and Training Data

Extracted citation statements are classified into supporting, contrasting, or mentioning, to identify studies that have tested the claim and to evaluate how a scientific claim has been evaluated in the literature by subsequent research.

We emphasize that scite is not doing sentiment analysis. In natural language processing, sentiment analysis is the study of affective and subjective statements. The most common affective state considered in sentiment analysis is a mere polar view from positive sentiment to negative sentiment, which appeared to be particularly useful in business applications (e.g., product reviews and movie reviews). Following this approach, a subjective polarity can be associated with a citation to try to capture an opinion about the cited paper. The evidence used for sentiment classification relies on the presence of affective words in the citation context, with an associated polarity score capturing the strength of the affective state ( Athar, 2014 ; Halevi & Schimming, 2018 ; Hassan, Imran et al., 2018 ; Yousif et al., 2019 ). Yan et al. (2020) , for instance, use a generic method called SenticNet to identify sentiments in citation contexts extracted from PubMed Central XML files, without particular customization to the scientific domain (only a preprocessing to remove the technical terms from the citation contexts is applied). SenticNet uses a polarity measure associated with 200,000 natural language concepts, propagated to the words and multiword terms realizing these concepts.

In contrast, scite focuses on the authors’ reasons for citing a paper. We use a discrete classification into three discursive functions relative to the scientific debate; see Murray, Lamers et al. (2019) for an example of previous work with typing citations based on rhetorical intention. We consider that for capturing the reliability of a claim, a classification decision into supporting or contrasting must be backed by scientific arguments. The evidence involved in our assessment of citation intent is directed to the factual information presented in the citation context, usually statements about experimental facts and reproducibility results or presentation of a theoretical argument against or agreeing with the cited paper.

Examples of supporting, contrasting, and mentioning citation statements are given in Table 1 , with explanations describing why they are classified as such, including examples where researchers have expressed confusion or disagreement with our classification.

Real-world examples of citation statement classifications with examples explaining why a citation type has or has not been assigned. Citation classifications are based on the following two requirements: there needs to be a written indication that the statement supports or contrasts the cited paper; and there needs to be an indication that it provides evidence for this assertion.

Importantly, just as it is critical to optimize for accuracy of our deep learning model when classifying citations, it is equally important to make sure that the right terminology is used and understood by researchers. We have undergone multiple iterations of the design and display of citation statements and even the words used to define our citation types, including using previous words such as refuting and disputing to describe contrasting citations and confirming to describe supporting citations. The reasons for these changes reflect user feedback expressing confusion over certain terms as well as our intent to limit any potentially inflammatory interpretations. Indeed, our aim with introducing these citation types is to highlight differences in research findings based on evidence, not opinion. The main challenge of this classification task is the highly imbalanced distribution of the three classes. Based on manual annotations of different publication domains and sources, we estimate the average distribution of citation statements as 92.6% mentioning, 6.5% supporting, and 0.8% contrasting statements. Obviously, the less frequent the class, the more valuable it is. Most of the efforts in the development of our automatic classification system have been directed to address this imbalanced distribution. This task has required first the creation of original training data by experts—scientists with experience in reading and interpreting scholarly papers. Focusing on data quality, the expert classification was realized by multiple-blind manual annotation (at least two annotators working in parallel on the same citation), followed by a reconciliation step where the disagreements were further discussed and analyzed by the annotators. To keep track of the progress of our automatic classification over time, we created a holdout set of 9,708 classified citation records. To maintain a class distribution as close as possible to the actual distribution in current scholarly publications, we extracted the citation contexts from Open Access PDF of Unpaywall by random sampling with a maximum of one context per document.

We separately developed a working set where we tried to oversample the two less frequent classes (supporting, contrasting) with the objective of addressing the difficulties implied by the imbalanced automatic classification. We exploited the classification scores of our existing classifiers to select more likely supporting and contrasting statements for manual classification. At the present time, this set contains 38,925 classified citation records. The automatic classification system was trained with this working set, and continuously evaluated with the immutable holdout set to avoid as much bias as possible. An n -fold cross-evaluation on the working set, for instance, would have been misleading because the distribution of the classes in this set was artificially modified to boost the classification accuracy of the less frequent classes.

Before reconciliation, the observed average interannotator agreement percentage was 78.5% in the open domain and close to 90% for batches in biomedicine. It is unclear what accounts for the difference. Reconciliation, further completed with expert review by core team members, resulted in highly consensual classification decisions, which contrast with typical multiround disagreement rates observed with sentiment classification. Athar (2014) , for instance, reports Cohen’s k annotator agreement of 0.675 and Ciancarini, Di Iorio et al. (2014) report k = 0.13 and k = 0.15 for the property groups covering confirm / supports and critiques citation classification labels. A custom open source document annotation web application, docanno ( Nakayama, Kubo et al., 2018 ) was deployed to support the first round of annotations.

Overall, the creation of our current training and evaluation holdout data sets has been a major 2-year effort involving up to eight expert annotators and nearly 50,000 classified citation records. In addition to the class, each record includes the citation sentence, the full “snippet” (citation sentence plus previous and next sentences), the source and target DOI, the reference callout string, and the hierarchical list of section titles where the citation occurs.

2.6. Machine Learning Classifiers

Improving the classification architecture: After initial experiments with RNN (Recursive Neural Network) architectures such as BidGRU (Bidirectional Gated Recurrent Unit, an architecture similar to the approach of Cohan et al. (2019) for citation intent classification), we obtained significant improvements with the more recently introduced ELMo (Embeddings from Language Models) dynamic embeddings ( Peters, Neumann et al., 2018 ) and an ensemble approach. Although the first experiments with BERT (Bidirectional Encoder Representations from Transformers) ( Devlin, Chang et al., 2019 ), a breakthrough architecture for NLP, were disappointing, fine-tuning SciBERT (a science-pretrained base BERT model) ( Beltagy, Lo, & Cohan, 2019 ) led to the best results and is the current production architecture of the platform.

Using oversampling and class weighting techniques: It is known that the techniques developed to address imbalanced classification in traditional machine learning can be applied successfully to deep learning too ( Johnson & Khoshgoftaar, 2019 ). We introduced in our system oversampling of less frequent classes, class weighting, and metaclassification with three binary classifiers. These techniques provide some improvements, but they rely on empirical parameters that must be re-evaluated as the training data changes.

Extending the training data for less frequent classes: As mentioned previously, we use an active learning approach to select the likely less frequent citation classes based on the scores of the existing classifiers. By focusing on edge cases over months of manual annotations, we observed significant improvements in performance for predicting contrasting and supporting cases.

Progress on classification results over approximately 1 year, evaluated on a fixed holdout set of 9,708 examples. In parallel with these various iterations on the classification algorithms, the training data was raised from 30,665 (initial evaluation with BidGRU) to 38,925 examples (last evaluation with SciBERT) via an active learning approach.

Accuracy of SciBERT classifier, currently deployed on the scite platform, evaluated on a holdout set of 9,708 examples.

Note: When deploying classification models in production, we balance the precision/recall so that all the classes have a precision higher than 80%.

Given the unique nature of scite, there are a number of additional considerations. First, scaling is a key requirement of scite, which addresses the full corpus of scientific literature. While providing good results, the prediction with the ELMo approach is 20 times slower than with SciBERT, making it less attractive for our platform. Second, we have experimented with using section titles to improve classifications—for example, one might expect to find supporting and contrasting statements more often in the Results section of a paper and mentioning statements in the Introduction. Counterintuitively, including section titles in our model had no impact on F -scores, although it did slightly improve precision. It is unclear why including section titles failed to improve F -scores. However, it might relate to the challenge of correctly identifying and normalizing section titles from documents. Third, segmenting scientific text into sentences presents unique challenges due to the prevalence of abbreviations, nomenclatures, and mathematical equations. Finally, we experimented with various context windows (i.e., the amount of text used in the classification of a citation) but were only able to improve the F -score for the contrasting category by eight points by manually selecting the most relevant phrases in the context window. Automating this process might improve classifications, but doing so presents a significant technical challenge. Other possible improvements of the classifier include multitask training, refinement of classes, increase of training data via improved active learning techniques, and integration of categorical features in the transformer classifier architecture.

We believe that the specificity of our evidence-based citation classes, the size and the focus on the quality of our manually annotated data set (multiple rounds of blind annotations with final collective reconciliation), the customization and continuous improvement of a state of the art deep learning classifier, and finally the scale of our citation analysis distinguishes our work from existing developments in automatic citation analysis.

2.7. Citation Statement and Classification Pipeline

TEI XML data is parsed in Python using the BeautifulSoup library and further segmented into sentences using a combination of spaCy ( Honnibal, Montani et al., 2018 ) and Natural Language Toolkit’s Punkt Sentence Tokenizer ( Bird, Klein, & Loper, 2009 ). These sentence segmentation candidates are then postprocessed with custom rules to better fit scientific texts, existing text structures, and inline markups. For instance, a sentence split is forbidden inside a reference callout, around common abbreviations not supported by the general-purpose sentence segmenters, or if it is conflicting with a list item, paragraph, or section break.

The implementation of the classifier is realized by a component we have named Veracity , which provides a custom set of deep learning classifiers built on top of the open source DeLFT library ( Lopez, 2020d ). Veracity is written in Python and employs Keras and TensorFlow for text classification. It runs on a single server with an NVIDIA GP102 (GeForce GTX 1080 Ti) graphics card with 3,584 CUDA cores. This single machine is capable of classifying all citation statements as they are processed. Veracity retrieves batches of text from the scite database that have yet to be classified, processes them, and updates the database with the results. When deploying classification models in production, we balance the precision/recall so that all the classes have a precision higher than 80%. For this purpose, we use the holdout data set to adjust the class weights at the prediction level. After evaluation, we can exploit all available labeled data to maximize the quality, and the holdout set captures a real-world distribution adapted to this final tuning.

2.8. User Interface

The resulting classified citations are stored and made available on the scite platform. Data from scite can be accessed in a number of ways (downloads of citations to a particular paper; the scite API, etc.). However, users will most commonly access scite through its web interface. Scite provides a number of core features, detailed below.

The scite report page ( Figure 1 ) displays summary information about a given paper. All citations in the scite database to the paper are displayed, and users can filter results by classification (supporting, mentioning, contrasting), paper section (e.g., Introduction, Results), and the type of citing article (e.g., preprint, book, etc.). Users can also search for text within citation statements and surrounding citation context. For example, if a user wishes to examine how an article has been cited with respect to a given concept (e.g., fear), they can search for citation contexts that contain that key term. Each citation statement is accompanied by a classification label, as well as an indication of how confident the model is of said classification. For example, a citation statement may be classified as supporting with 90% confidence, meaning that the model is 90% certain that the statement supports the target citation. Finally, each citation statement can be flagged by individual users as incorrect, so that users can report a classification as incorrect, as well as justify their objection. After a citation statement has been flagged as incorrect, it will be reviewed and verified by two independent reviewers, and, if both agree, the recommended change will be implemented. In this way, scite supplements machine learning with human interventions to ensure that citations are accurately classified. This is an important feature of scite that allows researchers to interact with the automated citation types, correcting classifications that might otherwise be difficult for a machine to classify. It also opens the possibility for authors and readers to add more nuance to citation typing by allowing them to annotate snippets.

To improve the utility and usability of the smart citation data, scite offers a wide variety of tools common to other citation platforms, such as Scopus and Web of Science and other information retrieval software. These include literature searching functionality for researchers to find supported and contrasted research, visualizations to see research in context, reference checking for automatically evaluating references with scite’s data on an uploaded manuscript and more. Scite also offers plugins for popular web browsers and reference management software (e.g., Zotero) that allow easy access to scite reports and data in native research environments.

3.1. Research Applications

A number of researchers have already made use of scite for quantitative assessments of the literature. For example, Bordignon (2020) examined self-correction in the scientific record and operationalized “negative” citations as those that scite classified as contrasting. They found that negative citations are rare, even among works that have been retracted. In another example from our own group, Nicholson et al. (2020) examined scientific papers cited in Wikipedia articles and found that—like the scientific literature as a whole—the vast majority presented findings that have not been subsequently verified. Similar analyses could also be applied to articles in the popular press.

One can imagine a number of additional metascientific applications. For example, network analyses with directed graphs, valenced edges (by type of citation—supporting, contrasting, and mentioning), and individual papers as nodes could aid in understanding how various fields and subfields are related. A simplified form of this analysis is already implemented on the scite website (see Figure 3 ), but more complicated analyses that assess traditional network indices, such as centrality and clustering, could be easily implemented using standard software libraries and exports of data using the scite API.

A citation network representation using the scite Visualization tool. The nodes represent individual papers, with the edges representing supporting (green) or contrasting (blue) citation statements. The graph is interactive and can be expanded and modified for other layouts. The interactive visualization can be accessed at the following link: https://scite.ai/visualizations/global-analysis-of-genome-transcriptome-9L4dJr?dois%5B0%5D=10.1038%2Fmsb.2012.40&dois%5B1%5D=10.7554%2Felife.05068&focusedElement=10.7554%2Felife.05068 .

3.2. Implications for Scholarly Publishers

There are a number of implications for scholarly publishers. At a very basic level, this is evident in the features that scite provides that are of particular use to publishers. For example, the scite Reference Check parses the reference list of an uploaded document and produces a report indicating how items in the list have been cited, flagging those that have been retracted or have otherwise been the subject of editorial concern. This type of screening can help publishers and editors ensure that articles appearing in their journals do not inadvertently cite discredited works. Evidence in scite’s own database indicates that this would solve a seemingly significant problem, as in 2019 alone nearly 6,000 published papers cited works that had been retracted prior to 2019. Given that over 95% of citations made to retracted articles are in error ( Schneider, Ye et al., 2020 ), had the Reference Check tool been applied to these papers during the review process, the majority of these mistakes could have been caught.

However, there are additional implications for scholarly publishing that go beyond the features provided by scite. We believe that by providing insights into how articles are cited—rather than simply noting that the citation has occurred—scite can alter the way in which journals, institutions, and publishers are assessed. Scite provides journals and institutions with dashboards that indicate the extent to which papers with which they are associated have been supported or contrasted by subsequent research ( Figure 4 ). Even without reliance on specific metrics, the approach that scite provides prompts the question: What if we normalized the assessment of journals, institutions and researchers in terms of how they were cited rather than the simple fact that they were cited alone?

A scite Journal Dashboard showing the aggregate citation information at the journal level, including editorial notices and the scite Index, a journal metric that shows the ratio of supporting citations over supporting plus contrasting citations. Access to the journal dashboard in the figure and other journal dashboards is available here: https://scite.ai/journals/0138-9130 .

3.3. Implications for Researchers

Given the fact that nearly 3 million scientific papers are published every year ( Ware & Mabe, 2015 ), researchers increasingly report feeling overwhelmed by the amount of literature they must sift through as part of their regular workflow ( Landhuis, 2016 ). Scite can help by assisting researchers in identifying relevant, reliable work that is narrowly tailored to their interests, as well as better understanding how a given paper fits into the broader context of the scientific literature. For example, one common technique for orienting oneself to new literature is to seek out the most highly cited papers in that area. If the context of those citations is also visible, the value of a given paper can be more completely assessed and understood. There are, however, additional—although perhaps less obvious—implications. If citation types are easily visible, it is possible that researchers will be incentivized to make replication attempts easier (for example, by providing more explicit descriptions of methods or instruments) in the hope that their work will be replicated.

3.4. Limitations

At present, the biggest limitation for researchers using scite is the size of the database. At the time of this writing, scite has ingested over 880 million separate citation statements from over 25 million scholarly publications. However, there are over 70 million scientific publications in existence ( Ware & Mabe, 2015 ); scite is constantly ingesting new papers from established sources and signing new licensing agreements with publishers, so this limitation should abate over time. However, given that the ingestion pipeline fails to identify approximately 30% of citation statements/references in PDF files (~5% in XML), the platform will necessarily contain fewer references than services such as Google Scholar and Web of Science, which do not rely on ingesting the full text of papers. Even if references are reliably extracted and matched with a DOI or directly provided by publishers, a reference is currently only visible on the scite platform if it is matched with at least one citation context in the body of the article. As such, the data provided by scite will necessarily miss a measurable percentage of citations to a given paper. We are working to address these limitations in two ways: First, we are working toward ingesting more full-text XML and improving our ability to detect document structure in PDFs. Second, we have recently supplemented our Smart Citation data with “traditional” citation metadata provided by Crossref (see “Without Citation Statements” shown in Figure 1 ), which surfaces references that we would otherwise miss. Indeed, this Crossref data now includes references from publishers with previously closed references such as Elsevier and the American Chemical Society. These traditional citations can later be augmented to include citation contexts as we gain access to full text.

Another limitation is related to the classification of citations. First, as noted previously, the Veracity software does not perfectly classify citations. This can partly be explained by the fact that language in the (biomedical) sciences is little standardized (unlike law, where shepardizing is a standing term describing the “process of using a citator to discover the history of a case or statute to determine whether it is still good law”; see Lehman & Phelps, 2005 ). However, the accuracy of the classifier will likely increase over time as technology improves and the training data set increases in size. Second, the ontology currently employed by scite (supporting, mentioning, and contrasting) necessarily misses some nuance regarding how references are cited in scientific papers. One key example relates to what “counts” as a contrasting citation: At present, this category is limited to instances where new evidence is presented (e.g., a failed replication attempt or a difference in findings). However, it might also be appropriate to include conceptual and logical arguments against a given paper in this category. Moreover, in our system, the evidence behind the supporting or contrasting citation statements is not being assessed; thus a supporting citation statement might come from a paper where the experimental evidence is weak and vice versa. We do display the citation tallies that papers have received so that users can assess this but it would be exceedingly difficult to also classify the sample size, statistics, and other parameters that define how robust a finding is.

The automated extraction and analysis of scientific citations is a technically challenging task, but one whose time has come. By surfacing the context of citations rather than relying on their mere existence as an indication of a paper’s importance and impact, scite provides a novel approach to addressing pressing questions for the scientific community, including incentivizing replicable works, assessing an increasingly large body of literature, and quantitatively studying entire scientific fields.

We would like to thank Yuri Lazebnik for his help in conceptualizing and building scite.

This work was supported by NIDA grant 4R44DA050155-02.

Josh M. Nicholson: Conceptualization, Data acquisition, Analysis and interpretation of data, Writing—original draft, Writing—Review and editing. Milo Mordaunt: Data acquisition, Analysis and interpretation of data. Patrice Lopez: Conceptualization, Analysis and interpretation of data, Writing—original draft, Writing—Review and editing. Ashish Uppala: Analysis and interpretation of data, Writing—original draft, Writing—Review and editing. Domenic Rosati: Analysis and interpretation of data, Writing—original draft, Writing—Review and editing. Neves P. Rodrigues: Conceptualization. Sean C. Rife: Conceptualization, Data acquisition, Analysis and interpretation of data, Writing—original draft, Writing—Review and editing. Peter Grabitz: Conceptualization, Data acquisition, Analysis and interpretation of data, Writing—original draft, Writing—Review and editing.

The authors are shareholders and/or consultants or employees of Scite Inc.

Code used in the ingestion of manuscripts is available at https://github.com/kermitt2/grobid , https://github.com/kermitt2/biblio-glutton , and https://github.com/kermitt2/Pub2TEI . The classification of citation statements is performed by a modified version of DeLFT ( https://github.com/kermitt2/delft ). The training data used by the scite classifier is proprietary and not publicly available. The 880+ million citation statements are available at scite.ai but cannot be shared in full due to licensing arrangements made with publishers.

Details of how retractions and other editorial notices can be detected through an automated examination of metadata—even when there is no explicit indication that such notice(s) exist—will be made public via a manuscript currently in preparation.

As an illustration, the ISTEX project has been an effort from the French state leading to the purchase of 23 million full text articles from the mainstream publishers (Elsevier, Springer-Nature, Wiley, etc.) mainly published before 2005, corresponding to an investment of €55 million in acquisitions. The delivery of full text XML when available was a contractual requirement, but an XML format with structured body could be delivered by publishers for only around 10% of the publications.

For more information on the history and prevalence of Crossref, see https://www.crossref.org/about/ .

The evaluation data and scripts are available on the project GitHub repository; see biblio-glutton ( Lopez, 2020c ).

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Why Should the FDA Focus on Pragmatic Clinical Research?

• 1 US Food and Drug Administration, White Oak Campus, Silver Spring, Maryland
• Editor's Note Integrating Clinical Trials and Practice Gregory Curfman, MD JAMA
• Special Communication The Integration of Clinical Trials With the Practice of Medicine Derek C. Angus, MD, MPH; Alison J. Huang, MD, MAS; Roger J. Lewis, MD, PhD; Amy P. Abernethy, MD, PhD; Robert M. Califf, MD; Martin Landray, PhD; Nancy Kass, ScD; Kirsten Bibbins-Domingo, PhD, MD, MAS; JAMA Summit on Clinical Trials Participants; Ali B Abbasi; Kaleab Z Abebe; Amy P Abernethy; Stacey J. Adam; Derek C Angus; Jamy Ard; Rachel A Bender Ignacio ; Scott M Berry; Deepak L. Bhatt; Kirsten Bibbins-Domingo; Robert O. Bonow; Marc Bonten; Sharon A. Brangman; John Brownstein; Melinda J. B. Buntin; Atul J Butte; Robert M. Califf; Marion K Campbell; Anne R. Cappola; Anne C Chiang; Deborah Cook; Steven R Cummings; Gregory Curfman; Laura J Esserman; Lee A Fleisher; Joseph B Franklin; Ralph Gonzalez; Cynthia I Grossman; Tufia C. Haddad; Roy S. Herbst; Adrian F. Hernandez; Diane P Holder; Leora Horn; Grant D. Huang; Alison Huang; Nancy Kass; Rohan Khera; Walter J. Koroshetz; Harlan M. Krumholz; Martin Landray; Roger J. Lewis; Tracy A Lieu; Preeti N. Malani; Christa Lese Martin; Mark McClellan; Mary M. McDermott; Stephanie R. Morain; Susan A Murphy; Stuart G Nicholls; Stephen J Nicholls; Peter J. O'Dwyer; Bhakti K Patel; Eric Peterson; Sheila A. Prindiville; Joseph S. Ross; Kathryn M Rowan; Gordon Rubenfeld; Christopher W. Seymour; Rod S Taylor; Joanne Waldstreicher; Tracy Y. Wang JAMA

Traditional randomized clinical trials (RCTs) have long been a key tool underpinning drug and device development. The use of individual participant randomization and active or placebo controls in RCTs, combined with comprehensive collection of highly structured data, supports assay sensitivity. At the same time, focused enrollment criteria and careful attention to the collection of adverse events for specified follow-up periods promote detection of toxicities and risks. These trials support a system, regulated by the US Food and Drug Administration (FDA) and other global regulators, that allows the majority of candidate therapies whose risks outweigh benefits for intended use to be screened out while enabling safe and effective medical products to advance to market. However, the next stage—after product development and marketing authorization are completed and a therapy is integrated into clinical practice—needs serious attention.

• Editor's Note Integrating Clinical Trials and Practice JAMA

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Abbasi AB , Curtis LH , Califf RM. Why Should the FDA Focus on Pragmatic Clinical Research? JAMA. Published online June 03, 2024. doi:10.1001/jama.2024.6227

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• Published: 28 February 2024

Prevalence of loneliness and associations with health behaviours and body mass index in 5835 people living with and beyond cancer: a cross-sectional study

• Susan Smith 1 ,
• Phillippa Lally 2 ,
• Andrew Steptoe 1 ,
• Yanaina Chavez-Ugalde 3 ,
• Rebecca J Beeken 4   na1 &
• Abi Fisher 1   na1  

BMC Public Health volume  24 , Article number:  635 ( 2024 ) Cite this article

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A cancer diagnosis and its treatment may be an especially isolating experience. Despite evidence that positive health behaviours can improve outcomes for people living with and beyond cancer (LWBC), no studies have examined associations between loneliness and different health behaviours in this population. This study aimed to describe the prevalence of loneliness in a large sample of UK adults LWBC and to explore whether loneliness was associated with multiple health behaviours.

Participants were adults (aged  ≥  18 years) diagnosed with breast, prostate or colorectal cancer who completed the Health and Lifestyle After Cancer Survey. Loneliness was reported using the UCLA loneliness score, dichotomised into higher ( ≥  6) versus lower (< 6) loneliness. Engagement in moderate-to-vigorous physical activity, dietary intake, smoking status, alcohol use, and self-reported height and weight were recorded. Behaviours were coded to reflect meeting or not meeting the World Cancer Research Fund recommendations for people LWBC. Logistic regression analyses explored associations between loneliness and health behaviours. Covariates were age, sex, ethnicity, education, marital status, living situation, cancer type, spread and treatment, time since treatment, time since diagnosis and number of comorbid conditions. Multiple imputation was used to account for missing data.

5835 participants, mean age 67.4 (standard deviation = 11.8) years, completed the survey. 56% were female ( n  = 3266) and 44% ( n  = 2553) male, and 48% ( n  = 2786) were living with or beyond breast cancer, 32% ( n  = 1839) prostate, and 21% ( n  = 1210) colorectal. Of 5485 who completed the loneliness scale, 81% ( n  = 4423) of participants reported lower and 19% ( n  = 1035) higher loneliness. After adjustment for confounders, those reporting higher levels of loneliness had lower odds of meeting the WCRF recommendations for moderate-to-vigorous physical activity (Odds Ratio [OR] 0.78, 95% Confidence Internal [CI], 0.67, 0.97, p  =.028), fruit and vegetable intake (OR 0.81, CI 0.67, 1.00, p  =.046), and smoking (OR 0.62, 0.46, 0.84, p  =.003). No association was observed between loneliness and the other dietary behaviours, alcohol, or body mass index.

Conclusions

Loneliness is relatively common in people LWBC and may represent an unmet need. People LWBC who experience higher levels of loneliness may need additional support to improve their health behaviours.

Peer Review reports

There are over 3 million people living with and beyond a cancer diagnosis (LWBC) in the United Kingdom (UK) [ 1 ]. Assuming trends continue, this will increase by 1 million per decade to 2040 [ 2 ]. Similar increases have been observed in other developed countries [ 3 ]. As cancer survival rates continue to improve, it is crucial to ensure that people LWBC are supported to achieve the best quality of life, a key aim of cancer strategies [ 4 , 5 ]. Loneliness (the subjective negative experience of social isolation [ 6 , 7 ]) is an established risk factor for poorer health and higher mortality in the general population [ 8 , 9 , 10 , 11 ], and there is some indication that loneliness may result in worse outcomes after a cancer diagnosis [ 12 ].

In a meta-analysis of 87 prospective cohorts of cancer patients, factors associated with lower loneliness, such as greater social network size, higher perceived social support, and being married, were associated with 12–25% lower mortality, although a measure of loneliness itself was not included [ 13 ]. Furthermore, a synthesis of 20 qualitative studies identified sources of loneliness specifically related to a cancer diagnosis and treatments, including feeling alone in the experience, others’ avoidance of discussion about cancer, lack of understanding/misperceptions of cancer, lack of recognition of the impact of the side effects of treatment, and unmet needs in the healthcare system [ 14 ]. For instance, Rosedale described how women diagnosed with breast cancer reported that their healthy peers had difficulty grasping the magnitude of the challenges they faced. They described feeling left behind as others continued with their lives, resulting in feelings of loneliness, disconnectedness, and distress [ 15 ]. A meta-analysis of 15 observational studies describing the prevalence of loneliness after a cancer diagnosis found moderate prevalence and associations with a number of demographic and clinical factors [ 16 ]. However, the samples within the included studies were small (13/15 included  ≤  200 participants), and larger studies exploring loneliness after acute cancer treatment phases are needed.

Loneliness may impact health outcomes via both direct biological mechanisms and behavioural mechanisms [ 17 , 18 ]. For example, loneliness may have a negative impact on health behaviours in people LWBC and an ever-growing body of evidence suggests that healthier behaviours lead to better outcomes after a cancer diagnosis [ 19 , 20 , 21 , 22 ]. This has led a number of governing bodies, such as the World Cancer Research Fund and American Institute for Cancer Research (WCRF/AICR), to issue health behaviour guidance for those LWBC [ 23 , 24 ]. There is already evidence to suggest that some health behaviours worsen following a diagnosis of cancer and its treatments (e.g., decline in physical activity [ 25 , 26 ]), so negative effects could be exacerbated in lonelier people. However, data exploring associations between loneliness and health behaviours are mainly from the general population. A systematic review of 37 studies exploring the association between loneliness and physical activity, including healthy older adults and adolescents, found negative associations between physical activity and loneliness in 12 cross-sectional studies and one longitudinal study [ 27 ]. Although relationships are likely to be bidirectional, four prospective studies have found that people with higher levels of loneliness at baseline were less likely to be physically active at follow-up [ 28 , 29 , 30 , 31 ]. While Newall and colleagues reported that loneliness predicted perceived engagement in physical activity in a sample of 228 older adults, they also found that this relationship was moderated by happiness, suggesting that happiness may buffer against the negative effect of loneliness in this age group [ 29 ]. In a study of older adults taking part in the English Longitudinal Study of Ageing (ELSA), Kobayashi and Steptoe investigated the associations between social isolation and loneliness at baseline and engagement in health behaviours over 10 years [ 32 ]. After dichotomisation of health behaviours into meeting or failing to meet the public health recommendations, they observed that higher loneliness was associated with lower odds of meeting the recommendations for physical activity, smoking and body mass index (BMI), although the association between loneliness and health behaviours was lost after adjustment for sociodemographic variables [ 32 , 33 ]. Similarly, where Schrempf and colleagues examined how objective physical activity differs according to levels of social isolation and loneliness in ELSA, a negative association was observed between total physical activity counts and loneliness, although this was attenuated after adjusting for covariates [ 33 ]. Data exploring associations between loneliness and physical activity in people LWBC are lacking. In older breast cancer survivors, one prospective study found an inverse association between loneliness and physical activity over a five-year follow-up period [ 34 ], while another cross-sectional study found that lower social support and living alone was associated with lower levels of physical activity [ 35 ].

In addition to physical activity, there is also some evidence that loneliness can also impact health via smoking and poor dietary intake. A systematic review of studies on loneliness and smoking reported that over half of the 23 included studies observed an association between smoking and loneliness, and their results consistently demonstrated that lonely people were more likely to be smokers [ 36 ]. This association is likely to be bidirectional whereby smokers are also more likely to be lonely [ 37 ]. Despite qualitative data suggesting that experiencing loneliness may negatively impact eating habits in older adults [ 38 , 39 ], quantitative data exploring associations between loneliness and intake of different dietary components are lacking. Lastly, loneliness may impact body mass index (BMI) in people LWBC, as evidence from the general population suggests a complex association between loneliness and obesity due to factors such as weight-related stigma [ 40 , 41 ]. While there is conflicting evidence suggesting a BMI in the overweight range (25-29.9) may be associated with improved survival across some cancer types, explanations for this paradox have still yet to be established [ 42 , 43 ]. Acknowledging that this evidence is still inadequate to make specific recommendations with confidence, the WCRF recommends that people LWBC follow the guidelines published for healthy populations in maintaining a BMI in the healthy range (18.5–24.9), recognising that this is unlikely to be harmful to people LWBC who have completed treatment [ 42 ].

While the link between loneliness and health behaviours in this population remains underexplored, behaviour change theories such as social cognitive theory (SCT [ 44 ]) and the capability, opportunity, and motivation model of behaviour (COM-B [ 45 ]) can complement each other in providing us with possible explanations for this relationship. In line with SCT, it is plausible that individuals with LWBC experiencing loneliness may experience low self-efficacy attributed to feeling a loss of control over their health and how others react [ 14 ], and this lack of confidence can hinder their ability to engage in behaviours such as physical activity [ 46 ]. This is also emphasised by the COM-B model where reduced capability can erode the individual’s confidence and belief in their ability to perform positive health behaviours. Furthermore, the opportunity component of the COM-B model asserts that the environment must make the execution of the behaviour possible [ 45 ]. As lonelier people LWBC may have fewer supportive networks to encourage and facilitate participation in health-promoting behaviours, their opportunity to perform these behaviours can be limited [ 15 ].

The aims of the current study were to (i) describe the prevalence of loneliness in a large sample of LWBC in the UK and (ii) explore associations between loneliness and health behaviours while adjusting for sociodemographic and clinical factors.

Design and participants

The ‘Health and Lifestyle after Cancer’ survey was mailed to patients who had received a diagnosis of breast, prostate, or colorectal cancer between 2012 and 2015 at 10 participating National Health Service (NHS) hospital sites in London and Essex (United Kingdom). Dates of diagnosis for survey administration were chosen because the survey was also used to identify initial interest in the Advancing Survival after Cancer Outcomes Trial (ASCOT) (which included only patients who had completely primary curative treatment) [ 47 ]. Patients were identified by hospital staff and although primarily included patients diagnosed between 2012 and 2015, the final sample for the analysis included patients diagnosed with breast, prostate, or colorectal cancer outside of these dates (range: 1994–2017). As some participants had received a subsequent cancer diagnosis, the date of their most recent breast, prostate, or colorectal cancer diagnosis was reported and used in the analysis. This ranged between 2001 and 2017 in the final sample (mean time in months = 35.5, standard deviation (SD) = 13.6). Survey packs were sent between February 2015 and November 2017 and included a letter of invitation signed by the hospital consultant, a paper version of the survey, and a link to an online version. Participants completed the survey via their preferred method and returned it directly to the research team. Returned questionnaires were accepted until 4th January 2018. No data were collected on non-responders.

Inclusion and exclusion

Inclusion criteria were adults ( ≥  18 years) who had received a diagnosis of breast, prostate, or colorectal cancer in one of the participating hospitals. Survey exclusion criteria were intentionally minimal to make administration at hospital sites as low-burden as possible. Patients were only excluded if it was identified that they were deceased or if hospital staff deemed it inappropriate to send the patient a questionnaire for any other reason (e.g., they had previously requested not to be approached about participation in research).

Ethical approval

This study received ethical approval from the NHS National Research Ethics Committee– South Central Oxford B (reference 14/SC/1369). The initial page of the survey stated that completion and return of the questionnaire meant giving consent for the anonymous collected data to be used in research on lifestyle in people diagnosed with cancer.

Demographic and clinical characteristics

Age was recorded as a continuous variable (in years). Sex (male/female), highest level of education (no formal qualifications/General Certificate of Secondary Education,Vocational or equivalent/A-levelor equivalent/Bachelor’s Degree and above), marital status (married/divorced or separated or widowed or single), and living arrangements (alone/with others) were recorded. Ethnicity information was collected by 15 possible responses to the question “Which of these best describes your ethnic group?”. For cancer-related questions, participants were asked to answer in relation to their most recent cancer diagnosis, given the questionnaire was sent based on their diagnosis of breast, prostate, or colorectal cancer in 2012 or 2013. Participants were asked to report their cancer stage (1/2/3/4/don’t know), but because a high proportion (43%) didn’t know, ‘has your cancer spread’ (yes/no) was used as a proxy (after confirmation from an oncologist that this was acceptable). Cancer treatments (no treatment or active surveillance/surgery/surgery plus one other/other combination of treatment) and time since main treatment completed (< 1 year/1–5 years/on active surveillance) were reported. Time since diagnosis was calculated as the time between their most recent cancer diagnosis date and the date when the questionnaire was received back by the research team (in months). Participants self-reported their comorbidities from a pre-defined list including 15conditions (osteoporosis/diabetes/asthma/emotional or psychiatric illness/stroke/Parkinsons disease/Alzheimer’s disease or dementia/lung disease/arthritis/angina/heart attack/heart murmur/irregular heart rhythm/any other heart trouble/another cancer) and could report any ‘other’ comorbidities that were not present on the list. Total comorbidities were calculated by adding these together and where participants did not report having any of these conditions, this was interpreted as having no comorbidities. Self-reporting of comorbid conditions has shown a high level of accuracy when compared with medical records in people LWBC [ 48 , 49 ].

Exposure: loneliness

Loneliness was assessed using the 3-item short form of the Revised UCLA Loneliness Scale [ 50 ]. The UCLA scale has been the most commonly used to assess loneliness after cancer [ 16 ], and items in the short form are ‘How often do you feel you lack companionship?’, ‘How often do you feel left out?’ and ‘How often do you feel isolated from others?’ with response options: ‘1 = Hardly ever or never’, ‘2 = Some of the time’, and ‘3 = Often’. Scores for each item are summed to create a total loneliness score that can range from 3 to 9. Total scores were not normally distributed, so they were dichotomised to represent higher ( ≥  6) and lower loneliness (< 6). This approach was taken in previous research in the English Longitudinal Study of Ageing [ 32 ], allowing for descriptive comparison of the prevalence of loneliness with a representative sample of older adults in the general population.

Outcomes: health behaviours and BMI

The guidelines for each behaviour for people LWBC were taken from the WCRF/AICR [ 4 ] and national UK guidelines, and these were coded as meeting vs. not meeting guidelines.

Physical activity

Weekly minutes of moderate to vigorous physical activity (MVPA) were assessed using the Godin Leisure Time Exercise Questionnaire (GLTEQ). The GLTEQ is the most commonly used self-report measure of activity in oncology and compares favourably to objective measures [ 51 , 52 , 53 ]. The questionnaire was modified to include a question about duration of activity to allow calculation of minutes of MVPA, which is a very common approach in oncology research [ 52 ]. MVPA was dichotomised as meeting ( ≥  150 min/week) or not meeting (< 150 min/week) recommendations.

The validated Dietary Instrument for Nutrition Education Food Frequency Questionnaire (DINE FFQ) [ 54 ] was used to assess dietary intake including fibre and fat intake, with some food items updated to reflect those currently available and items amended to include red and processed meat estimation [ 47 ]. This measure has been previously validated in the general population [ 54 ] and was chosen after a review of validated food frequency questionnaires and a review of how diet has previously been assessed in people LWBC [ 47 ]. To estimate free sugar, the survey asked about consumption of sugary drinks and fruit juices [ 55 ] and included a custom-made question asking participants to write their total number of teaspoons of added sugar per day. Two items were included to measure the number of daily portions of fruit and vegetables [ 56 ]. This measure has demonstrated sufficient validity when compared against blood chemistry [ 56 , 57 ]. The cut-off scores for meeting the WCRF recommendations were as follows: fruit and vegetables (≥ 5 portions/day), fibre (≥ 30 g Association of Official Analytical Collaboration fibre [ 58 ]/day), free sugar (< 5% calories from free sugars/day), fat (< 33% total energy), red meat (< 500 g/week), and processed meat (none). The scoring system implemented for operationalising meeting or not meeting the recommendations has been described previously [ 59 ].

Alcohol & smoking

Smoking status was collected with a single item from the Health Survey for England to categorise participants as current smokers (not meeting) or non-smokers (meeting) [ 60 ]. Alcohol consumption was self-reported with two items (How often do you have a drink containing alcohol?; How many units of alcohol do you drink on a typical day when you are drinking?), adapted from The Alcohol Use Disorders Identifcation Test consumption questions (AUDIT-C [ 61 ]) which were calculated into an estimate of the average number of units consumed per week. The use of the AUDIT in its original and reduced form has been validated across different contexts and cultures [ 62 ]. Meeting or not meeting this recommendation was operationalised based on the national UK guidelines for alcohol consumption of not exceeding more than 14 units of alcohol per week [ 63 ].

Body mass index

BMI was calculated from participants’ self-reported height and weight. Participants were classified into the following categories: underweight, healthy, overweight, or obese [ 64 ]. Meeting the WCRF recommendation for BMI was operationalised as being classified into the healthy weight category (18.5–24.9 kg/m 2 ).

Demographic and clinical variables that have previously been associated with loneliness and/or health behaviours were included as covariates [ 16 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. This included age, sex, level of education, marital status, and living arrangements. Ethnicity was dichotomised (white/any other ethnicity) due to a very high proportion reporting being white (90%). ‘Has your cancer spread’ was used as a proxy to determine cancer stage. Type of cancer, type of treatment, time since diagnosis, time since completion of main treatment, and number of reported comorbidities were also included.

IBM Statistical Package for the Social Sciences (SPSS) version 26 was used [ 72 ]. Descriptive statistics were used to present participant characteristics and to describe the proportion of people reporting higher versus lower loneliness (Aim i).

Missing value analysis found that 5.5% of 518,348 values were missing and that 27.8% of 5,835 cases had at least 1 piece of missing data. Multiple imputation with 20 iterations was conducted to account for missing data [ 73 ].

To examine whether loneliness was associated with health behaviours (Aim ii), a series of binary logistic regressions were run with loneliness as the exposure, each WCRF health behaviour recommendation as the outcome and adjusting for all covariates. To avoid the ‘Table 2 fallacy’ [ 74 ], only the odds ratio (OR) and 95% confidence interval (CI) for the associations between exposure and outcomes are presented here. Regression analyses were repeated in the non-imputed original data to explore whether findings were similar.

A total of 13,645 surveys were sent, and 5835 were returned (43%response rate). No data were collected on non-responders.

Descriptive statistics

Demographic and clinical characteristics are presented in Table  1 . Participants mean age was 67 years (SD = 12, range 26–97). 44% ( n  = 2553) were male and 56% ( n  = 3266) were female. 48% ( n  = 2786) were living with or beyond breast cancer, 32% ( n  = 1839) prostate and 21% ( n  = 1210) colorectal.

Descriptive data for loneliness and health behaviours are presented in Table  2 . 76% ( n  = 4423) participants reported lower loneliness, and 18% ( n  = 1035) reported higher loneliness. 377 participants (7%) had missing data. Of the 5485 participants who completed the loneliness scale, 81% ( n  = 4423) reported lower and 19% (1035) reported higher loneliness. A descriptive comparison of those with complete data versus imputed data is presented in Additional file 1 .

Regression results

Pooled (20 iterations) associations between loneliness and health behaviours are presented in Table  3 . After adjustment for covariates, those reporting higher levels of loneliness had lower odds of meeting the WCRF recommendations for MVPA (OR 0.78, 95% CI 0.67, 0.97), fruit and vegetables (OR 0.81, CI 0.67, 1.00), and smoking (OR 0.62, 0.46, 0.84), but not other dietary recommendations (fibre, red or processed meat, sugar, fat– OR and CIs presented in Table  3 ), alcohol (OR 0.89, CI 0.67, 1.19) or BMI (0.79, CI 0.46, 1.16).

Analysis with the original data

Logistic regression analyses with the complete case data showed similar associations to the imputed data (see Additional file 1 ).

In this sample of 5835 people LWBC, 76% reported experiencing lower levels of loneliness, while 18% reported higher loneliness. Individuals who reported higher levels of loneliness were less likely to meet the WCRF recommendations for MVPA, fruit and vegetable intake, and smoking (i.e. they are less likely to do the recommended levels of activity (150 min a week), they are less likely to eat 5 portions of fruit and vegetables a day and they are more likely to be smokers). No association was observed between loneliness and meeting the recommendations for fibre, red or processed meat, fat, sugar, or alcohol and BMI.

The results of this study demonstrate slightly lower levels of loneliness in people diagnosed with breast, prostate, or colorectal cancer than previous studies conducted in people LWBC (22-36%) [ 75 , 76 ]. This discrepancy might be attributed to the dichotomisation of UCLA scores in this study, resulting in an arbitrary definition of being lonely or not lonely. It therefore is not directly comparable to other studies using different scales and thresholds, for example, De Boer and colleague’s study in breast cancer patients used the De Jong Gierveld Scale [ 66 ], where a score above three was interpreted to mean experiencing loneliness [ 76 ]. However, where the same scale and threshold for loneliness was applied in the general population in the UK, the prevalence of loneliness in people LWBC was similar (16%; [ 32 ]). Differences in the prevalence of loneliness may also be attributed to the timing of the study, with the majority (70%) of participants being 1 to 5 years post finishing their primary treatment. Loneliness levels are likely to fluctuate considerably within this period, with loneliness scores in studies conducted during or just after initial treatment for cancer being significantly lower than loneliness scores in studies conducted in participants more than a year after diagnosis [ 16 ]. This finding is also supported by qualitative research [ 15 , 77 ] and may be attributed to the plausible increase in social support in the period immediately after diagnosis and initial treatment [ 75 ].

Although the effect size observed was small, the results of this study converge with previous research reporting a decreased likelihood of engaging in physical activity in people who report higher levels of loneliness [ 18 ] and extend sparse findings of an association between loneliness and physical activity in people LWBC [ 34 , 35 ]. Lemij and colleagues' study in older women (aged 70+) diagnosed with breast cancer reported that increasing loneliness was associated with lower levels of physical activity over time [ 46 ]. Although the current study used a different approach to dichotomise physical activity and loneliness, the results still support this inverse association in a younger, larger sample of adults diagnosed with breast, prostate, or colorectal cancer. This is important because there is strong evidence of improved outcomes for people LWBC who engage in higher levels of physical activity, including increased chances of survival and improvements in psychosocial outcomes [ 20 , 78 , 79 ]. Although this study was cross-sectional, it has identified a need for the consideration of psychosocial variables such as loneliness in efforts to increase physical activity in this population. While physical activity interventions in oncology often include a social component and encourage social support [ 80 , 81 ], a more targeted approach may be needed to address the subjective experience of loneliness. Given the distinction between social isolation and loneliness, efforts to increase social contact and social support may not necessarily address aspects of loneliness, including sense of belonging and feeling cared for by others [ 82 ]. Supporting this, Dowd and colleagues reported that an intervention where physical activity was framed as being beneficial for both health and social skills led to increased engagement in physical activity while simultaneously improving loneliness in university students [ 83 ]. The results of the current study provide scope for investigating whether this type of interventional approach may also show promise in people LWBC.

The WCRF recommends that people LWBC follow a healthy diet by adhering to the published dietary recommendations for primary cancer prevention [ 23 ]. To the authors’ knowledge, this is the first study to quantitatively explore loneliness and specific dietary component intake in people LWBC and highlights that experiencing loneliness may contribute to making poorer dietary choices. Given the sparse evidence base, more research is needed to understand the potential reasons for a lack of association between loneliness and meeting the recommendations for red and processed meat, fat, fibre, and alcohol. In the current study, this may be due to the limited variation in the sample, with a high percentage of participants meeting some of the recommendations (e.g., red meat and alcohol). Loneliness was associated with fruit and vegetable consumption in this sample, where participants who reported experiencing higher levels of loneliness were less likely to meet this dietary recommendation. However, it is important to note that this effect size was small, and the confidence intervals suggest that the impact of loneliness on intake of fruit and vegetable may be relatively weak. Richard and colleagues’ also found that lonelier men and women in a Swiss national survey had worse adherence to the recommendations for fruit and vegetables, although their study measured adherence using a subjective question on whether they perceive that they meet the recommendations, rather than being calculated from a food frequency questionnaire [ 84 ]. The observed association in this study is small, but diverges from Kobayashi and colleagues’ finding of no relationship between meeting the fruit and vegetable recommendations and loneliness in the UK general population [ 32 ], and instead suggests that people diagnosed with cancer may be particularly susceptible to the negative impact of loneliness on their eating behaviours. More research is needed to investigate the potential mechanisms that underlie this relationship, to ultimately inform targeted intervention design in this population.

Our finding that loneliness was associated with smoking in people LWBC is in line with findings from a systematic review of loneliness and smoking, whereby lonely people were more likely to be smokers [ 36 ]. More recently, this association has also been found in a longitudinal analysis of the UK Biobank data, where Eloivaino and colleagues reported that smoking, alcohol, and physical activity accounted for 32-54% of the excess risk of mortality associated with loneliness in the general population [ 85 ]. Furthermore, previous research indicates a bidirectional association, where smokers are also more likely to experience higher loneliness over time [ 37 ]. In the current study, the possibility of reverse causality in associations between loneliness and health behaviours cannot be ruled out. Specifically, it is possible that loneliness may be influenced by engagement in certain health behaviours. However, with the available cross-sectional data, it is challenging to determine the temporal ordering to provide a more comprehensive understanding of causality in the observed associations. In any case, bidirectional evidence suggests a vicious cycle wherein loneliness and unfavourable health behaviours reinforce one another [ 27 , 36 , 37 ]. Further research, particularly longitudinal studies, is needed to unravel the complexities of the relationship between loneliness and health behaviours and to understand the directionality and underlying mechanisms involved. Using a longitudinal design would also help identify if there are critical periods where loneliness may be particularly influential on health behaviours. This is particularly important for this population as people LWBC move between the phases of diagnosis, treatment, and survivorship and each of these phases present unique demands and challenges to the individual [ 86 ].

The mechanisms linking loneliness and health behaviours remain relatively unexplored, but it is important to acknowledge the potential mediating role of depression. Loneliness and depression are considered to be reciprocally associated [ 9 , 87 ], therefore, it may be that depression lies on a causal pathway where negative affect resulting from loneliness impacts health behaviours [ 32 ]. As the data were cross-sectional, no mediation analysis was conducted and accordingly, depression was not included in the model as it was deemed inappropriate to control for potential mediators [ 88 , 89 ]. Additionally, social interactions and norms can shape health behaviours and lonelier people may not be as exposed to others engaging in practices such as healthy eating and exercise due to reduced social engagement [ 90 , 91 ]. In line with the recognition of the social environment in SCT [ 44 ] and the opportunity component of the COM-B model [ 45 ], studies in both the general population and people LWBC have demonstrated that witnessing health-promoting behaviours is associated with increased likelihood of engaging in these behaviours [ 92 , 93 , 94 , 95 ]. Lastly, as demonstrated in Newall and colleagues’ study in the general population, happiness may moderate this association whereby higher levels of happiness may weaken the association between loneliness and unhealthy behaviours [ 29 ]. This may be attributed to the broadening influence of positive emotions, which can counteract the negative impact of loneliness [ 29 , 96 ]. Future research should employ qualitative methods to uncover the nuances in these associations and to explore potential mechanisms. For example, qualitative interviews with a sample of people with type 2 diabetes revealed reduced motivation due to loneliness and reduced social contact inhibited engagement in physical activity during the COVID-19 pandemic [ 97 ].

The results of this study can inform policy and practice by directing support toward the creation of environments that promote social connections and reduce loneliness in this population. Addressing loneliness is a key part of public health agendas with strategies such as social prescribing being implemented into the NHS Long Term Plan [ 98 ]. This type of approach aims to combat loneliness by enabling individuals to co-develop solutions to help them cope with their health, while developing connections with communities and building social engagement [ 99 , 100 ]. The impact of this approach on reducing the negative effect of loneliness on health behaviours has yet to be explored in people LWBC, but combining strategies that target both elements simultaneously shows promise in this population [ 101 ].

Strengths of the study include the use of multiple imputation to overcome any bias or loss of statistical power introduced by only performing complete case analyses [ 102 ]. Despite limitations in establishing causality, a strength of the cross-sectional design of this study is that it allowed for the identification of a new area of inquiry that requires attention, and the observed associations can help inform theory development and intervention design [ 103 , 104 ]. While the ease with which a self-report survey can be distributed to many people is a strength of this type of research, the validity of health research can be threatened by selection biases [ 105 ]. In this study, 43% of those sent the initial letter completed the survey. Previous research has demonstrated that people who agree to take part in questionnaire asking about their health behaviours often demonstrate a higher interest in their health and improving health behaviours [ 106 , 107 ]. Therefore, selection biases may threaten the generalisability of our findings. Limitations of this study also include that this was not an ethnically diverse sample of LWBC, with 90% of participants identifying as white. Another limitation was the use of self-report for recording health behaviours, which might be subject to recall errors and social desirability [ 108 ]. Additionally, inherent in research is the limitation of unmeasured confounders that may have contributed to the results. In this study, direct measures of socioeconomic position (e.g., level of income) were not included in the survey and regression model. However, the observed associations remained even after controlling for education level, a variable that has been previously identified as the strongest independent predictor of health behaviours among people LWBC out of three variables indicative of socioeconomic position (including household income and occupation type) [ 109 ]. Lastly, some dietary instruments were custom-made for this study, for example, the free sugar measure and this may threaten their validity. However, any adaptations were made based on a review of available measures alongside the main components of the UK diet [ 47 ], and modifications were made to validated measures used in previous population level research [ 54 , 110 ].

This study reports a similar prevalence of loneliness in people diagnosed with breast, prostate, and colorectal cancer in the UK to that observed in the general population and identifies the need to consider the impact of loneliness on health behaviours in this population. Given the associations between loneliness and physical activity, smoking, and fruit and vegetable consumption, future studies should aim to explore the factors predicting higher levels of loneliness in this population, to identify the people LWBC who are most at risk. Additionally, the mechanisms that might explain the association between loneliness and these health behaviours remain unexplored and future research and care would benefit from exploring why these relationships exist. Particularly following the COVID-19 pandemic and the associated heightened prevalence of loneliness among LWBC [ 111 , 112 ], future research should aim to take a holistic view of the cancer experience and target aspects of loneliness in health behaviour intervention design.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author upon reasonable request.

Abbreviations

American Institute for Cancer Research

Alcohol Use Disorders Identification Test consumption questions

body mass index

confidence interval

Dietary Instrument for Nutrition Education Food Frequency Questionnaire

English longitudinal Study of Ageing

General Certificate of Secondary Education

Godin leisure time exercise questionnaire

living with and beyond cancer

moderate-to-vigorous physical activity

National Health Service

Statistical Package for Social Sciences

United Kingdom

World Cancer Research Fund

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Acknowledgements

The authors thank Cancer Research UK (grant number C1418/A14133) for funding the Advancing Survivorship Cancer Outcomes Trial (ASCOT (47)), from which the survey data used in this study was obtained.

This work was funded by Cancer Research UK (grant number C1418/A14133).

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Rebecca J Beeken and Abi Fisher are joint senior authors.

Authors and Affiliations

Department of Behavioural Science and Health, University College London, Gower Street, WC1E 6BT, London, UK

Susan Smith, Andrew Steptoe & Abi Fisher

Department of Psychological Sciences, University of Surrey, GU2 7XH, Guildford, Surrey, UK

Phillippa Lally

MRC Epidemiology Unit, Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, CB2 0QQ, Cambridge, Box 285, UK

Yanaina Chavez-Ugalde

Leeds Institute of Health Sciences, University of Leeds, LS2 9JT, Leeds, UK

Rebecca J Beeken

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RB and AF were responsible for the funding acquisition and are joint study leads. AS, AF, and YC contributed to the study conception and design. PL was responsible for the data curation and cleaning. Data analysis was performed by AF. SS and AF interpreted the data and wrote the manuscript. All authors contributed to the manuscript revision. All authors read and approved the final manuscript.

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Correspondence to Abi Fisher .

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This study received ethical approval from the NHS National Research Ethics Committee– South Central Oxford B (reference 14/SC/1369). Informed consent was obtained from all participants.

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Smith, S., Lally, P., Steptoe, A. et al. Prevalence of loneliness and associations with health behaviours and body mass index in 5835 people living with and beyond cancer: a cross-sectional study. BMC Public Health 24 , 635 (2024). https://doi.org/10.1186/s12889-024-17797-3

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Received : 19 October 2023

Accepted : 17 January 2024

Published : 28 February 2024

DOI : https://doi.org/10.1186/s12889-024-17797-3

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