What is a knowledge synthesis? - Knowledge Syntheses - Systematic Reviews, Scoping Reviews and More - Library Guides at Trent University Library

What is Knowledge Synthesis?

"A knowledge synthesis attempts to summarize all pertinent studies on a specific question, can improve the understanding of inconsistencies in diverse evidence, and can identify gaps in research evidence to define future research agendas."¹

The research methodology of knowledge synthesis varies across disciplines and comprises several types of reviews (quantitative, qualitative or mixed) including, but not limited to narrative, systematic, scoping, integrative, rapid, and realist.

Included on this page are:

lists of review types and their descriptions
links to articles exemplifying a selection of review types

Which review is that? A guide to review types

Librarians at the University of Melbourne, Australia, have developed a comprehensive guide describing the many types of reviews - Which review is that? A guide to review types. The image below illustrates the reviews that are described in detail in their guide.

Birkic, V., Celeste, T., & Cochrane, L. (2020). Which review is that? A guide to review types, Available from https://unimelb.libguides.com/whichreview

Synthesis Comparison Chart

A selection of the common review types found in the literature as presented and compared in the following table adapted from Grant and Booth.²

Name	Description	Search	Assessment	Synthesis	Analysis
Critical review	Aims to demonstrate writer has extensively researched literature and critically evaluated its quality. Goes beyond mere description to include degree of analysis and conceptual innovation. Typically results in hypothesis or mode	Seeks to identify most significant items in the field	No formal quality assessment. Attempts to evaluate according to contribution	No formal quality assessment. Attempts to evaluate according to contribution	Significant component: seeks to identify conceptual contribution to embody existing or derive new theory
Literature review	Generic term: published materials that provide examination of recent or current literature. Can cover wide range of subjects at various levels of completeness and comprehensiveness. May include research findings	May or may not include comprehensive searching	May or may not include quality assessment	Typically narrative	Analysis may be chronological, conceptual, thematic, etc.
Mapping review/ systematic map	Map out and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in research literature	Completeness of searching determined by time/scope constraints	No formal quality assessment	May be graphical and tabular	Characterizes quantity and quality of literature, perhaps by study design and other key features. May identify need for primary or secondary research
Meta-analysis	Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results. Often used within a systematic review	Aims for exhaustive, comprehensive searching. May use funnel plot to assess completeness	Quality assessment may determine inclusion/ exclusion and/or sensitivity analyses	Graphical and tabular with narrative commentary	Numerical analysis of measures of effect assuming absence of heterogeneity
Mixed Methods Review	Refers to a combination of review approaches for example combining quantitative with qualitative research or outcome with process studies.	Requires either very sensitive search to retrieve all studies or separately conceived quantitative and qualitative strategies	Requires either a generic appraisal instrument or separate appraisal processes with corresponding checklists	Typically both components will be presented as narrative and in tables. May also employ graphical means of integrating quantitative and qualitative studies	Analysis may characterise both literatures and look for correlations between characteristics or use gap analysis to identify aspects absent in one literature but missing in the other
Overview	Generic term: summary of the [medical] literature that attempts to survey the literature and describe its characteristics	May or may not include comprehensive searching (depends whether systematic overview or not)	May or may not include quality assessment (depends whether systematic overview or not)	Synthesis depends on whether systematic or not. Typically narrative but may include tabular features	Analysis may be chronological, conceptual, thematic, etc.
Qualitative Review	Method for integrating or comparing the findings from qualitative studies. It looks for ‘themes’ or ‘constructs’ that lie in or across individual qualitative studies	May employ selective or purposive sampling	Quality assessment typically used to mediate messages not for inclusion/exclusion	Qualitative, narrative synthesis	Thematic analysis, may include conceptual models
Rapid review	Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research	Completeness of searching variable, determined by time constraints	Time-limited formal quality assessment	Typically narrative and tabular	Quantities of literature and overall quality/direction of effect of literature
Scoping review	Preliminary assessment of potential size and scope of available research literature. Aims to identify nature and extent of research evidence (usually including ongoing research)	Completeness of searching determined by time/scope constraints. May include research in progress	No formal quality assessment	Typically tabular with some narrative commentary	Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review
State-of-the-art review	Tend to address more current matters in contrast to other combined retrospective and current approaches. May offer new perspectives on issues or point out areas for further research	Aims for comprehensive searching of current literature	No formal quality assessment	Typically narrative, may have tabular accompaniment	Current state of knowledge and priorities for future investigation and research
Systematic Review	Seeks to systematically search for, appraise and synthesise research evidence, ideally adhering to guidelines on the conduct of a review.	Aims for exhaustive, comprehensive searching.	Quality assessment may determine inclusion/exclusion.	Typically narrative with tabular accompaniment.	What is known; recommendations for practice. What remains unknown; uncertainty around findings, recommendations for future research.
Systematized Review	Attempt to include elements of systematic review process while stopping short of a systematic review. Typically conducted as a postgraduate student assignment	May or may not include comprehensive searching	May or may not include quality assessment	Typically narrative with tabular accompaniment	What is known; uncertainty around findings; limitations of methodology
Umbrella Review	Compiles evidence from multiple reviews into one easily digestible document. Focuses on a broad condition or problem where there are competing interventions and highlights these interventions and their results.	Identification of reviews only, search does not include primary studies	Quality assessment of studies within component reviews and/or of reviews themselves	Graphical and tabular with narrative commentary	What is known; recommendations for practice. What remains unknown; recommendations for further research

Examples of published syntheses

Bengtsson, V., Berglund, L., & Aasa, U. (2018). Narrative review of injuries in powerlifting with special reference to their association to the squat, bench press and deadlift. BMJ Open Sport & Exercise Medicine, 4(1), e000382–e000382. https://doi.org/10.1136/bmjsem-2018-000382.

Latchmore, T., Schuster-Wallace, C. J., Longboat, D. R., Dickson-Anderson, S. E., & Majury, A. (2018). Critical elements for local Indigenous water security in Canada: A narrative review. Journal of Water and Health, 16(6), 893–903. https://doi.org/10.2166/wh.2018.107.

Younas, A., & Maddigan, J. (2019). Proposing a policy framework for nursing education for fostering compassion in nursing students: A critical review. Journal of Advanced Nursing, 75(8), 1621–1636. https://doi.org/10.1111/jan.13946

Rew, L., Young, C. C., Monge, M., & Bogucka, R. (2021). Review: Puberty blockers for transgender and gender diverse youth—a critical review of the literature. Child and Adolescent Mental Health, 26(1), 3–14. https://doi.org/10.1111/camh.12437

Steg, L., & Vlek, C. (2009). Encouraging pro-environmental behaviour: An integrative review and research agenda. Journal of Environmental Psychology, 29(3), 309–317. https://doi.org/10.1016/j.jenvp.2008.10.004

Hugelius, K., Harada, N., & Marutani, M. (2021). Consequences of visiting restrictions during the COVID‐19 pandemic: An integrative review. International Journal of Nursing Studies, 121, 104000–104000. https://doi.org/10.1016/j.ijnurstu.2021.104000

Stormacq, C., Van den Broucke, S., & Wosinski, J. (2019). Does health literacy mediate the relationship between socioeconomic status and health disparities? Integrative review. Health Promotion International, 34(5), e1–e17. https://doi.org/10.1093/heapro/day062

Cheng, S. H., MacLeod, K., Ahlroth, S., Onder, S., Perge, E., Shyamsundar, P., … Miller, D. C. (2019). A systematic map of evidence on the contribution of forests to poverty alleviation. Environmental Evidence, 8(1), 3. https://doi.org/10.1186/s13750-019-0148-4

Wijn, S. R. W., Rovers, M. M., & Hannink, G. (2022). Confounding adjustment methods in longitudinal observational data with a time-varying treatment: a mapping review. BMJ Open, 12(3), e058977–e058977. https://doi.org/10.1136/bmjopen-2021-058977

Abou Ghayda, R., Lee, K. H., Han, Y. J., Ryu, S., Hong, S. H., Yoon, S., Jeong, G. H., Yang, J. W., Lee, H. J., Lee, J., Lee, J. Y., Effenberger, M., Eisenhut, M., Kronbichler, A., Solmi, M., Li, H., Jacob, L., Koyanagi, A., Radua, J., … Shin, J. I. (2022). The global case fatality rate of coronavirus disease 2019 by continents and national income: A meta‐analysis. Journal of Medical Virology, 94(6), 2402–2413. https://doi.org/10.1002/jmv.27610

Hossie, T., Landolt, K., & Murray, D. L. (2017). Determinants and co‐expression of anti‐predator responses in amphibian tadpoles: a meta‐analysis. Oikos, 126(2), 173-n/a. https://doi.org/10.1111/oik.03305

Hurley, M., Dickson, K., Hallett, R., Grant, R., Hauari, H., Walsh, N., Stansfield, C., & Oliver, S. (2018). Exercise interventions and patient beliefs for people with hip, knee or hip and knee osteoarthritis: A mixed methods review. Cochrane Database of Systematic Reviews, 2018(4), CD010842–CD010842. https://doi.org/10.1002/14651858.CD010842.pub2

Broadway-Horner, M., & Kar, A. (2022). Looking into the LGB affirmative therapies over the last fifty years - a mixed method review synthesis. International Review of Psychiatry (Abingdon, England), 34(3–4), 392–401. https://doi.org/10.1080/09540261.2022.2051443

Lo, C. K. (2023). What Is the Impact of ChatGPT on Education? A Rapid Review of the Literature. Education Sciences, 13(4), 410-. https://doi.org/10.3390/educsci13040410.

Schlief, M., Saunders, K. R. K., Appleton, R., Barnett, P., Vera San Juan, N., Foye, U., Olive, R. R., Machin, K., Shah, P., Chipp, B., Lyons, N., Tamworth, C., Persaud, K., Badhan, M., Black, C.-A., Sin, J., Riches, S., Graham, T., Greening, J., … Johnson, S. (2022). Synthesis of the Evidence on What Works for Whom in Telemental Health: Rapid Realist Review. Interactive Journal of Medical Research, 11(2), e38239–e38239. https://doi.org/10.2196/38239

Abboah-Offei, M., Salifu, Y., Adewale, B., Bayuo, J., Ofosu-Poku, R., & Opare-Lokko, E. B. A. (2021). A rapid review of the use of face mask in preventing the spread of COVID-19. International Journal of Nursing Studies Advances, 3, 100013–100013. https://doi.org/10.1016/j.ijnsa.2020.100013

Darvesh, N., Radhakrishnan, A., Lachance, C. C., Nincic, V., Sharpe, J. P., Ghassemi, M., Straus, S. E., & Tricco, A. C. (2020). Exploring the prevalence of gaming disorder and Internet gaming disorder: A rapid scoping review. Systematic Reviews, 9(1), 68–68. https://doi.org/10.1186/s13643-020-01329-2

Noone, C., McSharry, J., Smalle, M., Burns, A., Dwan, K., Devane, D., & Morrissey, E. C. (2020). Video calls for reducing social isolation and loneliness in older people: A rapid review. Cochrane Database of Systematic Reviews, 5(5), 1–40. https://doi.org/10.1002/14651858.CD013632

Aunger, J. A., Millar, R., Greenhalgh, J., Mannion, R., Rafferty, A. M., & McLeod, H. (2021). Why do some inter-organisational collaborations in healthcare work when others do not? A realist review. Systematic Reviews, 10(1), 82–82. https://doi.org/10.1186/s13643-021-01630-8

Gilmer, C., Buchan, J. L., Letourneau, N., Bennett, C. T., Shanker, S. G., Fenwick, A., & Smith-Chant, B. (2016). Parent education interventions designed to support the transition to parenthood: A realist review. International Journal of Nursing Studies, 59, 118–133. https://doi.org/10.1016/j.ijnurstu.2016.03.015

Zhang, L., Mersky, J. P., Gruber, A. M. H., & Kim, J.-Y. (2023). Intergenerational Transmission of Parental Adverse Childhood Experiences and Children’s Outcomes: A Scoping Review. Trauma, Violence & Abuse, 24(5), 3251–3264. https://doi.org/10.1177/15248380221126186

Omar, A., Cumal, A., Vellani, S., Krassikova, A., Lapenskie, J., Bayly, M., Welch, V. A., Ghogomu, E., Iaboni, A., & McGilton, K. S. (2021). Health and social interventions to restore physical function of older adults post-hip fracture: a scoping review. BMJ Open, 11(10), e053992–e053992. https://doi.org/10.1136/bmjopen-2021-053992

Bowers, R., Turner, G., Graham, I. D., Furgal, C., & Dubois, L. (2020). Piecing together the Labrador Inuit food security policy puzzle in Nunatsiavut, Labrador (Canada): a scoping review. International Journal of Circumpolar Health, 79(1), 1799676-. https://doi.org/10.1080/22423982.2020.1799676

Roy, P. K., Saumya, S., Singh, J. P., Banerjee, S., & Gutub, A. (2023). Analysis of community question‐answering issues via machine learning and deep learning: State‐of‐the‐art review. CAAI Transactions on Intelligence Technology., 8(1), 95–117. https://doi.org/10.1049/cit2.12081

Wang, L., Kolios, A., Liu, X., Venetsanos, D., & Cai, R. (2022). Reliability of offshore wind turbine support structures: A state-of-the-art review. Renewable & Sustainable Energy Reviews, 161, 112250-. https://doi.org/10.1016/j.rser.2022.112250

Sun, G., Chen, D., Zhu, G., & Li, Q. (2022). Lightweight hybrid materials and structures for energy absorption: A state-of-the-art review and outlook. Thin-Walled Structures, 172. https://doi.org/10.1016/j.tws.2021.108760

Sun, J., Norouzi, O., & Mašek, O. (2022). A state-of-the-art review on algae pyrolysis for bioenergy and biochar production. Bioresource Technology, 346. https://doi.org/10.1016/j.biortech.2021.126258

McDermott, E., & Graham, H. (2005). Resilient Young Mothering: Social Inequalities, Late Modernity and the ‘Problem’ of ‘Teenage’ Motherhood. Journal of Youth Studies, 8(1), 59–79. https://doi.org/10.1080/13676260500063702

Odendaal, W. A., Anstey Watkins, J., Leon, N., Goudge, J., Griffiths, F., Tomlinson, M., & Daniels, K. (2020). Health workers’ perceptions and experiences of using mHealth technologies to deliver primary healthcare services: a qualitative evidence synthesis. Cochrane Database of Systematic Reviews, 2020(3), CD011942–CD011942. https://doi.org/10.1002/14651858.CD011942.pub2

Joo, J. Y., & Liu, M. F. (2021). Nurses’ barriers to caring for patients with COVID‐19: a qualitative systematic review. International Nursing Review, 68(2), 202–213. https://doi.org/10.1111/inr.12648

Dauwan, M., Begemann, M. J. H., Slot, M. I. E., Lee, E. H. M., Scheltens, P., & Sommer, I. E. C. (2021). Physical exercise improves quality of life, depressive symptoms, and cognition across chronic brain disorders: a transdiagnostic systematic review and meta-analysis of randomized controlled trials. Journal of Neurology, 268(4), 1222–1246. https://doi.org/10.1007/s00415-019-09493-9

Fisher, E., Eccleston, C., Degenhardt, L., Finn, D. P., Finnerup, N. B., Gilron, I., Haroutounian, S., Krane, E., Rice, A. S. C., Rowbotham, M., Wallace, M., & Andrew Moore, R. (2019). Cannabinoids, cannabis, and cannabis-based medicine for pain management: A protocol for an overview of systematic reviews and a systematic review of randomised controlled trials. Pain Reports, 4(3), e741–e741. https://doi.org/10.1097/PR9.0000000000000741

Muzenda, T., Dambisya, P. M., Kamkuemah, M., Gausi, B., Battersby, J., & Oni, T. (2022). Mapping food and physical activity environments in low- and middle-income countries: A systematised review. Health & Place, 75, 102809–102809. https://doi.org/10.1016/j.healthplace.2022.102809

Sinkovics, N., Gunaratne, D., Sinkovics, R. R., & Molina-Castillo, F.-J. (2021). Sustainable Business Model Innovation: An Umbrella Review. Sustainability, 13(13), 7266-. https://doi.org/10.3390/su13137266

Grgic, J., Grgic, I., Pickering, C., Schoenfeld, B. J., Bishop, D. J., & Pedisic, Z. (2020). Wake up and smell the coffee: caffeine supplementation and exercise performance—an umbrella review of 21 published meta-analyses. British journal of sports medicine, 54(11), 681–688. https://doi.org/10.1136/bjsports-2018-100278

Bonaccorsi, G., Manzi, F., Del Riccio, M., Setola, N., Naldi, E., Milani, C., Giorgetti, D., Dellisanti, C., & Lorini, C. (2020). Impact of the Built Environment and the Neighborhood in Promoting the Physical Activity and the Healthy Aging in Older People: An Umbrella Review. International Journal of Environmental Research and Public Health, 17(17), 6127-. https://doi.org/10.3390/ijerph1717612

References

Kastner, M. et al. What is the most appropriate knowledge synthesis method to conduct a review? Protocol for a scoping review. BMC Med. Res. Methodol. 12, 114 (2012).
Grant, M.J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91-108. https://doi.org/10.1111/j.1471-1842.2009.00848.x