Knowledge Synthesis

There are many different types of knowledge synthesis. Choose the right type based on:

• The type of research question
• The type of evidence (qualitative, quantitative)
• Approach to synthesis (meta-analysis, narrative synthesis, meta-synthesis)
• Philosophical / theoretical perspectives (relevant in qualitative reviews)
• Available time and resources

Resources for choosing a review type

• Journal articles that describe and compare review types:
  • Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91–108. https://doi.org/10.1111/j.1471-1842.2009.00848.x
  • Munn, Z., Stern, C., Aromataris, E., Lockwood, C., & Jordan, Z. (2018). What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences. BMC Medical Research Methodology, 18(1), 5–5. https://doi.org/10.1186/s12874-017-0468-4
  • Sutton, A., Clowes, M., Preston, L., & Booth, A. (2019). Meeting the review family: exploring review types and associated information retrieval requirements. Health Information and Libraries Journal, 36(3), 202–222. https://doi.org/10.1111/hir.12276

• A systematic review seeks to answer a specific research question by identifying, selecting, critically appraising, and synthesizing all relevant research.
• Some examples of possible systematic review research questions:
  • Do riparian forest buffers reduce phosphorus loading into fresh waters from cropland compared to cropland without riparian forest buffers?
  • Is prophylactic vaccination of poultry a cost-effective method of controlling the spread of avian influenza compared to emergency vaccination?
  • How effective are ADHD medications in reducing ADHD symptoms in children with an ADHD diagnosis?

Resources for conducting a systematic review

• Scoping reviews seek to map the existing literature on a topic.
• Some examples of possible scoping review research questions:
  • What methods for quantifying nonpoint source phosphorus loading into fresh waters are described in the literature?
  • What government policies related to vaccination for preventing outbreaks of human-livestock zoonoses exist in jurisdictions around the world?
  • What randomized controlled trials of ADHD medications measure sleep-related outcomes?

Resources for conducting a scoping review

• Arksey, H., & O’Malley, L. (2005). Scoping studies: towards a methodological framework. International Journal of Social Research Methodology, 8(1), 19–32. https://doi.org/10.1080/1364557032000119616
  The is a classic reference for conducting a scoping review, but it has been superseded by newer guidance:

This guide focuses on systematic reviews and scoping reviews. However, many of the principles and resources provided will be useful for other types of knowledge synthesis.

Resources for conducting other types of knowledge synthesis

• Integrative reviews
  • Whittemore, R., & Knafl, K. (2005). The integrative review: updated methodology. Journal of Advanced Nursing, 52(5), 546–553. https://doi.org/10.1111/j.1365-2648.2005.03621.x
• Umbrella reviews
  • JBI Manual for Evidence Synthesis, Chapter 9: Umbrella Reviews
• Rapid reviews
  • Garritty, C., Hamel, C., Trivella, M., Gartlehner, G., Nussbaumer-Streit, B., Devane, D., Kamel, C., Griebler, U., & King, V. J. (2024). Updated recommendations for the Cochrane rapid review methods guidance for rapid reviews of effectiveness. BMJ (Online), 384, e076335–e076335. https://doi.org/10.1136/bmj-2023-076335
• Realist reviews
  • The RAMESES Projects: A website that provides resources for conducting realist reviews.
  • Pawson, R., Greenhalgh, T., Harvey, G., & Walshe, K. (2005). Realist review – a new method of systematic review designed for complex policy interventions. Journal of Health Services Research & Policy, 10(1_suppl), 21–34. https://doi.org/10.1258/1355819054308530

• While knowledge syntheses originated in the health sciences, knowledge synthesis methods are widespread across many different disciplines.
• To understand best practices for knowledge syntheses in your discipline:
  • look at published knowledge syntheses in disciplinary journals
  • consult articles discussing knowledge synthesis in your discipline