Evidence Synthesis: What is Evidence Synthesis?

Librarians are typically unable to serve as co-authors or co-researchers given workload demands. However, librarians can assist evidence synthesis studies in numerous ways, including providing the following:

• An overview of best practices for conducting systematic reviews and other evidence syntheses in your discipline
• Guidance in selecting and formulating a research question
• Advice on which review type (e.g. systematic, scoping, rapid, umbrella, etc.) best suits your question
• Advice on drafting and selecting a register for your systematic review protocol
• Guidance on selecting databases and platforms to search
• Support choosing search terms and developing a search strategy
• Assistance finding the full text of articles and other sources you’re planning to include in your review
• Recommending/training in the use of citation management software to organize and deduplicate results (e.g. Zotero), and free article screening tools (e.g. Rayyan)
• Review draft of methods section

*Initial consultations are typically an hour. 

Four Common Types of Evidence Synthesis:

Scoping Review: Systematically and transparently collects and categorizes existing evidence on a broad topic or set of research questions.

• Research question can be broad.
  • Example question format: "What interventions are used to address outcomes X in population Y?" or, "What are the characteristics of the literature on interventions X in setting Y?"
• May critically evaluate existing evidence, but does not attempt to synthesize the results in the way a systematic review would.
• Often takes longer than a systematic review.

Systematic Review: A methodical and comprehensive literature synthesis focused on a well-formulated research question.

• Answers a question of whether or not an intervention is effective.
  • Example question format: "What is the effect of intervention X on population Y in achieving outcomes Z?"
• Aims to identify and synthesize all of the scholarly research on a particular topic, including both published and unpublished studies.
• May involve a meta-analysis.
• Much more time-intensive than traditional literature reviews.

Rapid Review: Applies systematic review methodology within a time-constrained setting.

• Employs methodological “shortcuts” (limiting search terms for example) at the risk of introducing bias.
• Useful for addressing issues needing quick decisions.

Meta-Analysis: A statistical technique for combining the findings from disparate quantitative studies.

• Uses statistical methods to objectively evaluate, synthesize, and summarize results.
• May be conducted independently or as part of a systematic review.

*Example question formats and explanations drawn from the Evidence Synthesis Institute.