Evidence Synthesis Guide : Evidence Synthesis Decision Tree

Common types of evidence synthesis include: 
 

​​Systematic Review

• Systematically and transparently collect and categorize existing evidence on a broad question of scientific, policy or management importance.
• Compares, evaluates, and synthesizes evidence in a search for the effect of an intervention. 
• Time-intensive and often take months to a year or more to complete. 
• The most commonly referred to type of evidence synthesis. Sometimes confused as a blanket term for other types of reviews.
   

​​Literature (Narrative) Review

• A broad term referring to reviews with a wide scope and non-standardized methodology. 
• Search strategies, comprehensiveness, and time range covered will vary and do not follow an established protocol.
   

​Scoping Review or Evidence Map

• Systematically and transparently collect and categorize existing evidence on a broad question of scientific, policy or management importance.
• Seeks to identify research gaps and opportunities for evidence synthesis rather than searching for the effect of an intervention. 
• May critically evaluate existing evidence, but does not attempt to synthesize the results in the way a systematic review would. 
• May take longer than a systematic review.
   

​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, such as developing policy recommendations.

 

Umbrella Review

• Reviews other systematic reviews on a topic. 
• Often defines a broader question than is typical of a traditional systematic review.
• Most useful when there are competing interventions to consider.
   

Meta-analysis

• 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.