Evidence synthesis refers to any method of identifying, selecting, and combining results from multiple studies. For help selecting a methodology, try the Cornell University review methodology decision tree.
Types of evidence synthesis include:
Narrative Literature Reviews
- Provides an overview and critical discussion of the literature on a broad topic and a qualitative summary without a strict methodology.
- Search strategies, comprehensiveness, and time range covered will vary and do not follow an established protocol.
Scoping Reviews
- Maps the existing literature on a broad topic and identifies gaps in research.
- May critically evaluate existing evidence, but does not attempt to synthesise the results in the way a systematic review would.
Mapping Reviews
- This type of review will incorporate a geographical mapping exercise or charting of the data in a tabular or any other visual format that can plot or portray the data.
Rapid Reviews
- Quickly summarise evidence for decision-making, often under time constraints.
- Applies "Systematic Review" methodology within a time-constraint setting.
Systematic Reviews
- Provides a high-quality, unbiased summary of research on a specific question.
- Compares, evaluates, and synthesises evidence in a search for the effect of an intervention.
- The most commonly referred to type of evidence synthesis.
- Sometimes confused as a blanket term for other types of reviews.
Umbrella Reviews (Review of Reviews)
- Synthesises evidence from multiple systematic reviews on a broader topic.
- 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, synthesise, and summarise results.
- May be conducted independently or as part of a systematic review.
