What is a Systematic Review / Evidence Synthesis?
Evidence synthesis is the process of bringing together information from a variety of sources and disciplines in order to further our understanding on a specific topic. A common form of evidence synthesis is the systematic review, or a study of studies.
Reviews and syntheses follow a rigorous, reproducible methodology, reducing as much bias as possible. They seek to identify and synthesize all research on a particular topic, including published and unpublished studies. Because of their depth and intensity, evidence syntheses and systematic reviews require a multi-person research team.
Characteristics of reviews to consider:
|Question||Broad in scope||Exploratory||Well-defined and focused||Well-defined and focused||Well-defined and focused|
|Search||Not specified; potentially biased||Completeness of searching determined by time constraints||Completeness of searching determined by time constraints||May or may not be included in publication||Exhaustive, comprehensive, and reproducible|
|Appraisal||None||None||Time-limited assessment||May or may not include||Yes, important part of review|
|Synthesis||Narrative||Typically tabular with some narrative||Typically narrative and tabular||Typically narrative with tabular accompaniment||Typically narrative and tabular|
|Team||No||Yes||Yes||May or may not have a team||Yes|
|Meta-analysis of results||No||No||No||No||Sometimes|
|Time||<3 months||4-12 months||<4 months||8-12 months||12-18 months|
Adapted from Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26(2), 91-108.
|Preparation of protocol|
|Searches for published & unpublished studies|
|Pilot test for eligibility criteria|
|Pilot test of "Risk of Bias" assessment|
|Pilot test of data collection|
|Follow up of missing information|
|Preparation of review report|
|Keeping the review up to date (12 months & on)|