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Systematic Reviews & Evidence Based Reviews

An overview of systematic reviews and other evidence-based reviews.

What is a systematic review?

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 They seek to identify and synthesize all research on a particular topic, including published and unpublished studies.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.

Types of reviews




Cornell University Library's Review Methodology Decision Tree, "What Type of Review Is Right for You?" [link to a PDF document], from their Evidence Synthesis Guide.


Characteristics of reviews

Characteristics of reviews to consider:

Feature Narrative Scoping Rapid Systematized Systematic
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. 

Sample timeline

Activity 1 2 3 4 5 6 7 8 9 10 11 12
Preparation of protocol                    
Searches for published & unpublished studies                        
Pilot test for eligibility criteria                        
Inclusion assessments                        
Pilot test of "Risk of Bias" assessment                        
Validity assessments                        
Pilot test of data collection                        
Data collection                        
Data entry                        
Follow up of missing information                        
Preparation of review report                        
Keeping the review up to date (12 months & on)                        

Timeline predicter