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Systematic Reviews & Evidence Synthesis Methods

A detailed, step-by-step guide to the first several stages of an evidence synthesis review.

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About this guide

This research guide provides an overview of the evidence synthesis process, guidance documents for conducting evidence synthesis projects, and links to resources to help you conduct a comprehensive and systematic search of the scholarly literature. Navigate the guide using the tabs on the left.

"Evidence synthesis" refers to rigorous, well-documented methods of identifying, selecting, and combining results from multiple studies. These projects are conducted by teams and follow specific methodologies to minimize bias and maximize reproducibility. A systematic review is a type of evidence synthesis. We use the term evidence synthesis to better reflect the breadth of methodologies that we support, including systematic reviews, scoping reviews, evidence gap maps, umbrella reviews, meta-analyses and others.

Note: Librarians at UC Irvine Libraries have supported systematic reviews and related methodologies in STEM fields for several years. As our service has evolved, we have added capacity to support these reviews in the Social Sciences as well.

Systematic review OR literature review conducted systematically?

There are many types of literature reviews. Before beginning a systematic review, consider whether it is the best type of review for your question, goals, and resources. The table below compares systematic reviews, scoping reviews, and systematized reviews (narrative literature reviews employing some, but not all elements of a systematic review) to help you decide which is best for you. See the Types of Evidence Synthesis page for a more in-depth overview at types of reviews.

Comparison of systematic, scoping, and systematized reviews.
  Systematic Review Scoping Review Systematized Literature Review
Purpose Publication Publication Assignment, thesis, justification for primary research, or (possibly) publication
Protocol Required Required Optional
Research Question Focused Broad Broad or Focused
Inclusion / Exclusion Criteria Focused Broad Broad or Focused
Critical Appraisal of Evidence Required Optional Optional
Research Team Minimum 3+, including content expert, searching expert, project manager, & statistical expert (for meta-analyses) Minimum of 2 (ideally 3+) Usually 1 or 2 (one may be an advisor)
Average Time to Complete 12-18 months, sometimes longer 12-18 months, sometimes longer 2-6 months