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Systematic Reviews: Introduction

Learn about conducting systematic reviews


A systematic review is a review of all published and unpublished evidence on a specific topic, using an explicit game plan that can be reproduced by another researcher or team.

From the Cochrane Handbook for Systematic Reviews of Interventions (2019):

A systematic review attempts to collate all the empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question. It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made.

Systematic reviews are important, often rewarding and, at times, exciting research projects. They offer the opportunity for authors to make authoritative statements about the extent of human knowledge in important areas and to identify priorities for further research. They sometimes cover issues high on the political agenda and receive attention from the media.

Conducting research with these impacts is not without its challenges, however, and completing a high-quality systematic review is often demanding and time-consuming. 

Systematic Review Characteristics

Systematic reviews are a powerful tool for evidence-based public health (EBPH) because they provide:

  • a clearly stated set of objectives with pre-defined eligibility criteria for studies
  • an explicit, reproducible methodology
  • a systematic search that attempts to identify all studies that would meet the eligibility criteria
  • an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias
  • a systematic presentation, and synthesis, of the characteristics and findings of the included studies

in order to meet the following objectives: 

  1. address a specific (well focused, relevant) question
  2. collate the results of the research in a systematic way
  3. appraise the quality of the research in the light of the research question
  4. make the knowledge base more accessible
  5. identify gaps; to place new proposals in the context of existing knowledge
  6. propose a future research agenda; to make recommendations

From Cochrane Handbook for Systematic Reviews of Interventions (2019) and Torgerson (2003).

An Introduction to Systematic Reviews: Yale School of Medicine (7:39)

This video is the first in an 11 part Systematic Searches video tutorial series from the Harvey Cushing/John Hay Whitney Medical Library. 

What are Systematic Reviews? Cochrane (3:23)

Levels of Scientific Evidence