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Introduction to systematic reviews

About this guide

This guide focuses on the searching aspect of the systematic review process. It contains guidance on formulating the review question, developing the search protocol, the specific search techniques required by a systematic review, database searching, and grey literature. It also provides guidance on reference management software, which is important for organising the large volume of references which the searches will generate, critical appraisal tools, and reporting and synthesising results.

Use the left hand blue menu options to navigate through this guide which follow a step-by-step process.

What is a systematic review?


High quality systematic reviews aim to:

  • Identify all relevant published and unpublished evidence on the subject of the review
  • Select studies for inclusion
  • Assess the quality of each study
  • Synthesis the findings in an unbiased way
  • Present a balanced summary of the findings

Hemingway, P. & Brereton, N. (2009). What is a systematic review? (2nd ed.). What is...? series.

Difference between a systematic review and a literature review

It is easy to confuse systematic reviews with literature reviews done in a systematic way. This table shows the main differences between systematic reviews and literature reviews.

Systematic vs Literature Table

Kysh, L. (2013). Difference between a systematic review and a literature review. Figshare. 

What type of review is right for you?

The Review Methodology Decision Making Tree (link to PDF) produced by Cornell University Library can assist you with deciding on the type of review that is right for you:

Identifying the right type of review for your study flowchart

"Review Methodologies Decision Tree" by Cornell University Library is licensed under CC BY 4.0.

The stages of a systematic review

A systematic review typically follows these steps:

  • Defining the research question and the inclusion and exclusion criteria (the search protocol)
  • Identifying studies (searching the databases)
  • Screening and selecting studies for inclusion
  • Appraising the relevance and quality of each study
  • Analysing and synthesising the data from the studies so the research questions can be answered (meta-analysis/meta-synthesis, etc.)
  • Addressing reporting biases
  • Presenting results
  • Interpreting results and drawing conclusions

From UCL's Stages in a systematic review guide

This short video, by The Evidence Synthesis Academy at Brown University, provides a useful overview of the basic steps in undertaking a systematic review.