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Critical appraisal

Critical appraisal overview

Before using studies in your review, you need to critically appraise them for quality and risk of bias.

Move through the slide deck below to learn more about critical appraisal. Alternatively, download the PDF document at the bottom of this box.

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Critical appraisal tools

Use a formal Critical Appraisal Tool ("CAT") to assess your papers. The tool must be applied without adaptation to the appropriate study design.

The application of a CAT ('CASP')

The Cochrane Common Mental Disorders group have produced 7 videos demonstrating the application of the CASP checklist to different study designs.

Guidelines and standards

'Specify the methods used to assess risk of bias in the included studies, including details of the tool(s) used, how many reviewers assessed each study and whether they worked independently, and, if applicable, details of automation tools used in the process.' - PRISMA 2020 Explanation and Elaboration, p. 11

Other standards

Hierarchy of evidence variations

Many hierarchies have been developed to show the different levels of evidence, and to 'rank' different study designs. See some common ones below:

Further resources