Some reviews require a critical appraisal for each study that makes it through the screening process. This involves a risk of bias assessment and/or a quality assessment. The goal of these reviews is not just to find all of the studies, but to determine their methodological rigor, and therefore, their credibility.
"Critical appraisal is the balanced assessment of a piece of research, looking for its strengths and weaknesses and them coming to a balanced judgement about its trustworthiness and its suitability for use in a particular context." 1
It's important to consider the impact that poorly designed studies could have on your findings and to rule out inaccurate or biased work.
Selection of a valid critical appraisal tool, testing the tool with several of the selected studies, and involving two or more reviewers in the appraisal are good practices to follow.
1. Purssell E, McCrae N. How to Perform a Systematic Literature Review: A Guide for Healthcare Researchers, Practitioners and Students. 1st ed. Springer; 2020.
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