Critical appraisal is the process of carefully and systematically examining research to judge its trustworthiness, its value, and its relevance in a particular context.
Information, calculators, checklists, and tools to help you critically appraise research articles are provided on this page.
Did you know that you can check out a copy of Trisha Greenhalgh's How to Read a Paper at the MEC Library?
When appraising research, keep the following three criteria in mind:
Trials that are randomised and double blind, to avoid selection and observer bias, and where we know what happened to most of the subjects in the trial.
Trials that mimic clinical practice, or could be used in clinical practice, and with outcomes that make sense. For instance, in chronic disorders we want long-term, not short-term trials. We are [also] ... interested in outcomes that are large, useful, and statistically very significant (p < 0.01, a 1 in 100 chance of being wrong).
Trials (or collections of trials) that have large numbers of patients, to avoid being wrong because of the random play of chance. For instance, to be sure that a number needed to treat (NNT) of 2.5 is really between 2 and 3, we need results from about 500 patients. If that NNT is above 5, we need data from thousands of patients.
These are the criteria on which we should judge evidence. For it to be strong evidence, it has to fulfill the requirements of all three criteria."
Source: Critical Appraisal. Bandolier.
Dr. Trisha Greenhalgh's clearly written papers (links below) discuss how to critically appraise the medical literature.
These articles appeared originally in the British Journal of Medicine and were later produced as a book: How to Read a Paper (see more information about the book on your left).