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Occupational Therapy Assistant: Evidence Appraisal

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What is Critical Appraisal?

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.


These tools will help you to interpret the clinical and statistical significance of data reported in clinical research.

How To Read a Paper

Did you know that you can check out a copy of Trisha Greenhalgh's How to Read a Paper at the MEC Library?

Cover Art

How to Read a Paper: The Basics of Evidence-based Medicine

Call Number:
R118.6 .G74 2010

ISBN: 1405139765

Why read papers at all?
Searching the literature
Getting your bearings: what is this paper about?
Assessing methodological quality
Statistics for the non-statistician
Papers that report drug trials
Papers that report diagnostic or screening tests
Papers that summarise other papers (systematic reviews and meta-analyses)
Papers that tell you what to do (guidelines)
Papers that tell you what things cost (economic analyses)
Papers that go beyond numbers (qualitative research)
Papers that report questionnaire research
Getting evidence into practice.


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.