The third step in the Evidence-Based Practice process is to critically appraise the research. This means that you wnat to take an in-depth look at the research available on your topic and determine what research responds best to your research question and if it adequately supports making a change.
When appraising research, keep in mind the following three criteria:
Look for 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.
Look for 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).
Look for 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.
For an article to be strong evidence, it has to fulfil the requirements of all three criteria.
Source: Critical Appraisal. Bandolier Journal.
Tools to help you to interpret the clinical and statistical significance of data that is reported in research:
Are you having trouble accessing articles? Consult the “Accessing Articles” tab under “Conducting Research” on the left side of this guide for information on how to access articles.