Once you have searched for information, you will need to critically appraise the studies you have found. This is a really important process because it ensures that studies with scientific flaws are disregarded, and the ones you include are relevant to your research question.
When evaluating primary research (research which hasn't been pre-appraised or filtered by others), you need to make sure the evidence you are including in your review is scientifically rigorous. The main questions to address are:
For a more detailed look at Critical Appraisal, head to the Systematic Review Guide - Critical Appraisal and the Evidence-Based Practic Guide - Appraise.
Critical appraisal of health articles can be very time consuming. Sometimes you just need to quickly decide on the trustworthiness and value of a paper. Here are some things to consider:
R - Recruitment – were the subjects chosen in the study representative of the target population? Were there enough subjects to make the study valid?
A - Allocation – was the trial randomised?
M - Maintenance – Was the status of the control group and study group maintained throughout the trial? Were they treated the same way apart from the intervention?
M - Measurement (Blinding, Objective measures) – were the outcomes measured objectively and the subjects blinded to the intervention? Was bias eliminated as much as possible?
Another great tool for quick appraisal of health articles is from the Medical Research Council in the UK. Understanding Health Research takes you through a series of questions about a particular article, highlighting the good points and possible problem areas. You can print off a summary at the end of your checklist.
See the next box below for some more detailed appraisal tools in the health sciences.
Salisbury, J., Glasziou, P., & Del Mar, C. (2007). Evidence-based practice workbook: Bridging the gap between health care research and practice (2nd ed.). Oxford: Blackwell/BMJ Books.
Fortunately, there have been some great checklist tools developed for different types of studies. Here are some examples:
Critical appraisal tools from the NHS in Scotland links interactively to all sorts of resources on how to identify the study type and build your critical appraisal skills, as well as to tools themselves.
Introduction to Critical Appraisal - A 4:11 min. YouTube video (actually it's more like a podcast) which looks at the background to critical appraisal, what it is, and why we do it.
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