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Evidence-Based Practice in Health

This guide includes a tutorial about Evidence-Based Practice (EBP) in Health, a Reference Shelf of supporting eBooks, and a Toolkit of online sources of evidence.

Critical Appraisal Process

Critical appraisal is an integral step in Evidence Based Practice.  Critical appraisal aims to identify methodological flaws in research and provide consumers of research with the opportunity to make informed decisions about the quality of research evidence.

Critical appraisal is a systematic process of analysing research to assess methods, validity and usefulness.

The key questions in critical appraisal are:

Why was the study done?

  • A clearly focused question should address population, intervention and outcomes.

What type of study was done?

  • The study design must match the question asked. Intervention questions are best answered with randomised controlled trials.

What are the study characteristics?

  • Use the PICO question format to help you answer this question:
P Patient/Population? How were participants recruited/selected?
I What intervention/test is being studied?
C Is the intervention/test being compared to no intervention, placebo, another treatment?
O What outcomes are being assessed - objective/subjective/surrogate? Secondary outcomes?     


What was done to address bias?

  • Was the assignment of patients to treatments randomised?
  • Were patients, health workers and study personnel ‘blind’ to treatment allocation? 
  • Were all of the patients who entered the trial properly accounted for at its conclusion? Look for follow-up tables and whether patients were analysed in the groups to which they were randomised. 
  • Were the groups similar at the start of the study?
  • Aside from the experimental intervention, were the groups treated equally?

What are the results and are the results valid?

  • Are the outcome measures relevant?
  • How large was the treatment effect?How precise was the estimate of the treatment effect?
  • Look for confidence limits and p values.

What conclusions can you make?

  • Are the results generalisable, that is, can the results be applied to my patients?  Were all clinically important outcomes considered? Are the benefits worth the harms and costs?
  • Are the results relevant to my situation? Patient population / similar definitions/protocols / health system similarites.1

Critical Appraisal Tools (CATs)

Checklists and Worksheets

These can be downloaded and used to assess the applicability, reliability and validity of published research.

Critical Appraisal Skills Programme: CASP Critical Appraisal Checklists.

Centre for Evidence-Based Medicine: CEBM Criticial Appraisal Worksheets.

University of South Australia list of Critical Appraisal Tools organised by research method.


Centre for Evidence-Based Medince: CEBM Statistics Calculator.

Number Needed to Treat (NNT) Calculator.

Article Synopses

You do not always need to do critical appraisal yourself.  These quality filtered resources provide structured abstracts and expert commentary of individual studies.


1. Voutier, C. (2013). Critical appraisal. Evidence Direct: A Service of the RMH Health Sciences Library.  Retrieved 4 July 2014 from: