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Critical appraisal

What is critical appraisal?

Critical appraisal is the process of carefully and systematically examining research to judge its trustworthiness, its value and relevance in a particular context (Burls, 2009).

Why do we need to critically appraise the literature?

We do this to:

  • Weigh up the evidence for usefulness
  • Assess benefits and strengths for research against flaws and weaknesses
  • Assess the research process and results: Are the findings reliable? What do the results mean in the context of the decision we are making?

(Adapted from the Curtin University Systematic Reviews LibGuide.)


Questions to ask when critically appraising

1. What is the research question and why was the study needed? (Greenhalgh, 2010)

2. Does the study have new findings? Is the work original and important?

3. Does the research question address the following components:

  • The group or population of patients
  • The intervention or therapy
  • The outcome

4. Did the authors use the right type of study in relation to the research question? (Young, 2009) For example:

  • Therapy questions > Randomised controlled trials
  • Experiences > Qualitative studies

5. Did the chosen study design minimise bias? For example, did the study use a randomised controlled trial or a systematice review?

6. Was the study designed in line with the original protocol i.e. stated methods? For example, were there changes to the inclusion or exclusion criteria?

7. Has the study's hypothesis (expected outcome) been tested?

8. Is the analysis of the data accurate?

9. Are the conclusions based on the data and analysis? (Taylor & Health Sciences Writing Centre University of Toronto, n.d.)

10. Does the study contribute to the understanding of the problem being investigated? What are the strengths and limitations of the study? Are the findings of the study useful for clinical practice?


Burls, A. (2009). What is critical appraisal? Retrieved from:

Greenhalgh, T. (2010). How to read a paper: The basics of evidence-based medicine. Chichester, U.K.: Wiley-Blackwell.

Taylor, D., & Health Sciences Writing Centre University of Toronto. (n.d.). The literature review: A few tips on conducting it. Retrieved from:

Young, J. M. (2009). How to critically appraise an article. Nature Clinical Practice Gastroenterology and Hepatology, 6(2), 82. doi:10.1038/ncpgasthep1331

Critical appraisal websites

  • Center for Evidence Based Medicine (CEBM)
    The Centre for Evidence-Based Medicine in Oxford (UK) provides tools to develop, teach and promote evidence-based health care. Their site provides useful tools and downloads for the critical appraisal of medical evidence. Example appraisal sheets are provided together with several helpful examples.
  • Critical Appraisal Skills Programme (CASP)
    The Critical Appraisal Skills Programme (CASP) helps people to find and interpret the best available evidence from health research.
  • Joanna Briggs Critical Appraisal Tools
    Provides access to critical appraisal tools for different types of studies including systematic reviews and RCTs.



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Subjects: Faculty of Medical Sciences