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Critical appraisal

Guidelines for the critical appraisal of a paper

  • Who wrote the paper?
  • Do they or the institution have a proven academic record?
  • Is the paper interesting and relevant?


  • Did the study introduction address the relevant points?
  • Was the study original?
  • Were the aims clearly stated?


  • Was an appropriate group of subjects studies?
    • How were subjects recruited?
    • What were the inclusion criteria?
    • What were the exclusion criteria?
  • Was the sample size justified?
    • Was a power calculation performed?
  • Was the study design appropriate?
    • Review - systematic or meta-analysis
    • Drug treatment - randomised controlled trail
    • Prognosis - cohort study
    • Causation - case - control study
  • Were the study groups comparable?
    • Demographics, baseline criteria etc
  • Was the assignment of patients to treatments randomised?
    • How was the randomisation performed
  • Were the groups treated equally other than for the experimental intervention?
  • Were the outcome measures stated and relevant?
  • Were measurements valid and reliable?
  • Were patients and healthcare workers 'blinded' to the treatment given?
  • Were all patients entered into the study properly accounted for?
  • Is there any missing data?
  • Were side effects and adverse outcome documented?
  • Was the duration and completeness of follow up appropriate?


  • Were the statistical methods described?
    • Does the tests chosen reflect the type of date
    • Parametric versus parametric tests
  • Were analyses performed on an intention to treat basis?
  • Was systematic bias avoided or minimized?


  • How large was the treatment effect?
  • How precise was the estimate of the treatment effect?


  • Were the aims of the study fulfilled?
  • Were the sources of error discussed?
  • Are the relevant findings justified?
  • Are the conclusions of the paper justified?
  • Are likely treatment benefits worth the potential harm or costs?
  • What is the impact of the paper?
  • Can the results be generalised to other populations?
  • What do you think of the paper?


Greenhalgh T.  The Medline database.  Br Med J 1997;  315:  180-183

Greenhalgh T.  Getting your bearings (deciding what the paper is about).  Br Med J 1997;  315:  243-246

Greenhalgh T.  Assessing the methodological quality of published papers.  Br Med J 1997;  315:  305-308

Greenhalgh T.  Statistics for the non-statistician I:  Different types of data need different statistical tests:  Br Med J 1997;  315:  364-366.

Greenhalgh T.  Statistics for the non-statistician II:  Significant relations and their pitfalls. Br Med J;  1997:  315;  422-425

Greenhalgh T.  Papers that report drug trials.  Br Med J 1997;  315:  480-483

Greenhalgh T.  Papers that report diagnostic or screening tests.  Br Med J 1997;  315:  540-543.

Greenhalgh T.  Papers that tell you what things cost (economic analysis).  Br Med J 1997;  315:  596-599.

Greenhalgh T.  Papers that summarize other papers (systematic reviews and meta-analyses).  Br Med J 1997;  315:  672-675.

Greenhalgh T.  Papers that beyond numbers (qualitative research).  Br Med J 1997;  315:  740-743.

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Last updated: 08 January 2012

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