Critical appraisal tools to make sense of evidence

A Summary of

Public Health Resource Unit (2006). The Critical Skills Appraisal Programme: making sense of evidence. Public Health Resource Unit, England. Retrieved from:


The Critical Appraisal Skills Programme (CASP) helped to develop an evidence-based approach in health and social care, working with local, national and international groups. CASP aims to help individuals develop skills to find and make sense of research evidence, helping them to apply evidence in practice.

The Critical Appraisal Skills Programme (CASP) tools were developed to teach people how to critically appraise different types of evidence. There are seven checklists specifically designed to appraise:

  1. Systematic Reviews
  2. Randomized Controlled Trials (RCTs)
  3. Qualitative Research
  4. Economic Evaluation Studies
  5. Cohort Studies
  6. Case Control Studies
  7. Diagnostic Test Studies

All critical appraisal tools consist of three sections to assess internal validity, the results and the relevance to practice.

The CASP appraisal tools were developed from guides produced by the Evidence Based Medicine Working Group published in the Journal of the American Medical Association.

Access the Tool

Format of the Tool


Not specified


Not specified


Not Specified

Using the Tool

Time for Participation/Completion

10 to 30 minutes

Depending on the length of the study, it could take an individual up to 30 minutes to use a CASP tool.

Additional Resources and/or Skills Needed for Implementation

The CASP tools require users to be familiar with the study type to be able to appraise the study.

Steps for Using Method/Tool

Each Critical Appraisal Skills Programme (CASP) appraisal tool asks three broad questions:

  • Is the study valid?
  • What are the results?
  • Will the results help locally?

Each of the seven appraisal tools includes 10–12 questions. The first two questions are screening questions; if the answer is yes to both, it is worth proceeding with the remaining questions to assess the study. Prompts are given with each question to remind the user why the question is important.

There are seven critical appraisal tools to assess:

  1. Systematic Reviews
  2. Randomized Controlled Trials (RCTs)
  3. Qualitative Research
  4. Economic Evaluation Studies
  5. Cohort Studies
  6. Case Control Studies
  7. Diagnostic Test Studies

Who is involved

Any individual interested in learning how to critically appraise research evidence could use the CASP tools.

Conditions for Use

Not specified

Evaluation of the Tool


Has been evaluated.

The tools were pilot tested in workshops, including feedback and review of materials, using successively broader audiences. Thus the CASP tools are suitable for a wide target audience in service administration and health care delivery.


Not applicable


Not applicable

Methodological Rating

Not applicable

Development of the Tool


The Critical Appraisal Skills Programme

Method of Development

The CASP checklists were developed using a four-stage process:

  • A multidisciplinary working group and CASP secretariat drafted written materials.
  • The working group tested the critical appraisal tool and modified it as needed.
  • The tool was piloted with a knowledgeable audience and further modified.
  • Non-expert health professionals used the tool.

The members of the multidisciplinary working groups had backgrounds in public health, epidemiology or evidence-based practice.

Release Date


Contact Person/Source

Amanda Burls
Critical Appraisal Skills Programme (CASP)

These summaries are written by the NCCMT to condense and to provide an overview of the resources listed in the Registry of Methods and Tools and to give suggestions for their use in a public health context. For more information on individual methods and tools included in the review, please consult the authors/developers of the original resources.

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