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Evidence synthesis

Appraisal 

The critical appraisal of information resources, such as studies, you have collected is a key step in assessing the quality of the evidence that makes up your review. The process assesses the quality, reliability and relevance of studies included in a review, ensuring that the evidence used in your review is robust and trustworthy.

The elements used in appraisal may differ across different areas of research. The criteria for appraisal will vary depending on the type of study or information resource being assessed. Empirical studies may be evaluated for methodological rigour and risk of bias. Other information resources, such as policy documents or conference papers, may require different appraisal approaches.

Instruction

At least two reviewers should complete the appraisal process to minimise bias.

Appraisal tools

A range of appraisal tools exist to assess different types of evidence. The choice of tool and appraisal process should be explicitly documented in the review protocol to ensure transparency and reproducibility.

Common appraisal tools that provide structured frameworks for critical appraisal across various disciplines are:

  • CASP (Critical Appraisal Skills Programme)
    Provides structured checklists with clear prompts and questions to guide the appraisal process, helping users assess the quality and relevance of research in a systematic way. Useful for a variety of study designs, including qualitative research, randomised controlled trials (RCTs), and cohort studies.
     
  • JBI (Joanna Briggs Institute)
    Offers detailed critical appraisal checklists with explanatory guidance, supporting a structured and consistent approach to assessing research quality across a wide range of methodologies. Useful for appraising a variety of study designs, including observational studies, systematic reviews, qualitative research, and text or opinion-based papers.
     
  • CEBM (Centre for Evidence-Based Medicine)
    Provide critical appraisal work sheets to help with appraising the reliability, importance and applicability of clinical evidence. Useful for systematic reviews, diagnostics, prognosis, randomised controlled trials (RCTs) and qualitative studies.
     
  • Campbell Collaboration
    Provides detailed requirements and guidelines for producing Campbell systematic review that address critical appraisal.  

Literature review modules

For further information and instructions on the screening stage of a literature review please explore our Module 6: Screening, Synthesis and Dissemination.


Further resources

If you are interesting in further information on this stage of a review, check out the following resources: