Critical appraisal is the process of carefully and systematically assessing the outcome of scientific research (evidence) to judge its trustworthiness, value and relevance in a particular context.
It involves looking at the way a study is conducted and examines factors such as internal validity, generalizability and relevance. Critical appraisal is intended to enhance the healthcare professional's skill to determine whether the research evidence is true (free of bias) and relevant to their patients.
While the average clinician may do little actual critical appraisal of primary sources, ALL clinicians must be educated in the process so that their application of information derived from an ostensibly "evidence-based" approach to medicine will be well-informed, and not simply blind application of an "EBM rule" rather than blind application of what the local experts say.
Trying to make sense of health research? is an online tool that guides you through a series of questions to help you to review and interpret a published health research paper, http://www.understandinghealthresearch.org/
The critical appraisal tool you select is driven by the type of material you are appraising. As a general guide, the following questions could be asked as a minimum:
1. What is the research question and why was the study needed?
2. Does the study have new findings? Is the work original and important?
3. Does the research question address the following components:
4. Did the authors use the right type of study in relation to the research question? For example:
5. Did the chosen study design minimise bias? For example, did the study use a randomised controlled trial or a systematic 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?
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?
Ideally, you will assess the type of information you are evaluating, and follow the process with an applicable tool. The International Centre for Allied Health Evidence provides a comprehensive selection of tools for,
Cochrane Handbook for Systematic Reviews of Interventions by 
Nursing research: methods and critical appraisal for evidence-based practice by 
Understanding the Australian health care system by 
Comprehensive Systematic Review for Advanced Practice Nursing by 
How to do a systematic literature review in nursing: a step-by-step guide by 
Systematic Reviews to Support Evidence-Based Medicine by Please complete the Book Request Form to borrow a book from a QH Library.
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