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DOH321 Research Skills Guide: Appraise the Evidence

Evaluation & Critical Appraisal Introduction

Once you have asked the clinical question and searched for evidence, you need to evaluate and critically appraise the evidence you have ""located in order to:

  • cut down on information overload
  • disregard studies which have scientific flaws
  • find studies relevant to your situation.


There are a number of tools you can use to help you evaluate evidence or information. One of these is the CRAP tool. The CRAP tool is a set of criteria; Currency, Reliability, Authority and Purpose, that you can apply to any information resource. The CRAP tool is discussed in more detail on the Evaluating Information page.


A tool specifically designed to help you when evaluating evidence based practice research is CASP (Critical Appraisal Skills Programme). For more information on CASP see the CASP page in this guide.