Skip to Main Content

Evidence Based Practice for Allied Health Sciences: Step 4: Appraise

Appraising and Evaluating Information

What Am I Looking At?

Often, you can use the same procedures you used to create your research question when analyzing a study.  Is the study answering a background question or a foreground question?  Can you identify the PICO or PICOT of the study?  When were the outcomes of the study determined?

Should I Use This Resource?

When evaluating a source to determine if you should include it in your analysis, ask yourself the following questions:

  • Does the study/evidence address my question?
  • Is the source reliable?
  • Are the results valid?
  • Is the methodology sound?
  • Does the evidence apply to my patient or population?

Validity vs Reliability

When you examine a study, you will want to determine if it is valid and reliable.  Ideally, the studies you use should be both valid and reliable.

  • Validity - the ability to measure what is supposed to or is intended to be measured - provides credible results
    • If I measure hand strength, can I draw a conclusion about intelligence?
  • Reliability - the ability to measure what you want to measure on subsequent experiences
    • If I take a personality test twice in a row, will the results be the same?  If the test is reliable, they will!

The Diagram:

  • Unreliable and Invalid - Does not measure what I want, and the results are different when I repeat the test
  • Unreliable but Valid - The results are inconsistent and the test does not seem to measure what I thought it would - I cannot draw a conclusion based off of my data
  • Reliable but Invalid - The results are consistent when the test is repeated, but I cannot draw the conclusion I thought I could
  • Reliable and Valid - The test measures what it should, and the results are repeatable (and consistent with other measurements)

Image from



Critical Appraisal Worksheets

There are plenty of checklists out there to critically appraise medical research: 

How to Appraise Medical Literature

Check out how to appraise literature and all types of studies using this playlist from Dr. Terry Shaneyfelt 

How to Read Medical Literature