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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 https://commons.wikimedia.org/wiki/File:Reliability_and_validity.svg

 

 

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

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