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Evidence-Based Practice: Nursing

This is an evidence base pyramid.  It is often used as a reference to illustrate evidence based literature.  Before starting a literature search, use this illustration as a reference on where to begin.  Beginning at the top will give you the highest quality of literature.

Filter information is information that has been filtered to include studies that are of the highest quality.  These resources have been evaluated for their quality and are recommended for practice  As you ascend the pyramid you will see that amount of studies begin to decrease, but the quality of the studies increase.  These studies include:

  • Critically-appraised individual articles
  • Critically-appraised topics
  • Systematic Reviews 

Unfiltered information is made up of primary or original research studies.  This tier has information that covers a much broader range of clinical issues, however you may not find studies that are of the highest quality.  These studies include:

  • Case Control Studies
  • Cohort Studies
  • Randomized Control Trials (RCT)

Evidence pyramid


Type of Question Type of Study
Therapy/Treatment Double-blind, randomized control trial (RCT), systematic reviews, meta analysis 
Diagnosis Controlled trials, systematic reviews, meta analysis
Prognosis Cohort studies, case control, case series
Harm/Etiology Cohort Studies, case control, case series
Prevention RCT, cohort studies
Quality Improvement RCT