The Evidence Pyramid is a visual representation of the types of publications that constitue the nursing/medical literature. Use the pyramid as a guide to help you focus on the best available evidence for supporting your PICOT question.

Level I: Systematic Reviews or Meta-analyses of all relevant Randomized Controlled Trials or clinical practice guidelines based on systematic reviews of RCTs or three or more RCTs of good quality that have similar results.

Level II: Evidence obtained from at least one well-designed RCT

Level III: Evidence obtained from well-designed controlled trials without randomization

Level IV: Evidence from well-designed cohort or case-controlled studies

Level V: Evidence from case series and case reports on the treatment of individual patients

Level VI: Evidence obtained from experts that lack strong methodological quality               

Graphic: University of Michigan Library

Not all evidence is created equal.  When searching the literature keep in mind that the strongest evidence (Systematic Reviews, Randomized Controlled Trials and Meta-analyses) is indexed with less frequency than studies with weaker evidence.  It can take several or more years to conduct a rigorous systematic review or meta-analysis before being published in a peer-reviewed journal.              

The difference between quantitative and qualitative study designs is in the type of data they collect. Quantitative data is usually numerical, while qualitative data is more descriptive. Both types of study have value, and they often work well together to provide a broader view of your subject.

Wondering how to conduct a systematic review? This explainer video from The Evidence Synthesis Academy at Brown University walks you through the basic steps.

• Creator:   American Journal of Nursing
• Updated:   8/25/2022
• Contains:  6 items  

This series on the systematic review from the Joanna Briggs Institute, an international collaborative supporting evidence-based practice in nursing, medicine, and allied health fields, shows nurses how to conduct a systematic review—one step at a time.

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