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NURS 2300 - Nursing Concepts II

Hierarchy of Evidence

Different types of research present different kinds of evidence. Think of evidence as being arranged in a hierarchy or pyramid. Studies at the top of the evidence pyramid have a higher value but fewer are created.

Study types beginning with the most valuable 1) clinical guidlines, systematic review, meta-analysis, 2) randomized control trial, 3) cohort study, 4) case control studies, 5) case series or case reports, 6) animal & laboratory studies

Matching Questions to Evidence

The following table tells you what types of evidence you should look for depending on the question type you are researching. For each question type, the most reliable evidence is listed first, followed by less reliable evidence.

Question Type

Best Evidence
Therapy (Treatment) randomized control trial
Prevention randomized control trial >> cohort study
Diagnosis prospective, blind comparison to a gold standard
Prognosis (Forecast) cohort study >> case control study >> case series study
Etiology/Harm (Cause) randomized control trial >> cohort study >> case control study >> case series study