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Evidence-Based Practice: Rating Evidence

An overview of evidence-based practice (EBP) and EBP resources at Stimson Library.

Assigning Levels of Evidence

There are many different approaches to rating evidence. See this handy comparison chart for some of the best-known rating systems. The tables below describe rating/grading guidelines frequently referenced at the Academy of Health Sciences.

Rating System for the Hierarchy of Evidence

Evidence Rating Evaluation Criteria

Level I

Evidence from a systematic review or meta-analysis of all relevant randomized controlled trials (RCTs), or evidence-based clinical practice guidelines based on systematic reviews of RCTs
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 case-control and cohort studies
Level V Evidence from systematic reviews of descriptive and qualitative studies
Level VI Evidence from a single descriptive or qualitative study
Level VII Evidence from the opinion of authorities and/or reports of expert committees

From: Melnyk, Bernadette Mazurek, and Ellen Fineout-Overholt. Evidence-Based Practice in Nursing & Healthcare: A Guide to Best Practice.

Johns Hopkins Nursing Quality of Evidence Appraisal

Grade Nomenclature Definition for Research Evidence Definition for Non-Research Evidence
A High Consistent results, sufficient sample size, adequate control, and definitive conclusions; consistent recommendations based on extensive literature review that includes thoughtful reference to scientific evidence Expertise is clearly evident
B Good Reasonably consistent results, sufficient sample size, some control, and fairly definitive conclusions; reasonably consistent recommendations based on fairly comprehensive literature review that includes some reference to scientific evidence Expertise appears to be credible
C Low/Major Flaw Little evidence with inconsistent results, insufficient sample size, conclusions cannot be drawn Expertise is not discernable or is dubious

From: Newhouse, Robin Purdy. Johns Hopkins Nursing Evidence-Based Practice Model and Guidelines, p. 207.

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