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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

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, Gallagher-Ford & Fineout-Overholt.  Implementing the Evidence-Based Practice (EBP) Competencies in Healthcare.

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: Dang & Dearholt.  Johns Hopkins Nursing Evidence-Based Practice Model and Guidelines, p. 207.

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