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NSG 3930: Nursing Research and Evidence Based Practice: Levels of Evidence

Recommended resources for students in Nursing Research

Levels of Evidence

Information from "Evidence-based practice in nursing & healthcare: a guide to best practice" by Bernadette M. Melnyk and Ellen Fineout-Overholt. 2005, page 10.

Level I: Evidence from a systematic review or meta-anlysis of all relevant randomized controlled trials (RCT), from evidence-based clinical practice guidelines that are based on systematic reviews of RCTs, or from 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 case-control or cohort studies

Level V: Evidence from systematic reviews of descriptive and qualitative studies(often referred to as integrative or mixed-method)

Level VI: Evidence from a single descriptive or qualitative study

Level VII: Evidence from the opinion of authorities and/or reports of expert committees

Joanna Briggs Institute (

The Joanna Briggs Institute  (

The JBI regards evidence-based health care as a cyclical process. Global health care needs, as identified by clinicians or patients/consumers, are addressed through the generation of research evidence that is effective, but also feasible, appropriate and meaningful to specific populations, cultures and settings. This evidence is collated and the results are appraised, synthesised and transferred to service delivery settings and health professionals who utilise it and evaluate its impact on health outcomes, health systems and professional practice.

The JBI Levels of Evidence:

The JBI Grades of Recommendation: