Table 1.

Hierarchy of Evidence: Levels of Study Design in Evidence-Based Practice

Level on the evidence pyramid	Study design
Level I	Systematic review or meta-analysis of randomized controlled trials (RCT)
Level II	A well-designed RCT
Level III	Controlled trial without randomization
Level IV	Single nonexperimental study
Level V	Systematic review of descriptive and qualitative studies
Level VI	Single descriptive or qualitative study
Level VII	Opinion of authorities and/or reports of expert committees