Table 2 Types of Studies by Evidence Level
Level of Evidence | Types of Studies |
|---|---|
Level I | systematic review of level II studies, meta-analysis |
Level II | randomized control trial |
Level III-1 | pseudorandomized control trial |
Level III-2 | comparative studies including non-randomized experimental trials, cohort studies, case-control studies, interrupted time series with controls |
Level III-3 | comparative studies without controls including historical control studies, two or more single-arm studies, interrupted time series without a parallel control group, cross-sectional |
Level IV | case series, nonsystematic review, survey, qualitative interviews |