Table 2. Categorization of evidence (Eccles and Mason, 2001) (17).
Category | Methodological strength of evidence |
---|---|
I | Meta-analysis of randomized controlled trials (RCT) or at least one RCT |
II | A controlled study (non-randomized), other type of quasi-experimental study |
III | Nonexperimental descriptive studies, such as comparative studies, correlation studies, and case control studies |
IV | Evidence from expert committee reports or opinions and/or clinical experience of respected authorities |