Evidence | |
---|---|
Ia | Evidence from meta-analysis of randomised controlled trials |
Ib | Evidence from at least one randomised controlled trial |
IIa | Evidence from at least one controlled study without randomisation |
IIb | Evidence from at least one other type of quasi-experimental study |
III | Evidence from non-experimental descriptive studies, such as comparative studies, correlation studies, and case-control studies |
IV | Evidence from expert committee reports, or opinions or clinical experience of respected authorities, or both |