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Oxford Centre for Evidence-Based Medicine (OCEBM) levels of evidence
| Level of Evidence | Type of Study |
|---|---|
| I | Systematic reviews of RCT or individual RCT |
| II | Systematic reviews of cohort studies or individual cohort study |
| III | Systematic reviews of cohort studies, good quality case-control, or case-control study |
| IV | Case-series, poor-quality cohort, or case-control studies |
| V | Expert opinion |
