| Ranking of evidence by study type | |
| T1 | Randomised controlled trial (RCT) |
| T2 | Controlled trial (CT) |
| T3 | Controlled before-and-after intervention study (CBA) |
| O1 | Cohort study / longitudinal study |
| O2 | Case-control study |
| O3 | Cross-sectional |
| O4 | Study using qualitative methods only |
| O5 | Case series |
| O6 | Case study |
| X | Formal consensus or other professional (expert) opinion (automatic exclusion) |
Ranking of evidence by study type