Table 2.
Reporting of parameters required for a priori sample size calculation for the 215 articles
| Parameter | Reporting frequency (%) |
|---|---|
| α risk | 191 (93) |
| 0.05 | 183 (96) |
| Two tailed test | 119 (65) |
| One tailed test | 7 (4) |
| Unspecified | 57 (31) |
| 0.025 for one tailed test | 2 (1) |
| Adapted for interim analyses | 6 (3) |
| Power | 200 (98) |
| 80% | 107 (54) |
| 85% | 9 (5) |
| 90% | 66 (33) |
| 95% | 4 (2) |
| Other values | 14 (7) |
| Assumptions for control group | 165 (81) |
| Justification of assumptions | 81 (49) |
| Results from previous trial | 54 (67) |
| Preliminary study | 15 (19) |
| Observational data | 6 (7) |
| Results of systematic review | 2 (3) |
| Others | 4 (5) |
| Assumptions for the treatment effect | 186 (91) |
| Justification of the assumptions | 50 (27) |
| Analogy to another trial or treatment | 41 (82) |
| Clinical relevance | 7 (14) |
| Observational data | 1 (2) |
| Results of a meta-analysis | 1 (2) |
| All parameters required for sample size calculation | 113 (53) |