Table 2 Empirical type I error for all three methods when there was no misspecification of the distribution of the prognostic factor
θ | Planned distribution of the prognostic factor | Planned n t | Quota sampling | Modified quota sampling | Sample size re-estimation using conditional power |
|---|---|---|---|---|---|
0 | 10% | 1,418 | 0.0496 | 0.0534 | 0.0210 |
20% | 798 | 0.0484 | 0.0522 | 0.0260 | |
30% | 608 | 0.0494 | 0.0464 | 0.0286 | |
40% | 532 | 0.0510 | 0.0514 | 0.0302 | |
50% | 512 | 0.0532 | 0.0540 | 0.0248 | |
0 | 10% | 178 | 0.0494 | 0.0512 | 0.0248 |
20% | 100 | 0.0488 | 0.0516 | 0.0274 | |
30% | 78 | 0.0536 | 0.0524 | 0.0224 | |
40% | 68 | 0.0472 | 0.0496 | 0.0302 | |
50% | 64 | 0.0482 | 0.0482 | 0.0328 |