Table 5 Empirical power and the percentage of trials stopping for futility and efficacy for sample size re-estimation using conditional power
θ | Planned distribution of the prognostic factor | Planned n t | Empirical power | Percent stopping for futility | Percent stopping for efficacy |
|---|---|---|---|---|---|
Misspecification of the prognostic factor: -5% | |||||
5 | 10% | 1,418 | 0.7324 | 16.58% | 5.76% |
20% | 798 | 0.8410 | 10.34% | 11.76% | |
30% | 608 | 0.8616 | 9.02% | 13.72% | |
40% | 532 | 0.8754 | 8.24% | 15.42% | |
50% | 512 | 0.8868 | 7.64% | 16.22% | |
15 | 10% | 178 | 0.7246 | 17.14% | 7.90% |
20% | 100 | 0.8232 | 12.26% | 11.82% | |
30% | 78 | 0.8736 | 8.94% | 14.76% | |
40% | 68 | 0.8936 | 7.72% | 15.80% | |
50% | 64 | 0.9010 | 7.10% | 16.38% | |
Misspecification of the prognostic factor: -15% | |||||
5 | 10% | 1,418 | -- | -- | -- |
20% | 798 | 0.5614 | 26.06% | 3.5% | |
30% | 608 | 0.7536 | 15.46% | 7.3% | |
40% | 532 | 0.8304 | 10.72% | 10.80% | |
50% | 512 | 0.8750 | 8.34% | 14.32% | |
15 | 10% | 178 | -- | -- | -- |
20% | 100 | 0.6026 | 22.68% | 4.96% | |
30% | 78 | 0.7634 | 15.76% | 8.50% | |
40% | 68 | 0.8412 | 10.78% | 11.86% | |
50% | 64 | 0.8734 | 9.32% | 14.76% | |
Misspecification of the prognostic factor: +5% | |||||
5 | 10% | 1,418 | 0.9528 | 3.10% | 27.44% |
20% | 798 | 0.9194 | 5.58% | 20.94% | |
30% | 608 | 0.9064 | 6.26% | 18.36% | |
40% | 532 | 0.8898 | 7.18% | 17.16% | |
50% | 512 | 0.8868 | 7.52% | 16.02% | |
15 | 10% | 178 | 0.9476 | 3.94% | 29.36% |
20% | 100 | 0.9194 | 5.70% | 21.78% | |
30% | 78 | 0.9204 | 5.94% | 20.38% | |
40% | 68 | 0.9146 | 6.36% | 18.28% | |
50% | 64 | 0.9056 | 6.96% | 15.88% | |
Misspecification of the prognostic factor: +15% | |||||
5 | 10% | 1,418 | 0.9868 | 0.94% | 45.24% |
20% | 798 | 0.9494 | 3.38% | 27.26% | |
30% | 608 | 0.9186 | 5.34% | 20.84% | |
40% | 532 | 0.8990 | 6.98% | 17.12% | |
50% | 512 | 0.8822 | 8.00% | 14.30% | |
15 | 10% | 178 | 0.9902 | 0.78% | 49.94% |
20% | 100 | 0.9584 | 3.18% | 29.86% | |
30% | 78 | 0.9412 | 4.32% | 22.32% | |
40% | 68 | 0.9108 | 6.56% | 17.12% | |
50% | 64 | 0.8816 | 8.76% | 13.84% | |