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Table 2 Empirical type I error for all three methods when there was no misspecification of the distribution of the prognostic factor

From: Impact of misspecifying the distribution of a prognostic factor on power and sample size for testing treatment interactions in clinical trials

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
  1. The margin of error based on the 99% confidence interval is 0.008.