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Table 1 Empirical power 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
5 10% 1,418 0.8088 0.8054 0.8836
20% 798 0.8152 0.8082 0.8916
30% 608 0.8178 0.8014 0.8870
40% 532 0.8116 0.8036 0.8866
50% 512 0.8156 0.8098 0.8974
15 10% 178 0.8556 0.8204 0.8890
20% 100 0.8490 0.8128 0.8930
30% 78 0.8442 0.8316 0.9012
40% 68 0.8556 0.8322 0.9038
50% 64 0.8412 0.8256 0.9082
  1. The margin of error based on the 99% confidence interval is 0.015.