At kth interim look k = 1 k = 2 k = 3 total
Type I error
Empirical of S(t) 0.0028 0.0047 0.0422 0.0496
Nominal 0.0024 0.0046 0.0436 0.0506
Power        
Empirical of S(t) 0.171 0.2994 0.3886 0.8389
 Nominal 0.1204 0.2533 0.4257 0.7994
Probability of stopping under null
Empirical of S(t) 0.2574 0.3907 0.3519 1
Nominal 0.2626 0.3916 0.346 1
Probability of stopping under alternative
Empirical of S(t) 0.1756 0.315 0.5094 1
 Nominal 0.1315 0.28 0.5885 1
Table 3: Operating characteristics of the three-stage SCPRT design for test statistic S(t)based on 100,000 simulation runs under the Weibull distribution with uniform censoring distribution on [tf ,ta+ tf], and nominal type I error of 0.05 and power 80% for the example in Section 6.