Type of Copula      τ Global Power                            PFS                             OS       1st Interim Final Analysis Power 1st Interim Final Analysis Power Independence 0 0.979 0.206 0.647 0.853 0.221 0.855 0.856 Normal 0.10 0.969 0.205 0.645 0.851 0.211 0.849 0.849   0.30 0.955 0.202 0.646 0.848 0.217 0.852 0.853   0.50 0.934 0.209 0.639 0.849 0.216 0.860 0.860   0.70 0.912 0.203 0.644 0.847 0.209 0.855 0.856 Frank 0.10 0.974 0.203 0.646 0.850 0.206 0.856 0.857   0.30 0.957 0.207 0.645 0.852 0.215 0.856 0.857   0.50 0.938 0.203 0.647 0.850 0.218 0.852 0.853   0.70 0.912 0.204 0.640 0.844 0.215 0.854 0.855 Gumbel 0.10 0.969 0.209 0.638 0.846 0.221 0.853 0.854   0.30 0.947 0.208 0.638 0.846 0.217 0.854 0.854   0.50 0.929 0.208 0.639 0.847 0.210 0.857 0.857   0.70 0.909 0.212 0.638 0.850 0.216 0.854 0.855

Table 2: Empirical global power, power for each endpoint and proportion of terminating the trial early assuming equal allocation of type I error rate of 0.025 for each endpoint and using O'Brien-Fleming boundaries; results based on 10,000 simulations.