Type of Copula       τ Global Power                             PFS                             OS   Analysis   1st Interim Final Analysis Power 1st Interim Final Analysis Power Independence 0 0.978 0.121 0.745 0.866 0.193 0.832 0.834 Normal 0.10 0.971 0.124 0.748 0.872 0.216 0.832 0.834   0.30 0.952 0.129 0.736 0.865 0.204 0.826 0.827   0.50 0.932 0.132 0.732 0.864 0.210 0.836 0.837   0.70 0.918 0.120 0.748 0.868 0.206 0.840 0.841 Frank 0.10 0.970 0.123 0.740 0.863 0.209 0.833 0.834   0.30 0.952 0.121 0.739 0.860 0.211 0.834 0.831   0.50 0.936 0.121 0.749 0.869 0.205 0.831 0.831   0.70 0.917 0.130 0.739 0.869 0.217 0.835 0.836 Gumbel 0.10 0.970 0.125 0.744 0.869 0.216 0.832 0.833   0.30 0.950 0.124 0.749 0.873 0.204 0.832 0.833   0.50 0.930 0.122 0.745 0.866 0.208 0.837 0.838   0.70 0.908 0.122 0.748 0.870 0.207 0.829 0.831

Table 6: Empirical global power, power for each endpoint and proportion of terminating the trial early using O'Brien-Fleming boundaries and assuming unequal allocation of the type I error rate of 0.03 for PFS and 0.02 for OS; results based on 10,000 simulations.