Type 1 error Power
Design κ Test At kth interim look k = 1 k = 2 total k = 1 k = 2 total

δ=1.5
0.5 Z(t) Empirical 0.0067 0.0457 0.0524 0.3659 0.4293 0.7952
    S(t) Empirical 0.0082 0.0435 0.0517 0.4104 0.3887 0.7992
    L(t) Empirical 0.0066 0.046 0.0526 0.3545 0.4402 0.7947
      Nominal 0.0068 0.0435 0.0503 0.3686 0.4311 0.7997
  1 Z(t) Empirical 0.0052 0.0484 0.0535 0.2874 0.5062 0.7936
    S(t) Empirical 0.0066 0.0454 0.0521 0.3397 0.4594 0.799
    L(t) Empirical 0.0058 0.0483 0.0541 0.2674 0.5245 0.7918
      Nominal 0.0055 0.045 0.0505 0.2912 0.5083 0.7995
  2.0 Z(t) Empirical 0.0037 0.0503 0.054 0.185 0.6096 0.7946
    S(t) Empirical 0.0054 0.0448 0.0502 0.2541 0.547 0.801
    L(t) Empirical 0.0043 0.0498 0.0541 0.1655 0.6257 0.7912
      Nominal 0.0045 0.0463 0.0508 0.1997 0.5994 0.7991

δ =1.7
0.5 Z(t) Empirical 0.0037 0.0457 0.0494 0.2611 0.556 0.8171
    S(t) Empirical 0.0059 0.0455 0.0514 0.3054 0.4989 0.8043
    L(t) Empirical 0.0041 0.0457 0.0497 0.2708 0.5467 0.8176
      Nominal 0.0054 0.0451 0.0505 0.2851 5144 0.7995
  1 Z(t) Empirical 0.0023 0.047 0.0493 0.1612 0.6522 0.8134
    S(t) Empirical 0.0052 0.0479 0.0531 0.2259 0.5806 0.8065
    L(t) Empirical 0.0029 0.0466 0.0495 0.1753 0.5245 0.7918
      Nominal 0.0045 0.0462 0.0508 0.2049 0.5943 0.7992
  2 Z(t) Empirical 0.0014 0.0486 0.0499 0.0607 0.7496 0.8104
    S(t) Empirical 0.0046 0.0477 0.0523 0.1366 0.704 0.8031
    L(t) Empirical 0.0024 0.0486 0.051 0.0858 0.7227 0.8085
      Nominal 0.0043 0.0471 0.0514 0.1259 0.6726 0.7985

δ= 1.9
0.5 Z(t) Empirical 0.0022 0.0452 0.0474 0.2041 0.629 0.833
    S(t) Empirical 0.0051 0.0465 0.0516 0.2732 0.5402 0.8135
    L(t) Empirical 0.003 0.0449 0.0479 0.2326 0.6015 0.8341
      Nominal 0.005 0.0455 0.0505 0.2574 0.542 0.7994
  1 Z(t) Empirical 0.0011 0.0453 0.0464 0.0947 0.733 0.8276
    S(t) Empirical 0.0046 0.0472 0.0518 0.1883 0.6239 0.8122
    L(t) Empirical 0.003 0.0449 0.0479 0.2326 0.6015 0.8341
      Nominal 0.004 0.0465 0.0509 0.1803 0.6187 0.799
  2 Z(t) Empirical 0.0002 0.047 0.0472 0.0067 0.8168 0.8235
    S(t) Empirical 0.005 0.0484 0.0533 0.1005 0.704 0.8045
    L(t) Empirical 0.0017 0.0468 0.0485 0.0513 0.771 0.8224
      Nominal 0.0044 0.0473 0.0516 0.1084 0.6899 0.7983
Table 2: Simulated empirical type I error and power of the two-stage SCPRT designs based on 100,000 simulation runs for sequential Z(t), log-rank L(t) and S(t) tests with a nominal type I error of 0.05 and power 80% (one-sided test).