One-sided α
β
1
0.1
0.2
0.3
≥0.4
0.025
α
2
0.3000
0.2250
0.2236
0.2236
0.05
α
2
0.5500
0.3500
0.3167
0.3162
Source: Chang [19].Statistics in Medicine, 26, 2772-2784.
Table 4:
Stopping boundaries for two-stage futility design.