Fig. 3
Proportion of significant tests with distribution of conclusions for each design and specific case (pC = 0.50). Abbreviations: pC indicates control survival rate; ∆: simulated survival rate difference; F1: fixed single-arm design; S1: group-sequential single-arm design; F2: fixed two-arm design; S2: group-sequential two-arm design; “Standard”: specific case with a fixed control survival rate; “Changing with time”: specific case with an increase of the control survival rate over time; “Stopping of recruitment”: specific case with a fixed control survival rate and an early stop of the trial due to an outbreak end. For group-sequential trials, the total of trials demonstrating an efficacy of the experimental treatment was defined by the sum of trials with a significant test and trials with an adjusted p-value inferior to 0.025. The p-value was adjusted for underrunning by the method proposed by Whitehead [18]