Fig. 1From: Optimality criteria for futility stopping boundaries for group sequential designs with a continuous endpointThe “optimal” futility boundary α0,opt as a function of the admissible parameters Powloss and πwrong for N=140 (blue dots) and n=188 (red squares). The black symbols highlight the “optimal” futility boundaries for Powloss=0.05 and πwrong=0.05Back to article page