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Fig. 1 | BMC Medical Research Methodology

Fig. 1

From: Choice of futility boundaries for group sequential designs with two endpoints

Fig. 1

Probability of stopping for futility (left figure) and overall power (right figure) for Approach 1 using the futility β γ-boundaries \(\alpha _{f}^{CE}=0.43\) and \(\alpha _{f}^{MC}=0.44\) for composite endpoint and main component, respectively. The vertical dotted line shows the sample size required to achieve a power of 0.9 for the reference design without futility stopping. Horizontal dotted lines indicate the thresholds for the rate of ’wrongly’ stopping for futility (left figure) and for the admissible power loss (right figure), respectively

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