Fig. 1From: Optimal futility stopping boundaries for binary endpointsRatio of \(n_1\) to n for \(p_a-p_0 = 0.15\), \(\alpha = 0.05\) and \(\beta = 0.2\). The dotted lines show the set boundaries for the proportion of \(n_1\) to n, here 1/3 and 2/3Back to article page