Table 6.

Error rates when treatment is added at interim, adjusting the upper boundary at the second stage. Based on 100,000 simulations

Design	$u_2^{\mathrm{adj}}$	${\stackrel{\wedge }{\alpha }}_{+}$	$1-{\stackrel{\wedge }{\beta }}_{+}$	$1-{\stackrel{\wedge }{\beta }}_{+}^{*}$
OBF	2.245	0.051	0.893	0.862
P	2.455	0.051	0.894	0.730
T	2.384	0.051	0.892	0.755