如何用SAS和模拟方法计算成组序贯实验的最小样本量？

Consider a group sequential design with K = 5 for early stopping for efficacy
only and the 4 α-spending functions

Use
simulation approaches to determine the minimum sample sizes needed to
detect the standardized treatment effect δ/σ = 0.25 with power 1−β = 0.90
at the significance level α = 0.05 (two-sided).