OCP_design <- function(design,t1,delta){ #--------------------------------------- # Recalculate second stage sample size #--------------------------------------- delta_obs <- t1*sqrt(2/design$n_1) n_recalc <- design$n_1*((qnorm(0.2)-qnorm(1-design$alpha_1)*sqrt(sqrt(design$n_1)^2+sqrt(design$n_1)^2)/sqrt(design$n_2))/t1 +sqrt(design$n_1)/sqrt(design$n_2))^2+design$n_1 n <- ifelse(t1>= qnorm(1-design$alpha_1)| t1< qnorm(1-design$alpha_0),design$n_1,ifelse(n_recalc