R/est.power.R

In SurrogateRank: Rank-Based Test to Evaluate a Surrogate Marker

est.power <- function(n.total, rho = 0.80, u.y.alt, delta.alt, power.want.s = 0.7) {
  delta.se.est <- sqrt(2 * (1 - rho) / (3 * n.total))
  sd.null <- sqrt((n.total + 1) / (3 * n.total^2))
  z.alpha.2 <- qnorm(0.975)
  u.s.power <- 1 / 2 - (qnorm(1 - power.want.s) - z.alpha.2) * (sd.null)
  z.alpha <- qnorm(0.95)
  est.power <- pnorm((1 / delta.se.est) * (u.y.alt - u.s.power - delta.alt) - z.alpha)
  return(est.power)
}