R/sigma2_hat.R

In EL2Surv: Empirical Likelihood (EL) for Comparing Two Survival Functions

sigma2_hat <- function(t, fit, fit1, fit2) {
  n   <- fit$n
  out <- 1:length(t)*0
  for (i in 1:length(t)) {
    d1     <- fit1$n.event[fit1$time <= t[i] & fit1$n.event != 0]
    r1     <- fit1$n.risk [fit1$time <= t[i] & fit1$n.event != 0]
    d2     <- fit2$n.event[fit2$time <= t[i] & fit2$n.event != 0]
    r2     <- fit2$n.risk [fit2$time <= t[i] & fit2$n.event != 0]
    out[i] <- n*(sum(division00(d1, r1*(r1 - d1))) + sum(division00(d2, r2*(r2 - d2))))
  }
  return (out)
}