R/gsSurv-interim.R

In gsDesign: Group Sequential Design

# tEventsIA roxy [sinew] ----
#' @export
#' @rdname nSurv
#' @seealso
#'  \code{\link[stats]{uniroot}}
#' @importFrom stats uniroot
# tEventsIA function [sinew] ----
tEventsIA <- function(x, timing = .25, tol = .Machine$double.eps^0.25) {
  T <- x$T[length(x$T)]
  z <- uniroot(
    f = nEventsIA, interval = c(0.0001, T - .0001), x = x,
    target = timing, tol = tol, simple = TRUE
  )
  return(nEventsIA(tIA = z$root, x = x, simple = FALSE))
}

# nEventsIA roxy [sinew] ----
#' @export
#' @rdname nSurv
# nEventsIA function [sinew] ----
nEventsIA <- function(tIA = 5, x = NULL, target = 0, simple = TRUE) {
  Qe <- x$ratio / (1 + x$ratio)
  eDC <- eEvents(
    lambda = x$lambdaC, eta = x$etaC,
    gamma = x$gamma * (1 - Qe), R = x$R, S = x$S, T = tIA,
    Tfinal = x$T[length(x$T)], minfup = x$minfup
  )
  eDE <- eEvents(
    lambda = x$lambdaC * x$hr, eta = x$etaC,
    gamma = x$gamma * Qe, R = x$R, S = x$S, T = tIA,
    Tfinal = x$T[length(x$T)], minfup = x$minfup
  )
  if (simple) {
    if (class(x)[1] == "gsSize") {
      d <- x$d
    } else if (!is.matrix(x$eDC)) {
      d <- sum(x$eDC[length(x$eDC)] + x$eDE[length(x$eDE)])
    } else {
      d <- sum(x$eDC[nrow(x$eDC), ] + x$eDE[nrow(x$eDE), ])
    }
    return(sum(eDC$d + eDE$d) - target * d)
  } else {
    return(list(T = tIA, eDC = eDC$d, eDE = eDE$d, eNC = eDC$n, eNE = eDE$n))
  }
}