R/typeIerr.R

In AGSDest: Estimation in Adaptive Group Sequential Trials

#' \code{typeIerr} is a function that computes the type I error rate of a GSD.
#' @title type I error rate of a GSD
#' @param GSD object of the \code{class} \code{GSTobj} or list with the following elements: K = number of stages, a = vector with futility boundaries (not supported yet), b = rejection boundaries, t = vector with information fractions; see example blow.
#' @return \code{typeIerr} returns the type I error rate of a GSD.  
#' @references
#' O'Brien, PC, Fleming, TR (1979) ''A multiple testing procedure for clinical trials'',
#' \emph{Biometrics}, 35 , 549-556
#'
#' Schoenfeld, D (2001) ''A simple Algorithm for Designing Group Sequential Clinical Trials'',
#' \emph{Biometrics}, 27, 972-974 
#' @author Niklas Hack \email{niklas.hack@@meduniwien.ac.at} and Werner Brannath \email{werner.brannath@@meduniwien.ac.at}
#' @seealso \code{\link{GSTobj}}
#' @examples
#' ##The following calculates the type I error rate of a GSD. 
#' 
#' GSD <- list(K=4,a=rep(-8,4),b=c(4.333,2.963,2.359,2.014),
#' t=c(0.25,0.5,0.75,1),Imax=0.22)
#'
#' typeIerr(GSD)
#'
#' @keywords methods
#' @export
typeIerr <- function(GSD) {
    if(is.null(GSD$Imax)) GSD$Imax <- 1 
    sword(h=0, k=length(GSD$t), GSD=GSD)
}