R/bootstrapCI.R

In chariff/Cytometree: Automated Cytometry Gating and Annotation

#'Bootstrapped Confidence Interval.
#'
#'@param stat A numeric vector of statistics for which to compute a 
#'confidence interval.
#'
#'@param alpha A real number comprised in ]0, 1[ : 
#'1 - desired confidence level.
#'
#'@param n An integer giving the number of bootstrap samples.
#'
#'@author Chariff Alkhassim
#'
#'@export 
bootstrapCI <- function(stat, n, alpha){
  x_bar <- mean(stat)
  m <- length(stat)
  x_bar_star <- rowMeans(matrix(sample(stat, m*n, replace=TRUE), ncol=m))
  delta_star <- sort(x_bar_star) - x_bar
  percentile_sup <- floor(n*(1-alpha))
  percentile_inf <- n - percentile_sup
  inf_val <- x_bar - delta_star[percentile_sup]
  sup_val <- x_bar - delta_star[percentile_inf]
  return(list("inf"= inf_val,"sup"= sup_val))
}