R/drawUtility.R

In PatrickPfeifferDSc/bite: Bayesian Inference On Treatment Effects For Panel Data

#' Draw latent utilities
#'
#' [Internal] \code{draw_utility} draws latent utilities for the
#' probit model, which represents the selection of treatment. Latent
#' utilities (x*) range from -Inf to +Inf. For x* being positive, the
#' subject selects treatment, subject does not decide for treatment otherwise.
#'
#' @param x vector of subject features
#' @param mxst vector of means of utilities x*
#' @param sxst vector of standard deviations of utilities x*
#'
#' @importFrom truncnorm rtruncnorm
#'
#' @return xst x*, the latent utility for selection model

drawUtility <- function(x, mxst, sxst){
  n <- length(x)
  xst <- matrix(0, n, 1)
  for (j in 0:1){
    idx <- (x==j)
    if (j == 0){
      tau_low <- -Inf
      tau_high <- 0
    }else{
      tau_low <- 0
      tau_high <- Inf
    }
    if(length(sxst)==1){
        xst[idx,1] <- rtruncnorm(1, mean = mxst[idx], sd = sxst, a = tau_low, b = tau_high)
      }else{
        xst[idx,1] <- rtruncnorm(1, mean = mxst[idx], sd = sxst[idx], a = tau_low, b = tau_high)
      }
    }
  return(xst)
}