R/bread.heckmanGE.R

In heckmanGE: Estimation and Inference for Heckman Selection Models with Cluster-Robust Variance

#' bread.heckmanGE
#'
#' Bread Function for the `fitheckmanGE` Model
#'
#' This function calculates the "bread" component of the sandwich estimator for
#' the `fitheckmanGE` model. The bread matrix is typically defined as the product
#' of the number of observations and the variance-covariance matrix of the
#' estimated parameters.
#'
#' @param object An object of class `fitheckmanGE`, which is the result of fitting
#' a Heckman selection model using the `fitheckmanGE` function.
#' @param \dots Additional arguments (currently unused).
#'
#' @return A matrix representing the bread component of the sandwich estimator. The
#' matrix is calculated as the product of the number of observations and the
#' variance-covariance matrix of the estimated parameters.
#'
#' @details
#' The bread matrix is an essential component of the sandwich estimator used to
#' obtain robust standard errors. It reflects the variability in the estimated
#' parameters due to the model's fit. The function uses the number of observations
#' and the variance-covariance matrix from the `fitheckmanGE` model object to
#' compute this matrix.
#'
#' @export
bread.heckmanGE <- function(object, ...) {
        object$nObs * object$vcov  #deveriamos usar nObs ou a soma dos pesos?
}