R/loglikcubp0.R

In CUB: A Class of Mixture Models for Ordinal Data

#' @title Log-likelihood function of a CUB model with covariates for the uncertainty component
#' @description Compute the log-likelihood function of a CUB model fitting ordinal responses with covariates 
#' for explaining the uncertainty component.
#' @aliases loglikcubp0
#' @usage loglikcubp0(m, ordinal, Y, bbet, ccsi)
#' @param m Number of ordinal categories
#' @param ordinal Vector of ordinal responses
#' @param Y Matrix of selected covariates for explaining the uncertainty component
#' @param bbet Vector of parameters for the uncertainty component, with length equal to 
#' NCOL(Y)+1 to account for an intercept term (first entry of bbet)
#' @param ccsi Feeling parameter
#' @keywords internal


loglikcubp0 <-
function(m,ordinal,Y,bbet,ccsi){

  if (is.factor(ordinal)){
    ordinal<-unclass(ordinal)
  }
  Y<-as.matrix(Y)
  prob<-probbit(m,ccsi)
  probn<-prob[ordinal]
  eta<-logis(Y,bbet)
  return(sum(log(eta*(probn-1/m)+1/m)))
}