Compute the opposite of the loglikelihood function for CUSH models with covariates to explain the shelter effect.
effecush(paravec, esternocush, shelter, m)
Vector of the initial parameters estimates
Matrix binding together the vector of ordinal data and the matrix XX of explanatory variables whose first column is a column of ones needed to consider an intercept term
Category corresponding to the shelter choice
Number of ordinal categories
It is called as an argument for "optim" within CUSH function (when no covariate is included) as the function to minimize.