Derive the variance covariance matrix of the design

The function is a wrapper around derive_vcov_mnl and derive_vcov_rpl and calculates the variance-covariance matrix of the specified model and design given the priors.

derive_vcov(design_env, model)

Arguments

design_env

An environment containing all the elements necessary to derive the variance-covariance matrix

model

A string indicating the model for which you wish to derive the variance covariance matrix. Can be either "mnl" or "rpl"

Value

The variance covariance matrix. If the Fisher information matrix is singular, then return NULL