This function accepts a log-likelihood matrix produced by `id_post_pred` and extracts the IDs of the MCMC chains. It is necessary to use this function as the second argument to the `loo` function along with an exponentiated log-likelihood matrix. See the package vignette How to Evaluate Models for more details.
derive_chain(ll_matrix = NULL)
A log-likelihood matrix as produced by the id_post_pred
function