Diagnostics for the LOO-IC ELPD approximation.

Pareto k is the primary diagnostic indicating whether the approximation is trustworthy and all Pareto k values should be below 0.7. The is the effective sample size and is the ratio of the effective sample size to the true sample size – if there are too few effective samples relative to actual samples, we can get an optimistic evaluation of the approximation quality, but in general this matters less if the ESS is sufficiently high. (XLSX)