Comparison using WAIC
P ( Model 1 better than Model 2 ) = Φ ( elpd_diff / se_diff) prob_model_better <- function(elpd_diff, se_diff) { z <- elpd_diff / se_diff p <- pnorm(z) return(p) } elpd_diff <- 5 se_diff <- 3 prob_model_better ( elpd_diff , se_diff ) Result: [1] 0.952 So there is approximately 95% probability that model 1 predicts better than model 2 . It is not the probability that the model is better — only that its predictive accuracy is higher . You can use also the function Probability_Best_Model_WAIC() in HelpersMG packages that uses original loo results to compare the predictive accuracy of several models.