“…The derivation of waic (Watanabe, 2018b) implies that the information required for evaluating the predictive ability of a model is contained in posterior distributions and can be extracted in the form of posterior covariance, at least in the lowest order of an asymptotic expansion with respect to the sample size. This principle is also seen in sensitivity estimation from mcmc outputs (e.g., Pérez et al, 2006;Giordano et al, 2018). This study aims to further pursue this idea and generalise waic for a wide range of predictive settings, including covariate-shift adaptation (e.g., Shimodaira, 2000;Sugiyama et al, 2007), counterfactual prediction (e.g., Platt et al, 2013;Baba et al, 2017), and quasi-Bayesian prediction (e.g., Konishi & Kitagawa, 1996;Yin, 2009).…”