Type: Package Package: loo Title: Efficient Leave-One-Out Cross-Validation and WAIC for Bayesian Models Version: 2.10.0 Date: 2026-06-24 Authors@R: c( person("Aki", "Vehtari", email = "Aki.Vehtari@aalto.fi", role = "aut"), person("Jonah", "Gabry", email = "jgabry@gmail.com", role = c("cre", "aut")), person("Måns", "Magnusson", role = "aut"), person("Yuling", "Yao", role = "aut"), person("Paul-Christian", "Bürkner", role = "aut"), person("Topi", "Paananen", role = "aut"), person("Andrew", "Gelman", role = "aut"), person("Ben", "Goodrich", role = "ctb"), person("Juho", "Piironen", role = "ctb"), person("Bruno", "Nicenboim", role = "ctb"), person("Leevi", "Lindgren", role = "ctb"), person("Visruth", "Srimath Kandali", role = "ctb"), person("Florence", "Bockting", role = "ctb") ) Maintainer: Jonah Gabry Description: Efficient approximate leave-one-out cross-validation (LOO) for Bayesian models fit using Markov chain Monte Carlo, as described in Vehtari, Gelman, and Gabry (2017) . The approximation uses Pareto smoothed importance sampling (PSIS), a new procedure for regularizing importance weights. As a byproduct of the calculations, we also obtain approximate standard errors for estimated predictive errors and for the comparison of predictive errors between models. The package also provides methods for using stacking and other model weighting techniques to average Bayesian predictive distributions. License: GPL (>=3) URL: https://mc-stan.org/loo/, https://discourse.mc-stan.org BugReports: https://github.com/stan-dev/loo/issues Depends: R (>= 3.5) Imports: checkmate, matrixStats (>= 0.52), parallel, posterior (>= 1.7.0), stats Suggests: bayesplot (>= 1.7.0), brms (>= 2.10.0), ggplot2, graphics, knitr, rmarkdown, rstan, rstanarm (>= 2.19.0), rstantools, spdep, testthat (>= 3.0) VignetteBuilder: knitr Config/testthat/edition: 3 Config/testthat/parallel: true Config/testthat/start-first: loo_subsampling_cases, loo_subsampling Encoding: UTF-8 LazyData: TRUE Roxygen: list(markdown = TRUE) SystemRequirements: pandoc (>= 1.12.3), pandoc-citeproc Config/roxygen2/version: 8.0.0 Repository: https://r-multiverse.r-universe.dev Date/Publication: 2026-06-24 15:27:47 UTC RemoteUrl: https://github.com/stan-dev/loo RemoteRef: v2.10 RemoteSha: 1d6f5859ddf8792ce01d4a8f259c88d247b4ebb9 NeedsCompilation: no Packaged: 2026-07-01 09:09:01 UTC; root Author: Aki Vehtari [aut], Jonah Gabry [cre, aut], Måns Magnusson [aut], Yuling Yao [aut], Paul-Christian Bürkner [aut], Topi Paananen [aut], Andrew Gelman [aut], Ben Goodrich [ctb], Juho Piironen [ctb], Bruno Nicenboim [ctb], Leevi Lindgren [ctb], Visruth Srimath Kandali [ctb], Florence Bockting [ctb]