An Asymptotic Equation Linking WAIC and WBIC in Singular Models

Fuente: arXiv
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Main Authors: Hayashi, Naoki, Kutsuna, Takuro, Takamuku, Sawa
Format: Preprint
Published: 2025
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_version_ 1866908672518520832
author Hayashi, Naoki
Kutsuna, Takuro
Takamuku, Sawa
author_facet Hayashi, Naoki
Kutsuna, Takuro
Takamuku, Sawa
contents In statistical learning, models are classified as regular or singular depending on whether the mapping from parameters to probability distributions is injective. Most models with hierarchical structures or latent variables are singular, for which conventional criteria such as the Akaike Information Criterion and the Bayesian Information Criterion are inapplicable due to the breakdown of normal approximations for the likelihood and posterior. To address this, the Widely Applicable Information Criterion (WAIC) and the Widely Applicable Bayesian Information Criterion (WBIC) have been proposed. Since WAIC and WBIC are computed using posterior distributions at different temperature settings, separate posterior sampling is generally required. In this paper, we theoretically derive an asymptotic equation that links WAIC and WBIC, despite their dependence on different posteriors. This equation yields an asymptotically unbiased expression of WAIC in terms of the posterior distribution used for WBIC. The result clarifies the structural relationship between these criteria within the framework of singular learning theory, and deepens understanding of their asymptotic behavior. This theoretical contribution provides a foundation for future developments in the computational efficiency of model selection in singular models.
format Preprint
id arxiv_https___arxiv_org_abs_2505_13902
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An Asymptotic Equation Linking WAIC and WBIC in Singular Models
Hayashi, Naoki
Kutsuna, Takuro
Takamuku, Sawa
Machine Learning
Statistics Theory
62F15, 62R01
In statistical learning, models are classified as regular or singular depending on whether the mapping from parameters to probability distributions is injective. Most models with hierarchical structures or latent variables are singular, for which conventional criteria such as the Akaike Information Criterion and the Bayesian Information Criterion are inapplicable due to the breakdown of normal approximations for the likelihood and posterior. To address this, the Widely Applicable Information Criterion (WAIC) and the Widely Applicable Bayesian Information Criterion (WBIC) have been proposed. Since WAIC and WBIC are computed using posterior distributions at different temperature settings, separate posterior sampling is generally required. In this paper, we theoretically derive an asymptotic equation that links WAIC and WBIC, despite their dependence on different posteriors. This equation yields an asymptotically unbiased expression of WAIC in terms of the posterior distribution used for WBIC. The result clarifies the structural relationship between these criteria within the framework of singular learning theory, and deepens understanding of their asymptotic behavior. This theoretical contribution provides a foundation for future developments in the computational efficiency of model selection in singular models.
title An Asymptotic Equation Linking WAIC and WBIC in Singular Models
topic Machine Learning
Statistics Theory
62F15, 62R01
url https://arxiv.org/abs/2505.13902