To Vary or Not To Vary: A Flexible Empirical Bayes Factor for Testing Variance Components

Fuente: arXiv
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Hauptverfasser: Vieira, Fabio, Zhao, Hongwei, Mulder, Joris
Format: Preprint
Veröffentlicht: 2025
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author Vieira, Fabio
Zhao, Hongwei
Mulder, Joris
author_facet Vieira, Fabio
Zhao, Hongwei
Mulder, Joris
contents Random effects are the gold standard for capturing structural heterogeneity in data, such as spatial dependencies, individual differences, or temporal dependencies. However, testing for their presence is challenging, as it involves a variance component constrained to be non-negative -- a boundary problem. This paper proposes a flexible empirical Bayes factor (EBF) for testing random effects. Rather than testing whether a variance component is zero, the EBF tests the equivalent hypothesis that all random effects are zero. Crucially, it avoids manual prior specification based on external knowledge, as the distribution of random effects is part of the model's lower level and estimated from the data -- yielding an "empirical" Bayes factor. The EBF uses a Savage-Dickey density ratio, allowing all random effects to be tested using only the full model fit. This eliminates the need to fit multiple models with different combinations of random effects. Simulations on synthetic data evaluate the criterion's general behavior. To demonstrate its flexibility, the EBF is applied to generalized linear crossed mixed models, spatial random effects models, dynamic structural equation models, random intercept cross-lagged panel models, and nonlinear mixed effects models.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01403
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle To Vary or Not To Vary: A Flexible Empirical Bayes Factor for Testing Variance Components
Vieira, Fabio
Zhao, Hongwei
Mulder, Joris
Methodology
Random effects are the gold standard for capturing structural heterogeneity in data, such as spatial dependencies, individual differences, or temporal dependencies. However, testing for their presence is challenging, as it involves a variance component constrained to be non-negative -- a boundary problem. This paper proposes a flexible empirical Bayes factor (EBF) for testing random effects. Rather than testing whether a variance component is zero, the EBF tests the equivalent hypothesis that all random effects are zero. Crucially, it avoids manual prior specification based on external knowledge, as the distribution of random effects is part of the model's lower level and estimated from the data -- yielding an "empirical" Bayes factor. The EBF uses a Savage-Dickey density ratio, allowing all random effects to be tested using only the full model fit. This eliminates the need to fit multiple models with different combinations of random effects. Simulations on synthetic data evaluate the criterion's general behavior. To demonstrate its flexibility, the EBF is applied to generalized linear crossed mixed models, spatial random effects models, dynamic structural equation models, random intercept cross-lagged panel models, and nonlinear mixed effects models.
title To Vary or Not To Vary: A Flexible Empirical Bayes Factor for Testing Variance Components
topic Methodology
url https://arxiv.org/abs/2508.01403