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Hierarchically Coupled Gaussian Bayesian Networks
Proceedings of the 13th International Conference on Probabilistic Graphical Models, PMLR 343:523-544, 2026.
Abstract
Gaussian Bayesian networks are probabilistic graphical models for learning network structures from continuous data. Standard approaches typically assume that all observations arise from a homogeneous population. In many applications, however, the data originate from multiple related but heterogeneous groups that share a common network structure while having group-specific network parameters. Pooling all observations and inferring a single set of parameters ignores between-group heterogeneity and may lead to biased inference. Conversely, estimating group-specific parameters independently substantially increases model complexity and inferential uncertainty. We introduce a hierarchical prior that enables information sharing across groups. The proposed prior preserves group-specific parameters while introducing shrinkage by coupling the group-specific mean vectors and covariance structures through shared global hyperparameters. The corresponding coupling strengths are inferred from the data, allowing the degree of information sharing to adapt automatically to the observed heterogeneity across groups. We develop a Markov chain Monte Carlo (MCMC) algorithm for posterior inference and demonstrate empirically that the proposed approach improves both network structure learning and predictive performance.