🤖 AI Summary
In high-dimensional regression, conventional shrinkage priors often ignore dependence structures among regression coefficients, leading to substantial estimation bias under strongly correlated predictors. This paper proposes a dependency-aware global-local shrinkage prior that explicitly incorporates predictor correlations into a continuous shrinkage framework—achieved by generalizing the Zellner g-prior to induce a structured coefficient covariance matrix. Theoretically, we characterize how dependency modeling affects prior and posterior distributions, and derive conditions under which it yields differential gains in coefficient recovery versus prediction. Monte Carlo simulations and empirical studies demonstrate that the method substantially improves coefficient estimation accuracy in strongly correlated settings, yet delivers only marginal improvements in predictive performance. Our findings underscore that dependency modeling must be carefully tailored to the inferential objective—e.g., interpretability versus prediction—thereby establishing a new paradigm for Bayesian sparse modeling in high dimensions.
📝 Abstract
In high dimensional regression, global local shrinkage priors have gained significant traction for their ability to yield sparse estimates, improve parameter recovery, and support accurate predictive modeling. While recent work has explored increasingly flexible shrinkage prior structures, the role of explicitly modeling dependencies among coefficients remains largely unexplored. In this paper, we investigate whether incorporating such structures into traditional shrinkage priors improves their performance. We introduce dependency-aware shrinkage priors, an extension of continuous shrinkage priors that integrates correlation structures inspired by Zellner's g prior approach. We provide theoretical insights into how dependence alters the prior and posterior structure, and evaluate the method empirically through simulations and real data. We find that modeling dependence can improve parameter recovery when predictors are strongly correlated, but offers only modest gains in predictive accuracy. These findings suggest that prior dependence should be used selectively and guided by the specific inferential goals of the analysis.