An efficient method of posterior sampling for Poisson INGARCH models

📅 2026-03-08
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🤖 AI Summary
This study addresses the challenges of low posterior sampling efficiency and numerical instability in Poisson INGARCH models under strong temporal dependence. To overcome these issues, the authors introduce Pólya–Gamma data augmentation for the first time, leveraging a Poisson limit approximation of the negative binomial distribution to recast the posterior into a conditionally Gaussian form. This reformulation enables efficient Gibbs updates for autoregressive coefficients. The proposed method not only yields a stable approximate posterior suitable for strongly dependent settings but also serves as a high-quality proposal distribution for Metropolis–Hastings algorithms and adaptive importance sampling. Numerical experiments demonstrate that the approach substantially improves sampling efficiency, effective sample size, and chain mixing speed while maintaining accurate posterior inference.

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📝 Abstract
We develop an efficient posterior sampling scheme for the Poisson INGARCH models. The proposed method is based on the approximation of the posterior density that exploits the Poisson limit of the negative binomial distribution. It allows us to rewrite the model in a form amenable to P\'olya-Gamma data augmentation scheme, which yields simple conditionally Gaussian updates for the autoregressive coefficients. Sampling from the approximate posterior is straightforward via Gibbs-type iterations and remains numerically stable even under strong temporal dependence. Using this sampler as a proposal distribution will enhance the efficiency in Metropolis-Hastings algorithm and adaptive importance sampling. Numerical simulations indicate accurate posterior estimates, high effective sample sizes, and rapidly mixing chains.
Problem

Research questions and friction points this paper is trying to address.

posterior sampling
Poisson INGARCH
Markov chain Monte Carlo
temporal dependence
Bayesian inference
Innovation

Methods, ideas, or system contributions that make the work stand out.

Poisson INGARCH
Pólya-Gamma augmentation
posterior sampling
negative binomial approximation
Gibbs sampling