Bayesian inference with dependent normalized completely random measures

TL;DR

This paper introduces a new class of dependent nonparametric priors based on normalized dependent completely random measures, providing analytical results and a sampling scheme for Bayesian inference, demonstrated through density estimation and clustering analysis.

Contribution

It develops a flexible framework for dependent priors using normalized completely random measures, with explicit sampling algorithms for practical Bayesian inference.

Findings

Derived distributional properties for the class of dependent CRMs.

Specialized the framework to bivariate Dirichlet and normalized sigma-stable processes.

Implemented a Markov Chain Monte Carlo algorithm for posterior inference.

Abstract

The proposal and study of dependent prior processes has been a major research focus in the recent Bayesian nonparametric literature. In this paper, we introduce a flexible class of dependent nonparametric priors, investigate their properties and derive a suitable sampling scheme which allows their concrete implementation. The proposed class is obtained by normalizing dependent completely random measures, where the dependence arises by virtue of a suitable construction of the Poisson random measures underlying the completely random measures. We first provide general distributional results for the whole class of dependent completely random measures and then we specialize them to two specific priors, which represent the natural candidates for concrete implementation due to their analytic tractability: the bivariate Dirichlet and normalized $\sigma$-stable processes. Our analytical results, and in particular the partially exchangeable partition probability function, form also the basis for the determination of a Markov Chain Monte Carlo algorithm for drawing posterior inferences, which reduces to the well-known Blackwell--MacQueen P\'{o}lya urn scheme in the univariate case. Such an algorithm can be used for density estimation and for analyzing the clustering structure of the data and is illustrated through a real two-sample dataset example.