Biometrika Advance Access published online on May 4, 2009
Biometrika, doi:10.1093/biomet/asp017
Article |
Objective Bayesian model selection in Gaussian graphical models
Booth School of Business, University of Chicago, Chicago, Illinois 60637, U.S.A. carlos.carvalho{at}chicagobooth.edu
Department of Statistical Science, Duke University, Durham, North Carolina 27708, U.S.A. james{at}stat.duke.edu
Received for publication 1 September 2007. Revision received 1 November 2008.
This paper presents a default model-selection procedure for Gaussian graphical models that involves two new developments. First, we develop a default version of the hyper-inverse Wishart prior for restricted covariance matrices, called the hyper-inverse Wishart g-prior, and show how it corresponds to the implied fractional prior for selecting a graph using fractional Bayes factors. Second, we apply a class of priors that automatically handles the problem of multiple hypothesis testing. We demonstrate our methods on a variety of simulated examples, concluding with a real example analyzing covariation in mutual-fund returns. These studies reveal that the combined use of a multiplicity-correction prior on graphs and fractional Bayes factors for computing marginal likelihoods yields better performance than existing Bayesian methods.
Key Words: Bayesian model selection Fractional Bayes factor Gaussian graphical model Hyper-inverse Wishart distribution Multiple hypothesis testing
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