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Paper No. 13-11

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D Lamnisos, JE Griffin and MFJ Steel

Adaptive MC3 and Gibbs Algorithms for Bayesian Model Averaging in Linear Regression Models

Abstract: The MC3 (Madigan and York, 1995) and Gibbs (George and McCulloch, 1997) samplers are the most widely implemented algorithms for Bayesian Model Averaging (BMA) in linear regression models. These samplers draw a variable at random in each iteration using uniform selection probabilities and then propose to update that variable. This may be computationally inefficient if the number of variables is large and many variables are redundant. In this work, we introduce adaptive versions of these samplers that retain their simplicity in implementation and reduce the selection probabilities of the many redundant variables. The improvements in efficiency for the adaptive samplers are illustrated in real and simulated datasets.

Keywords: Adaptive MCMC; Gibbs sampler; Model uncertainty; Variable selection.