Bayesian Inference and Prediction for Mean and Variance Shifts in Autoregressive Time Series

Abstract

This article is concerned with statistical inference and prediction of mean and variance changes in an autoregressive time series. We first extend the analysis of random mean-shift models to random variance-shift models. We then consider a method for predicting when a shift is about to occur. This involves appending to the autoregressive model a probit model for the probability that a shift occurs given a chosen set of explanatory variables. The basic computational tool we use in the proposed analysis is the Gibbs sampler. For illustration, we apply the analysis to several examples.

Key Words:

• Gibbs sampler
• Outlier
• Probit model
• Random level-shift model
• Random variance-shift model
• Variance change