Robust Bayesian analysis of heavy-tailed stochastic volatility models using scale mixtures of normal distributions

  • Authors:
  • C. A. Abanto-Valle;D. Bandyopadhyay;V. H. Lachos;I. Enriquez

  • Affiliations:
  • Department of Statistics, Federal University of Rio de Janeiro, Brazil;Department of Biostatistics, Bioinformatics and Epidemiology, Medical University of South Carolina, Charleston, SC, USA;Department of Statistics, Campinas State University, Brazil;Department of Statistics, São Paulo State University, Brazil

  • Venue:
  • Computational Statistics & Data Analysis
  • Year:
  • 2010

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Abstract

A Bayesian analysis of stochastic volatility (SV) models using the class of symmetric scale mixtures of normal (SMN) distributions is considered. In the face of non-normality, this provides an appealing robust alternative to the routine use of the normal distribution. Specific distributions examined include the normal, student-t, slash and the variance gamma distributions. Using a Bayesian paradigm, an efficient Markov chain Monte Carlo (MCMC) algorithm is introduced for parameter estimation. Moreover, the mixing parameters obtained as a by-product of the scale mixture representation can be used to identify outliers. The methods developed are applied to analyze daily stock returns data on S&P500 index. Bayesian model selection criteria as well as out-of-sample forecasting results reveal that the SV models based on heavy-tailed SMN distributions provide significant improvement in model fit as well as prediction to the S&P500 index data over the usual normal model.