Robust mixture modeling using the skew t distribution

  • Authors:
  • Tsung I. Lin;Jack C. Lee;Wan J. Hsieh

  • Affiliations:
  • Department of Applied-Mathematics, National Chung Hsing University, Taichung, Taiwan;Graduate Institute of Finance, National Chiao Tung University, Hsinchu, Taiwan;Institute of Statistics, National Chiao Tung University, Hsinchu, Taiwan

  • Venue:
  • Statistics and Computing
  • Year:
  • 2007

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Abstract

A finite mixture model using the Student's t distribution has been recognized as a robust extension of normal mixtures. Recently, a mixture of skew normal distributions has been found to be effective in the treatment of heterogeneous data involving asymmetric behaviors across subclasses. In this article, we propose a robust mixture framework based on the skew t distribution to efficiently deal with heavy-tailedness, extra skewness and multimodality in a wide range of settings. Statistical mixture modeling based on normal, Student's t and skew normal distributions can be viewed as special cases of the skew t mixture model. We present analytically simple EM-type algorithms for iteratively computing maximum likelihood estimates. The proposed methodology is illustrated by analyzing a real data example.