A sum characterization of hidden regular variation with likelihood inference via expectation-maximization

作者：Weller Grant B^*; Cooley Daniel

来源：Biometrika, 2014, 101(1): 17-36.

DOI：10.1093/biomet/ast046

• Air pollution
• Asymptotic independence
• EM algorithm
• Multivariate extreme value theory
• Tail dependence
• Threshold exceedance modelling

A fundamental deficiency of classical multivariate extreme value theory is the inability to distinguish between asymptotic independence and exact independence. In this work, we examine multivariate threshold modelling in the framework of regular variation on cones. Tail dependence is described by a limiting measure, which in some cases is degenerate on joint tail regions despite strong subasymptotic dependence in such regions. Hidden regular variation, a higher-order tail decay on these regions, offers a refinement of the classical theory. We develop a representation of random vectors possessing hidden regular variation as the sum of independent regular varying components. The representation is shown to be asymptotically valid via a multivariate tail equivalence result. We develop a likelihood-based estimation procedure from this representation via a Monte Carlo expectation-maximization algorithm which has been modified for tail estimation. The method is demonstrated on simulated data and applied to air pollution measurements.

• 出版日期2014-3