Posterior propriety in Bayesian extreme value analyses using reference priors
arXiv:1505.04983 · doi:10.5705/ss.2014.034
Abstract
The Generalized Pareto (GP) and Generalized extreme value (GEV) distributions play an important role in extreme value analyses, as models for threshold excesses and block maxima respectively. For each of these distributions we consider Bayesian inference using "reference" prior distributions (in the general sense of priors constructed using formal rules) for the model parameters, specifically a Jeffreys prior, the maximal data information (MDI) prior and independent uniform priors on separate model parameters. We investigate the important issue of whether these improper priors lead to proper posterior distributions. We show that, in the GP and GEV cases, the MDI prior, unless modified, never yields a proper posterior and that in the GEV case this also applies to the Jeffreys prior. We also show that a sample size of three (four) is sufficient for independent uniform priors to yield a proper posterior distribution in the GP (GEV) case.
20 pages, 2 figures; typo corrected on page 5 (line -2, Euler's constant corrected to approx. 0.57722). The final publication is available at http://www3.stat.sinica.edu.tw/preprint/SS-14-034_preprint.pdf or http://dx.doi.org/10.5705/ss.2014.034