Semiparametric bivariate modelling with flexible extremal dependence

Leonelli, M. and Gamerman, D. (2020) Semiparametric bivariate modelling with flexible extremal dependence. Statistics and Computing, 30, pp. 221-236. (doi: 10.1007/s11222-019-09878-w)

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Inference over multivariate tails often requires a number of assumptions which may affect the assessment of the extreme dependence structure. Models are usually constructed in such a way that extreme components can either be asymptotically dependent or be independent of each other. Recently, there has been an increasing interest on modelling multivariate extremes more flexibly, by allowing models to bridge both asymptotic dependence regimes. Here we propose a novel semiparametric approach which allows for a variety of dependence patterns, be them extremal or not, by using in a model-based fashion the full dataset. We build on previous work for inference on marginal exceedances over a high, unknown threshold, by combining it with flexible, semiparametric copula specifications to investigate extreme dependence, thus separately modelling marginals and dependence structure. Because of the generality of our approach, bivariate problems are investigated here due to computational challenges, but multivariate extensions are readily available. Empirical results suggest that our approach can provide sound uncertainty statements about the possibility of asymptotic independence, and we propose a criterion to quantify the presence of either extreme regime which performs well in our applications when compared to others available. Estimation of functions of interest for extremes is performed via MCMC algorithms. Attention is also devoted to the prediction of new extreme observations. Our approach is evaluated through simulations, applied to real data and assessed against competing approaches. Evidence demonstrates that the bulk of the data do not bias and improve the inferential process for extremal dependence in our applications.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Leonelli, Dr Manuele
Authors: Leonelli, M., and Gamerman, D.
College/School:College of Science and Engineering > School of Mathematics and Statistics > Statistics
Journal Name:Statistics and Computing
ISSN (Online):1573-1375
Published Online:28 May 2019
Copyright Holders:Copyright © The Author(s) 2019
First Published:First published in Statistics and Computing 30:221-236
Publisher Policy:Reproduced under a Creative Commons license

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