Template-Type: ReDIF-Paper 1.0 Author-Name: Bauwens, L. Author-Name-Last: Bauwens Author-Name-First: Luc Author-Person: pba4 Author-Name: Bos, C.S. Author-Name-Last: Bos Author-Name-First: Charles Author-Person: pbo94 Author-Name: van Dijk, H.K. Author-Name-Last: van Dijk Author-Name-First: Herman Author-Person: pva325 Title: Adaptive Polar Sampling with an Application to a Bayes Measure of Value-at-Risk Abstract: Adaptive Polar Sampling (APS) is proposed as a Markov chain Monte Carlo method for Bayesian analysis of models with ill-behaved posterior distributions. In order to sample efficiently from such a distribution, a location-scale transformation and a transformation to polar coordinates are used. After the transformation to polar coordinates, a Metropolis-Hastings algorithm is applied to sample directions and, conditionally on these, distances are generated by inverting the CDF. A sequential procedure is applied to update the location and scale. Tested on a set of canonical models that feature near non-identifiability, strong correlation, and bimodality, APS compares favourably with the standard Metropolis-Hastings sampler in terms of parsimony and robustness. APS is applied within a Bayesian analysis of a GARCH-mixture model which is used for the evaluation of the Value-at-Risk of the return of the Dow Jones stock index. Creation-Date: 1999-10-21 File-URL: https://repub.eur.nl/pub/7712/1999-0824.pdf File-Format: application/pdf Series: RePEc:ems:eureir Number: TI 99-082/4 Number: TI 99-082/4 Classification-JEL: C11, C15, C63 Keywords: GARCH, Markov Chain Monte Carlo, ill-behaved posterior, polar coordinates, simulation, value-at-risk Handle: RePEc:ems:eureir:7712