We propose a Bayesian nonparametric model to estimate rating migration matrices and default probabilities using the reinforced urn processes (RUP) introduced in Muliere et al. (2000). The estimated default probability becomes our prior information in a parametric model for the prediction of the number of bankruptcies, with the only assumption of exchangeability within rating classes. The Polya urn construction of the transition matrix justifies a Beta distributed de Finetti measure. Dependence among the processes is introduced through the dependence among the default probabilities, with the Bivariate Beta Distribution proposed in Olkin and Liu (2003) and its multivariate generalization. (C) 2014 Elsevier B.V. All rights reserved.

Reinforced urn processes for credit risk models

MIRA, ANTONIETTA;
2015-01-01

Abstract

We propose a Bayesian nonparametric model to estimate rating migration matrices and default probabilities using the reinforced urn processes (RUP) introduced in Muliere et al. (2000). The estimated default probability becomes our prior information in a parametric model for the prediction of the number of bankruptcies, with the only assumption of exchangeability within rating classes. The Polya urn construction of the transition matrix justifies a Beta distributed de Finetti measure. Dependence among the processes is introduced through the dependence among the default probabilities, with the Bivariate Beta Distribution proposed in Olkin and Liu (2003) and its multivariate generalization. (C) 2014 Elsevier B.V. All rights reserved.
2015
Default rate estimation; Multivariate Beta distribution; Polya urn; Rating migration matrix estimation; Reinforced urn processes;
Peluso, Stefano; Mira, Antonietta; Muliere, Pietro
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2051231
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