Artikel

Exact fit of simple finite mixture models

How to forecast next year's portfolio-wide credit default rate based on last year's default observations and the current score distribution? A classical approach to this problem consists of fitting a mixture of the conditional score distributions observed last year to the current score distribution. This is a special (simple) case of a finite mixture model where the mixture components are fixed and only the weights of the components are estimated. The optimum weights provide a forecast of next year's portfolio-wide default rate. We point out that the maximum-likelihood (ML) approach to fitting the mixture distribution not only gives an optimum but even an exact fit if we allow the mixture components to vary but keep their density ratio fixed. From this observation we can conclude that the standard default rate forecast based on last year's conditional default rates will always be located between last year's portfolio-wide default rate and the ML forecast for next year. As an application example, cost quantification is then discussed. We also discuss how the mixture model based estimation methods can be used to forecast total loss. This involves the reinterpretation of an individual classification problem as a collective quantification problem.

Language
Englisch

Bibliographic citation
Journal: Journal of Risk and Financial Management ; ISSN: 1911-8074 ; Volume: 7 ; Year: 2014 ; Issue: 4 ; Pages: 150-164 ; Basel: MDPI

Classification
Wirtschaft
Subject
quantification
prior class probability
probability of default

Event
Geistige Schöpfung
(who)
Tasche, Dirk
Event
Veröffentlichung
(who)
MDPI
(where)
Basel
(when)
2014

DOI
doi:10.3390/jrfm7040150
Handle
Last update
10.03.2025, 11:42 AM CET

Data provider

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Object type

  • Artikel

Associated

  • Tasche, Dirk
  • MDPI

Time of origin

  • 2014

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