The effect of the number of states on the validity of credit ratings

3rd International Conference on Mathematical Modeling in Physical Sciences

物理学;数学

Lencastre, P.^1,2 ; Raischel, F.^3 ; Lind, P.G.^4

ISCTE-IUL, Av. Forças Armadas, Lisboa

1649-026, Portugal^1

Mathematical Department, FCUL, University of Lisbon, Lisbon

1749-016, Portugal^2

Instituto Dom Luiz, University of Lisbon, Lisbon

1749-016, Portugal^3

ForWind and Institute of Physics, University of Oldenburg, Ammerländer Heerstrasse 136, Oldenburg

DE-26111, Germany^4

关键词: Credit ratings;    Dynamical properties;    Matrix estimation;    Number of state;    Open Access;    States change;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/574/1/012151/pdf
DOI  :  10.1088/1742-6596/574/1/012151

来源: IOP

【 摘 要 】

We explicitly test if the reliability of credit ratings depends on the total number of admissible states. We analyse open access credit rating data and show that the effect of the number of states in the dynamical properties of ratings change with time, thus giving supportive evidence that the ideal number of admissible states changes with time. We use matrix estimation methods that explicitly assume the hypothesis needed for the process to be a valid rating process. By comparing with the likelihood maximization method of matrix estimation, we quantify the "likelihood-loss" of assuming that the process is a well grounded rating process.