Korean Abstract: 신용등급은 기업의 미래 현금흐름과 위험을 예측하는 정보를 제공하고 기업의 내재가치를 반영하여 금융거래 시 비대칭정보인 차입기업의 위험유형을 선별하고 통제하는 기능을 수행한다. 본 연구는...

Parameter identifiability is very useful if one wishes to make inferences in a statistical model. There are two important nonidentifiabilities in finite mixture models : boundary nonidentifiability and label nonidentifiability. Although parameters are not identifiable in the strict sense, in...

We establish a sufficient condition for the occurrence of nonresponse boundary solutions in a two-way square contingency table with nonignorable nonresponse. The condition depends only on the observed counts and thus it does not require computing the maximum likelihood estimates.

The identification of an appropriate multivariate copula for capturing the dependence structure in multivariate data is not straightforward. The reason is because standard multivariate copulas (such as the multivariate Gaussian, Student-t, and exchangeable Archimedean copulas) lack flexibility...

Gaussian mixtures are very flexible in representing the underlying structure in the data. However, the likelihood inference for Gaussian mixtures with unrestricted covariance matrices is theoretically and practically challenging because the likelihood function is unbounded and often has multiple...

Finite mixtures of normal distributions are attractive in identifying the underlying group structure in the data. However, it is a challenging task to do statistical inference in normal mixture models using the method of maximum likelihood, due to the unbounded likelihood and the existence of...

We introduce a novel method of sensitivity analysis to aid in assessing the missing-at-random assumption in a two-way contingency table with one supplemental margin. The procedure involves a set of response odds and nonresponse odds computed from the observed counts.

Essay 1 provides an analytical model for risk segmentation in the perfectly competitive consumer loan market by incorporating the fact that a parental durable good seller with market power to some degree in its product market can earn rents. In this context, there is a gain to granting credit...