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.

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.

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...

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...

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...

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...

A seller with some degree of market power in its product market can earn rents. In this context, there is a gain to granting credit to purchase of the product and thus to the establishment of a captive finance company. This paper examines the optimal behavior of such a durable good seller and...