Testing order restrictions in contingency tables

Abstract: Several interesting models for contingency tables are defined by a system of equality and inequality constraints on a suitable set of marginal log-linear parameters. After reviewing the most common difficulties which are intrinsic to order restricted testing problems, we propose two new families of testing procedures, based on similar attempts appeared in the econometric literature, in order to increase the probability of detecting several relevant violations of the supposed order relations. One set of procedures is based on the decomposition of the log-likelihood ratio when testing the given set of inequalities and the nested model derived by forcing inequalities into strict equalities. The other set uses the asymptotic joint normal distribution of the estimates of the marginal log-linear parameters to be constrained.