Model selection for marginal regression analysis of longitudinal data is challenging owing to the presence of correlation and the difficulty of specifying the full likelihood, particularly for correlated categorical data. The paper introduces a novel Bayesian information criterion type model...

In many biomedical studies, we are interested in comparing treatment effects with an inherent ordering. We propose a "quadratic score test" (QST) based on a quadratic inference function for detecting an order in treatment effects for correlated data. The quadratic inference function is similar...

To construct an optimal estimating function by weighting a set of score functions, we must either know or estimate consistently the covariance matrix for the individual scores. In problems with high dimensional correlated data the estimated covariance matrix could be unreliable. The smallest...