Generalized estimating equations (Liang, K. Y. and Zeger, S., 1986, Biometrika 73, 13-22) allow longitudinal or clustered data to be modeled with minimal assumptions about their dependence structures.

Researchers and practitioners should only use the mixture methodology when substantive theory supports the structural equation model, a priori segmentation is infeasible, and theory suggests that the ...

Instead, we develop a multivariate model for ordinal trait analysis and implement an EM algorithm for parameter estimation.