Repeated ordinal measurements: a generalised estimating equation approach

Cumulative logit and related regression models for ordered categorical data may be expressed as generalised linear models for correlated binary responses. These may be fitted using the generalised estimated equation approach of Liang and Zeger (1986) and yields nearly identical results to maximum likelihood while offering further flexibility. The approach also generalises to deal with repeated ordinal measurements in the same subject, such as those commonly observed in medical cross-over experiments.