L. Fahrmeir et al., An application of isotonic longitudinal marginal regression to monitoring the healing process, BIOMETRICS, 55(3), 1999, pp. 951-956
This paper discusses marginal regression for repeated ordinal measurements
that are isotonic over time. Such data are often observed in longitudinal s
tudies on healing processes in which, due to recovery, the status of patien
ts only improves or remains the same. We show how this prior information ca
n be used to construct appropriate and parsimoniously parametrized marginal
models. As a second aspect, we also incorporate nonparametric fitting of c
ovariate effects via a penalized quasi-likelihood or general estimating equ
ation approach. We illustrate our methods by an application to sports-relat
ed injuries.