Functions and datasets for fitting models to Panel
data. These are described in, Gentleman, R.C., Lawless, J.F., Lindsey, J.C.
and Yan, P (1994).
Multi--state markov models for analyzing incomplete disease history
data with illustrations for HIV disease,
Statistics in Medicine, 13, 805--821.
Also those models described in Kalbfleisch, J. D. and Lawless J. F. (1985).
The analysis of panel data under a Markov assumption.
JASA 89, 863-871.
