Data from an experiment with $i=1,...,59$ epilepsy patients. Each of the patients was assigned to a control group or a treatment group. The experiment recorded the number of seizures experienced by each patient over four two-week periods. The experiment also recorded a baseline count of the number of seizures the patients had experienced during the previous eight weeks.
data("epilepsy")A data frame with 236 observations on the following 6 variables.
countNumber of seizures experienced.
idPatient ID.
groupTreatment or control groups.
ageThe logarithm of the patient's age.
baseThe logarithm of baseline/4.
visitThe corresponding time period.
Thall, P. F. and Vail, S. C. (1990) Some covariance models for longitudinal count data with overdispersion In Biometrics 46, 657--671