Children with cancer were examined for antibody levels to a herpes virus. 45
children had either a solid lump tumor (n=18) or leukaemia (n=27). The 
measurements were taken during hospital visits for chemotherapy treatment, 
which lasted from 1 month to 3 years (median=12 months). Intervals between 
chemotherapy treatments were not the same for all children. The study was 
designed to examine whether the herpes virus antibody levels changed with 
chemotherapy treatment and whether any change was different for the two 
cancer types. This herpes virus antibody is known to decrease naturally with 
age.

The data show patient ID, age in years, age category (<= 1 year or >= 2 years), 
month of observation, month squared, month cubed, month to the fourth power, 
antibody level, and cancer type. (The powers of month can be used in a 
polynomial random coefficients model.)

These data are taken from Brown H and Prescott R (1999). Applied mixed models 
in medicine. Chichester, England: John Wiley & Sons, Inc.