30 hip replacement patients were followed to examine differences by
gender and age in response to hip replacement therapy.  Each of several
variables was measured on four equally spaced occasions, once before
surgery and three times after.  The repeated measurements were on: 
haematocrit, TPP, vitamin E, vitamin A, urinary zinc, plasma zinc,
hydroxyprolene (mg), hydroxyprolene index, ascorbic acid, carotine,
calcium, and plasma phosphate. There are in addition six covariates 
measured at baseline: treatment group, gender, age, height, and weight. 
Researchers are interested in how each of the repeated measures differs 
by the baseline covariates. There were 13 men and 17 women.

Missing values are denoted by -9.

Data sources: 

Hand and Crowder (1996). Practical Longitudinal Data Analysis. 
London: Chapman and Hall. (Table B2) 

Crowder and Hand (1990). Analysis of Repeated Measures. London: 
Chapman and Hall. (Table 5.2)