These data are from a longitudinal study of calcium absorption in 188 nuns.
Dietary balance and bone measurement tests were completed every five year.
The nuns ages ranged from 35 to 45 years at the study's onset (1960s). The
outcome of interest was adjusted absorption of calcium. Explanatory variables
were age, body surface area (BSA), body mass index (BMI), dietary calcium,
urine calcium, endogenous fecal calcium (EFC), total intestinal calcium (TIC),
dietary phosphorous, caffeine intake, and calcium balance.

The data set is calcium.dat with columns:

id 
age           age at study onset (years) 
calabs        calcium absorption
bsa           body surface area
bmi           body mass index (kg/m^2)
caldiet       dietary calcium
calurine      urine calcium
efc           endogenous fecal calcium
tic           total intestinal calcium
phosdiet      dietary phosphorous
caff          caffeine intake
calbal        calcium balance

The rows correspond to each visit for each nun and are given from first visit
to last visit; missing values are shown with a '.'. Nuns have from 1 to 4
visits total. The units in which the other variables were measured were not
given.

This data set is from Davis (2002) Statistical Methods for the Analysis of
Repeated Measurements. New York: Springer Verlag Inc. Problem 9.8.