The BodyWeight data frame has 176 rows and 4 columns.
This data frame contains the following columns:
a numeric vector giving the body weight of the rat (grams).
a numeric vector giving the time at which the measurement is made (days).
an ordered factor with levels 2 < 3 < 4
< 1 < 8 < 5 < 6 < 7 <
11 < 9 < 10 < 12 < 13 <
15 < 14 < 16 identifying the rat whose
weight is measured.
a factor with levels
1 to 3 indicating the diet that the rat receives.
Hand and Crowder (1996) describe data on the body weights of rats measured over 64 days. These data also appear in Table 2.4 of Crowder and Hand (1990). The body weights of the rats (in grams) are measured on day 1 and every seven days thereafter until day 64, with an extra measurement on day 44. The experiment started several weeks before ``day 1.'' There are three groups of rats, each on a different diet.