The Rats data frame has 126 rows and 4 columns.
This data frame contains the following columns:
a numeric vector identifying the animal whose plasma level is measured.
a numeric vector giving the measured plasma level (microgram/mL).
a numeric vector giving the time since administration (hours).
a numeric vector indicating the dose administred (mg/kg).
Holder et al. (1999), Table 4 describes data on the plasma levels measured at 6 time points over 24 hours for 9
female rats. The same experiment was repeated with different oral dosages.