COW.DAT
Data file belonging to the GLM macro package of XploRe 3.0.
The data is from "Generalized Linear Models, 2nd Edition", McCullagh and 
Nelder (1989), Chapman and Hall, p. 201.
The observations are measurements in millimeters of a thickening of the skin
observable in a set number of hours after intradermal injection of the 
tuberculin. One hundred and twenty cows were divided into four classes (I-IV),
of 30 cows each. On each cow there were four sites of application, with each
cow receiving each of the four tuberculin treatments (A-D).

The first column is an index for the site of the neck (1-4).
The second column is an index for the cow class (see McCullagh and Nelder):
  1  =  I,  2 = II,  3 = III,  4 = IV
The third column is an index for the tuberculin treatments:
  1  =  A (standard double) ,  2  =  B (standard single),
  3  =  C (Weybridge single),  4  =  C (Weybridge half)
The fourth column gives the response in mm.
