dataset = stackloss
begin description
Stack loss data from Rousseeuw and Leroy p. 76
Outliers are observations 1,3,4,21, and maybe 2.
Daniel and Wood suggest deleting 1-4 and 21 and that 6 groups remain
2; 5-8; 9; 10-14; 15-19; and 20
least squares coefs:
int           x1         x2         x3
-39.9190   0.715640    1.29529  -0.152131
 y=stackloss, x1=rate, x2=temp, x3=acid conc.
end description
begin variables
Col 0 = obs
Col 1 = y = stackloss
Col 2 = x1 = rate
Col 3 = x2 = temp
Col 4 = x3 = acid conc
end variables
begin data
 1   42   80   27   89
 2   37   80   27   88
 3   37   75   25   90
 4   28   62   24   87
 5   18   62   22   87
 6   18   62   23   87
 7   19   62   24   93
 8   20   62   24   93
 9   15   58   23   87
10   14   58   18   80
11   14   58   18   89
12   13   58   17   88
13   11   58   18   82
14   12   58   19   93
15    8   50   18   89
16    7   50   18   86
17    8   50   19   72
18    8   50   19   79
19    9   50   20   80
20   15   56   20   82
21   15   70   20   91