When a continuous variable nests or crosses with a classification variable, the design columns are constructed by multiplying the continuous values into the design columns for the classification effect (Table 19.7).
Table 19.7: Example of ContinuousNestingClass Effects
Data 
I 







A1 
A2 
X(A1) 
X(A2) 

21 
1 
1 
1 
0 
21 
0 

24 
1 
1 
1 
0 
24 
0 

22 
1 
1 
1 
0 
22 
0 

28 
2 
1 
0 
1 
0 
28 

19 
2 
1 
0 
1 
0 
19 

23 
2 
1 
0 
1 
0 
23 
This model estimates a separate intercept and a separate slope for X
within each level of A
.