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 4.12).
Table 4.12: Example of Continuous-Nesting-Class 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.