# Shared Concepts and Topics

#### Continuous-by-Class Effects

Continuous-by-class effects generate the same design columns as continuous-nesting-class effects. Table 19.8 shows the construction of the X*A effect. The two columns for this effect are the same as the columns for the X(A) effect in Table 19.7.

Table 19.8: Example of Continuous-by-Class Effects

Data

I

X

A

X*A

X

A

X

A1

A2

X*A1

X*A2

21

1

1

21

1

0

21

0

24

1

1

24

1

0

24

0

22

1

1

22

1

0

22

0

28

2

1

28

0

1

0

28

19

2

1

19

0

1

0

19

23

2

1

23

0

1

0

23

You can use continuous-by-class effects together with pure continuous effects to test for homogeneity of slopes.