Shared Statistical Concepts


Continuous-by-Class Effects

Continuous-by-class effects generate the same design columns as continuous-nesting-class effects. Table 4.13 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 4.12.

Table 4.13: Example of Continuous-by-Class Effects

Data

 

I

 

X

 

A

 

X*A

X

A

 

$\beta _0$

 

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.