In the fixed effects model with interaction, assume that there are 5 levels of factor A, 4 levels of factor B, and 3 observations (replications) for each of the 20 combinations of levels of the two factors. Then the number of degrees of freedom of the interaction sum of squares (SSAB) is
A) 60
B) 20
C) 15
D) 12
E) 59

Question

Quizplus · Accepted Answer

The formula for the degrees of freedom of the interaction sum of squares in a fixed effects model with interaction is dfAB = (a-1)*(b-1)*n, where a is the number of levels of factor A, b is the number of levels of factor B, and n is the number of replications. Substituting the values given in the question, we get dfAB = (5-1)*(4-1)*3 = 12. Therefore, the correct answer is D.

In the Fixed Effects Model with Interaction, Assume That There