Factorial Designs

Question 1

What are the requirements for a factorial design?

Answer 1

At least two factors (IVs) with at least two levels that can be examined simultaneously (crossed)

Question 2

What is a factor?

Answer 2

A categorical variable with at least two levels

Question 3

What is a main effect?

Answer 3

The effect of one factor averaging across the levels of another factor

Question 4

What is an interaction?

Answer 4

When the effect of one factor depends on the level of another factor

Question 5

How are main effects identified?

Answer 5

By looking at the differences between the marginal means of a factor

Question 6

When are follow-up tests needed when comparing marginal means?

Answer 6

When there are more than two marginal means, to find where differences lie

Question 7

How are interactions identified?

Answer 7

By comparing the simple effects between factors

Question 8

How are simple effects identified?

Answer 8

By looking at the differences between the cell means at each level of the focal IV

Question 9

What are advantages of factorial designs?

Answer 9

1. They are economical in terms of participants
2. They allow examinations of an interaction and the generalisability of an effect

Question 10

What is the correct notation for a between- participants factorial design?

Answer 10

(No. of levels in Factor A * No. of levels in Factor B) between-participants factorial design

E.g. 2*3 between participants factorial design