#7 Step 6: Factorial Design

Question 1

What is a factorial design?

Answer 1

Factorial design is a research design that includes 2 or more independent variables.
- Described by no. of variables e.g. 2-factor design or 3-factor design

Factor 1 - hairstyles (straight or curly)
Factor 2 - face shapes (oval, round, square)
Factor 3 - hair length (short, long)
2x3x2 factorial design

Question 2

Why not look at these factors separately?

Answer 2

1. See the unique contribution of each factor (main effect)

2. Interaction between factors to influence behaviour (interaction effect)

Question 3

What is the main effect?

Answer 3

The effect of a single independent variable on the dependent variable, ignoring all the other IVs

Question 4

What is the interaction effect?

Answer 4

An interaction that exists between factors when the effects of one factor depend on the level of the second factor

Question 5

How do you check the interaction effect?

Answer 5

1. Look at the table and check for the simple effect of each factor.
   - Simple factor = the effect of one IV within one level of another IV
   - if the simple factor is the same, there is no interaction
2. Look at the line graph
   - Parallel lines: no interaction
   - Non-parallel lines: interaction
   - need to do a statistical test to determine whether the interaction is significant

Question 6

What is important to note when understanding and interpreting main factor/interaction?

Answer 6

Main effects and interaction are completely independent of one another

Question 7

Types of interaction

Answer 7

1. Ordinal interaction: lines do not cross (suggests a greater difference between groups at one level of a factor than at the other level of the same factor)
2. Disordinal factor: lines meet (interaction of main effects is likely to be misleading, need to check the main effect vs simple effect)

Question 8

What is moderation?

Answer 8

Occurs when the relationship between 2 variables (IV and DV) change as a function of the 3rd variable
- implies an interaction effect, where the introducing moderator changes the direction/magnitude of relationship between 2 variables

Question 9

Types of factorial design

Answer 9

1. between-subject factorial design
2. within-subject factorial design
3. mixed-design factorial