1. 11. Experimental Research: Factorial Design
What are factorial experimental designs, and what advantages do
they have over one-way experiments?
What is meant by crossing the factors in a factorial design?
What are main effects, interactions, and simple effects?
What are some of the possible patterns that interaction can take?
How are the data from a factorial design presented in the research
reports?
What is a mixed factorial design?
What is the purpose of comparing means, and what statistical
techniques are used to do this?

2. Factorial Experimental Designs
Experimental designs with more than one independent variable.
The term factor refer to each of manipulated independent variables.
2 Factors
Example. IV. Sex (male, female),
Ethnicity (Black, White, Asian, Latino)
DV. Self-esteem
4 levels
2 levels
Black White Asian Ratino M F
Cells
2  4 designs

3. The Two-Way Design
Example. Violent cartoons and children’s frustrated state increase
their aggressive behavior.
IV: Violent Cartoons vs. Nonviolent Cartoons
Frustrated State vs. Non Frustrated State
DV: Children’s aggressive behaviors.
Violent Nonviolent
Frustrated
Not
frustrated
Av. M = 2.97
Av. M = 3.90
M = 2.68 N= 10
M = 3.25 N= 10
M = 5.62 N= 10
M = 2.17 N= 10
Av. M = Av. M = 2.71

4. Main Effects, Interactions, and Simple Effects
The effect of each factors
Main Effects
The effects in which the influence of one factor on the DV is different at different levels of another factors.
Interactions
Simple Effects
The effect of one factor within a level of another factor
Violent Nonviolent
Frustrated
Not
frustrated
Av. M = 2.97
Av. M = 3.90
M = 2.68 N= 10
M = 3.25 N= 10
M = 5.62 N= 10
M = 2.17 N= 10
Av. M = Av. M = 2.71

5. ANOVA Summary Table Source Sum of df Mean F p-value Squares Square DV:
Aggressive
Play
Cartoon *
Prior State
Cartoon by
Prior State *
Residual
Total

6. Chart
Cartoon
Residual
Prior
State
C & PS

7. Understanding InteractionsDV DV DV
Frustrated
Nonfrustrated
Violent Nonviolent
Violent Nonviolent
Violent Nonviolent
Patterns with Main Effects Only

8. Understanding InteractionsDV DV DV
Frustrated
Nonfrustrated
Crossover Interaction
Violent Nonviolent
Violent Nonviolent
Violent Nonviolent
Patterns with Main Effects & Interaction Only

9. Interpretation and Presentation of Main Effects and Interpretations
2 (cartoon)  2 (prior state) ANOVA was conducted. The
results indicated that there were significant main effect of cartoon,
F (1, 38) = 4.45, p < .05. Children who viewed the violent
cartoon (M = 2.89) were rated as playing more aggressively than
children who had viewed the nonviolent cartoon (M = 1.52). This
main effect, however, should be qualified by the interaction with
prior state, F (1, 36) = 4.42, p < .05. Children who were frustrated
and viewed the violent cartoon (M = 5.55) were rated as playing
more aggressively than children in other conditions (M = 1.11, 1.48,
1.54, respectively).