11. experimental research: factorial design
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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? - PowerPoint PPT PresentationTRANSCRIPT
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?
Factorial Experimental DesignsFactorial Experimental Designs
Experimental designs with more than one independent variable.The term factor refer to each of manipulated independent variables.
Example. IV. Sex (male, female), Ethnicity (Black, White, Asian, Latino) DV. Self-esteem
M
F
Black White Asian Ratino
4 levels
2 levels
20 24 19 20
24 18 20 21
Cells
2 4 designs
2 Factors
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 StateDV: Children’s aggressive behaviors.
Frustrated
Not frustrated
Violent Nonviolent
M = 2.68 N= 10 M = 3.25 N= 10
M = 5.62 N= 10 M = 2.17 N= 10
Av. M = 4.15 Av. M = 2.71
Av. M = 2.97
Av. M = 3.90
Main Effects, Interactions, and Simple Effects
Frustrated
Not frustrated
Violent Nonviolent
M = 2.68 N= 10 M = 3.25 N= 10
M = 5.62 N= 10 M = 2.17 N= 10
Av. M = 4.15 Av. M = 2.71
Av. M = 2.97
Av. M = 3.90
Main Effects
Interactions
Simple Effects
The effect of each factors
The effects in which the influence of one factor on the DV is different at different levels of another factors.
The effect of one factor within a level of another factor
ANOVA Summary Table
Source Sum of df Mean F p-value Squares Square
DV:AggressivePlay
Cartoon 23.56 1 23.56 4.56 .04* Prior State 11.33 1 11.33 2.00 .17 Cartoon byPrior State 29.45 1 29.45 5.87 .03*
Residual 41.33 36 5.17 Total 94.67 39 59.51
Chart
Residual
Cartoon
PriorState
C & PS
Understanding InteractionsDV DV Frustrated
Nonfrustrated
Violent Nonviolent Violent Nonviolent
Patterns with Main Effects Only
DV
Violent Nonviolent
Understanding InteractionsDV DV Frustrated
Nonfrustrated
Violent Nonviolent Violent Nonviolent
Patterns with Main Effects & Interaction Only
DV
Violent Nonviolent
Crossover Interaction
Interpretation and Presentation ofMain 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 violentcartoon (M = 2.89) were rated as playing more aggressively than children who had viewed the nonviolent cartoon (M = 1.52). Thismain 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).