Welcome to MM570Welcome to MM570Psychological StatisticsPsychological Statistics

Welcome to MM570Welcome to MM570Psychological StatisticsPsychological Statistics

Unit 9 SeminarDr. April Judd

Factorial Design and Interaction EffectsFactorial Design and Interaction Effects

• Factorial research design• Comparing multiple means on two

independent variables (factors)

• Interaction effects• There is an interaction between two factors if

the effect of one of the factors changes for different categories of the other factor.

Factorial DesignFactorial Design• We are interested in comparing the weekly study time for

male and female students in different college majors.• By convention we will call one variable (Gender) Factor A

and the other variable (College Major) Factor B.• Three Null Hypotheses

• There is no difference in study time between different college majors (Green)

• There is no difference in study time between females and males (Yellow)

• There is no interaction between college major and gender on study time (Blue)

Factorial Research DesignFactorial Research Design

College Major

Male FemaleFactor B Means

Business 10.4 9.7 10.5

Psychology 8.7 6.9 7.8

Nursing 12.9 14.5 13.7

IT 10.5 8.45 9.475

Factor A Means

10.625 9.8875 10.25625

ANOVA Table for Two-Way ANOVAANOVA Table for Two-Way ANOVA

Using SPSS Factorial ANOVAUsing SPSS Factorial ANOVA Analyze General Linear Model Univariate On the Dependent variable and move it to the "Dependent Variable" box On the Independent variables (grouping variables) and move them to the "Fixed Factors" box Post Hoc and move any variable that has more than two levels to the "Post Hoc Tests For" box and select Scheffe. Plots and put one independent variable on the horizontal axis (the one with the most levels) and the other independent variable into the "Separate Lines" box, ADD Continue Options and move the variables (including the interaction) to the "Display Means for" box and check the box by Descriptive Statistics Continue OK

Using SPSS Factorial ANOVAUsing SPSS Factorial ANOVA

Using SPSS Factorial ANOVAUsing SPSS Factorial ANOVA

Using SPSS Factorial ANOVAUsing SPSS Factorial ANOVA

Using SPSS Factorial ANOVAUsing SPSS Factorial ANOVA

SPSS Factorial ANOVA Output-ANOVA Summary Table

SPSS Factorial ANOVA Output-ANOVA Summary Table

SPSS Factorial ANOVA Output-Descriptives

SPSS Factorial ANOVA Output-Descriptives

SPSS Factorial ANOVA Output-Post Hoc Comparisons

SPSS Factorial ANOVA Output-Post Hoc Comparisons

SPSS Factorial ANOVA Output- Plots SPSS Factorial ANOVA Output- Plots

InterpretationInterpretation• Females study more if they are Psychology or IT

• Males study more if they are Psychology or Nursing majors.

• There is no difference in the study time between males and females majoring in Psychology

QUESTIONS??QUESTIONS??