Two-Factor ANOVA

Question 1

What is a factor?

Answer 1

an independent variable

Question 2

What is a two-factor ANOVA?

Answer 2

a factorial ANOVA with two factors

Question 3

What are the hypothesis tests for a two0factor ANOVA?

Answer 3

• are there differences across the levels of factor A
• are there differences across the levels of Factor B
• are there differences across some combination of levels of factor A and factor B?

Question 4

What are the possible results in a two-factor ANOVA?

Answer 4

any possible combination of significant and/or not significant main effects and interactions

Question 5

What is Stage 1 of a two-factor ANOVA?

Answer 5

total variability in the data is split into between-groups sources and into within groups variability

Question 6

What is Stage 2 of a two-factor ANOVA?

Answer 6

further partitioning the between-groups variability into its components (differences due to Factor A, B and interaction effects)

Question 7

What are main effects?

Answer 7

the effect of each individual factor on its own

Question 8

What is an interaction effect?

Answer 8

the combined effect of the factors where the effect of one factor depends on the different levels of the second factor

Question 9

What is partial eta-squared?

Answer 9

percentage of variance in DV accounted for by the effect of interest

Question 10

When do you conduct post-hoc tests?

Answer 10

when there are no interaction effects at all

Question 11

What do you do when there are interaction effects present?

Answer 11

only interpret the interaction by line graphs and marginal means tables

Question 12

What are the assumptions of two-factor ANOVA?

Answer 12

• independent observations
• normally distributed
• homogeneity of variances

Question 13

Why do we not conduct post-hoc tests to interpret a main effect when both the interaction and main effect are significant?

Answer 13

the main effect is further explained by or depends on the interaction effect