Lecture 8 - 2x2 factorial anova - Split plot Flashcards
When is it used?
When there is 2 factors, 2 levels, 1 dv.
One of the factors is a within subject variable, one factor is a between subject variable.
What does the interaction actually assess
I assesses two levels of one factor in one of the levels of the other.
Is the intercation in the spss output included in the within or between subject output?
The interaction is included in the within subject output because it includes a within subject element.
The definition of sphericity ?
A measure of whether the variance of the differences between any 2 levels is equal, cant be done with only 2 conditions.
When do you do the follow up tests
when the interaction is significant.
How to report a split plot anova:
- What was done :
A 2x2 split plot anova with 1 factor of (levels) and another of (levels) was conducted. - Report the first main effect:
The results showed that there was a significant main effect of [Factor #1] on [DV] (F(df1, df2) = [F value], p = [p value],ηp2 = [partial eta squared value]). - Report the marginal means
Overall [Factor #1 Level 1] had a higher [DV] (Mean = [Factor #1 Level 1 marginal mean value]) than [Factor #1 Level 2] (Mean = [Factor #1 Level 2 marginal mean value]). - Repeat for the second factor.
- Report the interaction :
In addition there was a significant interaction between [Factor #1 and Factor #2] on [DV] (F(df1, df2) = [F value], p = [p value],ηp2 = [partial eta squared value]). - Report t tests
How to run the anova in spss
Three columns: The between pps variable with 1 and 2.
The other columns show the within pps score.
1. When running the explore, the between pps variable should be in the factor list. ANd the dependents should be together
2. Analyse - general linear model- repeated measures
How to run the t tests on a split plot data set
- Split the file by the between pps factor - groups. The run the paired t tests.
- Unsplit the file- run the independent t tests
