Week 4 Flashcards
In a two way ANOVA testing the marginal means for 2 IVs and the interaction, what alpha adjustments do we have to do?
None - it is still only 5% likely that the results are due to chance because they get tested at the one time.
How do we follow up a significant interaction in a two way ANOVA?
use tests of simple main effects
What is a test of simple main effect?
involve examining the effects of one factor at separate levels of the second factor.
Each tests of simple main effects needs:
follow up tests
What happens if there’s a significant interaction and also a significant main effect?
The interaction overides the main effect.
If you test the simple main effect of A and there’s only 2 levels, it is:
clear where the significance is so no follow up tests are needed
If there are more than 2 levels of IV A and the simple main effect is significant, you need to
follow up with post hoc tests between cell means maintaining a Bonferonni significance level
If you have more than 2 levels of IV A and the simple main effect is significant but you don’t want to do follow up post hoc tests, what’s something else you can do?
Planned comparisons - if you wanted to do specific comparisons. HOWEVER, you still need to be aware to TYPE 1 ERRORS.
If you want to look at the individual magnitude (effect size) of each effect in an ANOVA (which Jamovi can do automatically via partial eta squared), what do you need to do?
What is the formula for this?
Divide the individual magnitude of the effect by the individual magnitude of that effect PLUS the error.
E.g.,
n^2p= SS(sum of squares)A
——————————–
SSA + SSerror
What is one issue with partial eta squares when used to look at the magnitude of an individual effect in a factorial ANOVA design?
The magnitude of each effect is not additive, i.e., it doesn’t add up to 1. SO the meaning is obscure.
