Week Four - Two-Factor ANOVA

Question 1

What is a Two-Way ANOVA

Answer 1

A design with two IV (A and B) with each of these IV’s having two or more levels

a x b design

Question 2

What does a TWA assess?

Answer 2

How the two variables interact to affect the DV

Question 3

When do we assess marginal means and cell means?

Answer 3

Marginal means in main effects

Cell means in interaction

Question 4

How can a significant/non-sig interaction be interpreted?

Answer 4

The main effect for one IV is not/is the same at all levels of the other IV

Question 5

What do main effects ask us?

Answer 5

Whether there is a real difference in MM, regardless of one IV

Question 6

What does a TWA give us?

Answer 6

2 main effects and an interaction effect

Question 7

What do you do when you have a significant main effect (or two)?

Answer 7

If there are only two levels of each IV, no further tests required.

If more than two levels of IV, follow-up tests required e.g., Tukey or BA t-test

Question 8

What do you do when you have a significant interaction?

Answer 8

Over-rides main effect (so don’t need to do follow ups on main effects if sig and more than two levels).

Need to do tests of simple main effects with BA to clarify interaction (examining the effects of one factor at separate levels of the second factor)