Two-way ANOVA

Question 1

What is the basic process of the two-way ANOVA?

Answer 1

It is very similar to conducting two one-way ANOVAs but we have the new concept of interaction to include, which is the multiplicative influence of the two independent variables acting in combination.
It requires interpretation and must be done carefully.

Question 2

What are the Main Effects in regards to the two-way ANOVA?

Answer 2

This is the effect of one IV on its own, ignoring the other IV.

Question 3

If a two-way ANOVA is described as a 2x3 ANOVA, what is it?

Answer 3

It has two IV and one had 2 levels and the other has 3 levels.

Question 4

What are interaction effects?

Answer 4

This refers effects to the combined effects of the two variables. It occurs when the effect of one of your variables is different at different levels of the other variable. This shows that the combined effects of the two IVs in that condition cannot be simply explained by the main effects of the IVs.
Interaction is what remains after removing the error and main effects

Question 5

How to conduct the two-way ANOVA?

Answer 5

We assume variance comes from four sources.
Error
Main of one IV
Main effect of second IV
Interaction of both IVs.
The first three sources are computed the same way as they were in the one-way. But we do it separately for each independent variable. (Like two separate one-way ANOVAs)

Question 6

How do we calculate interaction effects?

Answer 6

First we subtract error scores from our original scores (each score changes to cell mean)
Then we remove one IV scores. E.g. Testing gender and iron supplements for depression. We would remove our male row mean from our male scores and the female row mean from the female scores.
Then we subtract the second IV scores.

If we are left with some individual scores then there is an interaction as there is some variance left are error and main effects have been eliminated.

Question 7

How do we calculate the two-way ANOVA in spss?

Answer 7

Analyze - general linear model - univariate -

Question 8

What is a two-way ANOVA?

Answer 8

It is an ANOVA that is used when the research is looking at the effect of two independent variables on one dependent variable. It can show how the two independent variables combine to influence dependent variables scores.
Main effects are the influence of independent variables acting separately.
Interaction is the influence of the independent variables acting in combination.