Lecture 6- Factorial Analyses of variance

Question 1

When is a 2x2 anova used

Answer 1

When there are 2 factors, with 2 levels, and 1 DV

i.e. Age, Gender measuring maths score.

Question 2

What are the main effects

Answer 2

The main effect is when you ignore one of the factors and compare the marginal means of the two levels of one factor.

Question 3

What is the interaction

Answer 3

It is assessing whether there is a difference between factor 1 levels 1 and 2 compared to factor 2 levels 1 and 2.

Question 4

When are follow up tests needed

Answer 4

when there is a significant interaction

Question 5

How do you report a 2x2 anova

Answer 5

1. Report what was done:
   A 2x2 Factorial anova was conducted on factor 1 (levels 1 and 2) and factor 2 (levels 1 and 2).
2. Report main effect for 1 factor and marginal means:
   Results showed that there was a significant main effect for factor 1 on DV F(df1, df2) = , p= .
   Overall level 1 had a higher dv (marginal mean = ) than level 2 (marginal mean= )
3. Report main effect for factor 2 and marginal means:
4. Report the interaction
5. If the interaction is significant conduct 4 bonferroni corrected post hoc tests

Question 6

How do you know if it is a between or within pps factorial anova

Answer 6

A between pps factorial anova has different pps for each of the different levels.

Question 7

How do you run a between pps factorial anova in spss?

Answer 7

1. Split the file for one of the variables
2. Get the descriptive stats
3. unsplit before you run the anova
4. run anova :
   analyse- general linear models- univariate.
   when doing the t tests:
5. split file by 1 factor
6. conduct t tests on the levels of the other factor.

Question 8

when using atable for the mean score does the title go at the top of bottom

Answer 8

Top.

Table 1: mean scores for (SD in brackets)