A researcher used an ANOVA to compare four treatment conditions with a separate sample of n=12 participants in each treatment, for a total of N=48 participants. The results of the analysis are shown in the following summary.
Source SS
Between-treatments 15
Within-treatments 88
Total 103
What is MSbetween?
To find MSbetween (Mean Square between), you need to divide the sum of squares (SS) for the between-treatments condition by the degrees of freedom (df) associated with the between-treatments condition.
MSbetween = SSbetween / dfbetween
In this case, the sum of squares for the between-treatments condition is given as 15. However, the degrees of freedom for the between-treatments condition is not provided. To calculate the degrees of freedom, you need to subtract 1 from the number of treatment conditions.
In this case, there are 4 treatment conditions, so the degrees of freedom for the between-treatments condition would be (4 - 1) = 3.
Therefore, you can now calculate MSbetween using the given information.
MSbetween = SSbetween / dfbetween
MSbetween = 15 / 3
MSbetween = 5