Need help figuring out which test to use!

Hi there!

I have a data file with the following information: pre-intervention depression score (t1), post-intervention depression score (t2), t1-t2, and grade level (Freshman, Sophomore, Junior, Senior). How can I compare t1 across grades, t2 across grades and change in depression score across grades? My best guess would be to do an ANOVA comparing t1, another ANOVA comparing t2 and a third ANOVA comparing t1-t2, but that sounds like too many tests. Is there a test that can do all of this at once (such as a two-way ANOVA)?



TS Contributor
In a repeated measures ANOVA (or "mixed" ANOVA) you can include time of measurement as within-subject factor and grade as between-subject (grouping) factor. The time*group interaction will be of partiular interest.

But if you specifically want to compare depression at baseline between groups, you'll have to perform a separate oneway ANOVA.

With kind regards