My design is a two factor 3x5 (3 hormone conditions and 5 drug conditions, 15 groups total) between-subjects ANOVA. When rats undergo the 15 minute pre-test habituation forced swim they have not been subjected to anything and thus all groups have been treated the same. Only after the pre-test are they injected with drug and hormone, and 24 hours later they were put into the forced swim test again for the 5 minute test period. Am I to analyze both the 15 minute habituation/pre-test data and the 5 minute test day data together and treat it as if it's a repeated measures test? Or is it sufficient to just analyze the test day data and to just make sure that there are no differences in the pre-test data?
I would analyze them separately if I understand your question correctly.
Hello Collin,
The answer depends on what your research question is. Unfortunately, I can't be sure from the description as it stands.
Good luck with your work.
Hello Collin,
Since the posted question has changed, so has my response!
It might make more sense to use the baseline measure (15 min data points) as a covariate, so that randomly occurring differences across groups at baseline would be accounted for in the target measure (5 min data points).
To the extent that baseline and target measure scores correlate, this will reduce the (otherwise) unexplained variation in the target scores.
Good luck with your work.
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