# paired t-test for multiple groups

I have had a particular problem that I haven't been able to solve.

Here is the scenario: I would like to perform a paired t-test of sorts on multiple groups. Instead of before and after conditions, there are multiple conditions (ex: treatment 1, treatment 2, treatment 3 etc). Each subject appears in each 'group'. I have tried to use ANOVA, but this method averages data of all subjects within each condition, then compares their means. However, I would like to look at the differences of individual subjects between the conditions, and compare those between subjects. To me, it sounds like a paired t-test for of 2+ groups. I am using n=4. I hope that makes sense.

thanks for any input

• Can you describe the study design better? Is this a cross-over design? An AB design? Pre-post randomized design for differences in differences? Dec 20, 2016 at 2:41
• Have you heard of MANOVA (multivariate analysis of variance. For each subject you have a k dimensional vector k=4 in your case. I think this will let you include all the results for the patients in a single vecotr. Dec 20, 2016 at 2:46
• Thanks for the reply. I'm not sure what the proper terminology is. Currently, it is two sets of paired t-tests, but using the same n=4 overall. It compares scores of conditions A vs B and C vs D (all using the same unit of measurements). But now I want to compare A & D and C & B as well. My options as far as I can see are reusing the data two make four graphs (I'm hesitant about this) or perhaps combining all 4 sets on the same graph (but I'm not sure how to mathematically compare them). Dec 20, 2016 at 2:51
• In the usual ANOVA that sounds like testing contrasts. This can be done but whenever you do this you need to take account of the multiple testing and adjust p-values. Dec 20, 2016 at 3:12