# Post hoc analysis after two-way repeated measures ANOVA

I am measuring test performance at 10 different timepoints, before and after drug application.

So far I ran two-way repeated measures ANOVA and determined there is a significant timepoint, drug, and timepoint*drug effect.

We are particularly interested whether the test performance is different between the control and drug group at timepoints 1, 5 and 10.

I have been considering testing these three timepoints separately using paired t-test for each. I was wondering if that is an appropriate approach? Is it necessary to control for multiple comparisons? Which tests would be most suitable?

If you have 10 time points then performing individual t-tests on each pair will get very annoying very fast. And yes, you do need to adjust for multiple comparisons. This is usually done with a GLMM (Generalized Linear Mixed Model), one model which would perform all this in one step. In case you are using R, you can use the nlme or lme4 packages.