Originally Posted by

**Disvengeance**
It may be useful if you explicitly stated your hypothesis for this study.

Based on what you described, a two-way repeated measures ANOVA seems appropriate, assuming you checked the necessary assumptions. For your other questions regarding the two-way ANOVA, I think you need to clarify what type of sums of squares you are using. I'm also curious why you "normalized" the measures to the first measure instead of just including each measure in the model.

There are several possible types of interactions. Essentially, an interaction occurs when a variable in one group changes relative the other group. For example, you provide men and women with a treatment over time, and the treatment causes a variable to increase in men but not change in women. You can create an interaction plot to detect this visually and see if you should test for a significant interaction. Sometimes the main effect is analyzed in the presence of an interaction, depending on the interest of the researcher.