Hello everyone, I am a researcher and wrestling with a trimodally distributed data that I want to enter into a repeated measures ANOVA (whose residuals are normal after some outlier removals). I have the suspicion that the multimodal means are masking some effects by adding variability. By the way a different variable can group the participants according to their different means. My inclination is to z-score ((x-μ )/ σ) using the the SD of the whole group, but subtract the mean according to the different variable. I've never read about this being done, so my question is, is that a legitimate approach? Or totally bogus?