tl;dr When you have a time-varying covariate you’d like to add to a multilevel growth model, it’s important to break that variable into two. One part of the variable will account for within-person variation. The other part will account for between person variation. Keep reading to learn how you might do so when your time-varying covariate is binary. I assume things. For this post, I’m presuming you are familiar with longitudinal multilevel models and vaguely familiar with the basic diff...
