One of the most confusing things about mixed models arises from the way it’s coded in most statistical software. Of the ones I’ve used, only HLM sets it up differently and so this doesn’t apply.

But for the rest of them—SPSS, SAS, R’s lme and lmer, and Stata, the basic syntax requires the same pieces of information.

1. The dependent variable

2. The predictor variables for which to calculate fixed effects and whether those [Read more…] about Mixed Models: Can you specify a predictor as both fixed and random?