This isn’t necessarily a Stata specific question, but one that seems like it would still be relevant to the broader community nonetheless.

After reviewing a couple of texts on the subject of mixed effects models (i.e., Raudenbush & Bryk, 2002; Rabe-Hesketh & Skrondal, 2012) it seems that model identification is not discussed much if at all for mixed effects models; there were no index entries in the first reference above and only a single reference in the later. So, I was wondering if anyone in the Stata community knew of any commands, papers, or procedures that one could use to determine whether or not their model is identified?

Raudenbush, S. W., & Bryk, A. S. (2002). Hierarchical linear models: Applications and data analysis methods. New York City, NY: Sage Publications Inc

Rabe-Hesketh, S., & Skrondal, A. (2012). Multilevel and longitudinal modeling using Stata. 3rd Edition. College Station, TX: Stata Press.