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Is there a way to perform a confirmatory GGMM? If my theory makes specific hypotheses about trajectory groups, can I put in the model specifications apriori and then test them against an unrestricted model? I tried this and failed miserably, and I'm not sure why  if my model specifications were written incorrectly, if what I tried to do is impossible, or if the model really didn't fit. I was trying to replicate someone else's findings with my data. Guo et al (2002) found a 4 group model for marijuana use trajectories: (1) early high, (2) escalator, (3) late onsetter, (4) nonuser. I tried to replicate these group patterns by using model constraints. First I labeled all the parameters I wanted to constrain: %c#1% [i] (a); [s] (b); [q] (c); %c#2% [i] (d); [s] (e); [q] (f); %c#3% [i] (g); [s] (h); [q] (i); %c#4% [i] (j); [s] (k); [q] (l); Model Constraints: b >0; c < 0; f >0; 0 < i < f; a=0; b=0; c=0; It came up with a computing error. I also tried estimating it without any of the constraints and then put in constraints that matched what the unconstrained model found and it didn't work either. What am I doing wrong? Thanks!!! 


I think the error is likely from 0 < i < f; Confirmatory with inequalities may be difficult to do. I would just do an exploratory analysis and see if I find the same classes. 


Thanks!! 

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