I have the following problem.

i estimated a single common factor model in twin pairs:

correlated factors within twinpairs, correlated residuals between measurements done at equal timepoints within twinpairs.

now i want to model the factor means by intoducing a definition variable.

i got the single factor twin model working, which essentially is a two factor model one factor for each twin. Now i need to introduce a definition variable that influences the factor mean. I have found some MX scripts for this but i need it to work in openMX.

How to go about this. I have read all help files on both the factor models and the definition variables but found no reference on definition variables related to factor mean moddeling.