Bivariate Cholesky model with one continuous and ordinal variable

Hello Leo

I think umx will fit the model you want fairly painlessly. Note that while it doesn't have the explicit scripting that writing in 'base' OpenMx provides, umx does return OpenMx model objects, which can be inspected and modified to test submodels etc.

Another place to look is in the inst/models/passing directory of the installation (or on GitHub here: https://github.com/OpenMx/OpenMx/blob/master/inst/models/passing/JointFIMLTest.R) which has examples of joint FIML, albeit not twinified.

Just to follow up:

1. If you had "myOrd_T1" and "myOrd_T2" ordinal vars and "myCont_T1" and "myCont_T2" continuous vars in your Data, you just execute:

m1= umxACE("my model",
    selVars = c("myOrd", "myCont"), sep = "_T", 
    mzData = mzData, dzData = dzData
)

2. The nice thing about umx, is the functions are scripts. So if you just type the function name without the trailing (), then press return, you'll see all the raw matrix algebra. Plus all the code is open, commented, and editable on github.com/tbates/umx

3. You might be interested to play with umxTwinMaker It let's you build twin models using umxPaths, but you only specify twin1 - it takes care of the rest. Cuts 90% of the work. RAM runs slower, but not much, and all the plot and umxSummary inc. std run on arbitrary models (these are extra custom coding work for each new matrix based model).