General SEM Discussions

Hi,
Are there any example scripts for how to add a definition variable to a RAM model, and how to then use that in an algebra on a path?

Here's one adding a definition variable for means, but not including its value in an algebra, and then using that algebra to se the value for another path.

[https://openmx.ssri.psu.edu/docs/OpenMx/2.5.1/DefinitionMeans_Path.html](https://openmx.ssri.psu.edu/docs/OpenMx/2.5.1/DefinitionMeans_Path.html)

Hi,

Could we run a bivariate heritability analysis using twin data when one of two traits has a best model ADE or DCE and the other ACE?
Two main phenotype seems to be more ADE for one and DCE model for the other and I compare them with other phenotypes with different best model.
One of my colleague has kindly provided to me her script but it runs only when the two traits have a best model type ACE.

I know that Ra, Rd could be null as one of my phenotype didn't have it in its best model. It is fine, but at least the model for each trait is the best.

I have a question, which I closely related to an earlier question of me (http://openmx.psyc.virginia.edu/thread/3991). Given a longitudinal SEM model, which has been fitted using many persons, is there a recommended approach to obtained person-specific predictions for unobserved time-points, as there is for obtaining factor scores? (see e.g http://www.tandfonline.com/doi/abs/10.1080/00273171.2012.730072 by Ryne Estabrooka & Michael Neale).

Hello,

I am relatively new to OpenMx. I am wondering if it's possible to compute a profile likelihood CI using OpenMx. I saw the documentation for mxCI(), but I would appreciate if one can provide OpenMx code to estimate a profile Likelihood CI for mediated effect in single mediator model with all observed variable.

I also saw Pek, J. & Wu, H. (2015) article, but it appears that mxCI() can implement their approach, if I am correct.

Thanks for your time in advance,

Davood

Hi all,

Does anybody know a reference in which it is shown that the likelihood ratio test statistic converges to a Chi squared distribution for extended SEMs with definition variables?

With extended SEM I mean RAM models where the entries of A and S may be arbitrary algebras. In contrast to classical SEM where the entries of A,S are either fixed or a single parameter. With definition variables I mean that any fixed value in an SEM may be replaced by a person specific value such that it is different for every person.

Hi,

I am making a 2-steps approach to estimate a SEM model in the field of economics as depicted in the attached figure. In order to obtain the estimated values of the latent variables observation-by-observation for N=142 countries in the 1st step I am using the predict function of lavaan.

Whilst fit results for the individual measurement models of the 1st step are pretty good, at the moment I have not got acceptable RMSEA and TLI in the 2nd step (RMSEA: 0.245, TLI: 0.897) as shown in the following chart:

RMSEA CFI TLI SRMR
1st step