OpenMx General Help

Hello All,

I had just done bivariate ACE model for two continuous variables (bivariate correlated factors model). The results turned out to be a little weird as follows:

A1 = 0.25, A2 = 0.09
C1 = 0.12, C2 = 0.08
E1 = 0.62, E2 = 0.82
Rph = -0.24
Ra = -1
Rc = 1
Re = -0.26

We observe Ra is -1, but we personally think it is not reasonable that the two variables are perfectly correlated. Is it possible that there are some problems with the program?

Hi. I've been doing some work on a package to overlay openmx and manage continuous time SEM models. Everything is working great but I am quite stuck with what seems to be some sort of memory management issue with openmx. I've spoken with Tim Brick regarding this previously, but thought I'd put it up here for all to see :)

Hello All,

First of all thank you for your hard work over the years to provide us with unique ways to combine meta-analytic principles with SEM--and providing a conduit to do this in R. My research team and I really appreciate it.

I am doing a two stage MASEM with the metaSEM package, and am having some difficulty specifying a mediation analysis in the A/Smatrix. I have four variables: w,x,y,z. And my linear equations are as follows:

X ~ W + e
Z ~ W + e
Y ~ W + X + Z + e

I would like to see if X or Z (or X and Z) mediate the relationship between W and Y.

Hello!

I use Australian twin sample biometric data to test my scripts, but there is something unclear with zygosity variable: it has 10 levels instead of 5 (as declared on help page). How should I actually interpret these levels?

So I just started learning SEM this past year, teaching myself with some guidance from my advisor. I learned on AMOS, but I'm trying to teach myself OpenMX (just started last week).

I adapted OpenMx ordinal threshold model example code to estimate a model with 5 raters using a 5-point ordinal scale. (The code uses threshold deviations.) The model converges (after some tweaking of starting values) with no errors and no warning messages - this is on a computer running Ubuntu 13.04 and the latest version of OpenMx. The same model was estimated using MPlus - both yield very similar factor loading estimates and threshold estimates (although MPlus used weighted least squares - ML wouldn't work).