OpenMx General Help

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Picture of user. rabil Joined: 01/14/2010

Should the degrees of freedom depend on how the data are input?

I'm running OpenMx 1.0.2 on Ubuntu 10.04. OpenMx shows the degrees of freedom differently for using raw data than for using the covariance matrix (and means vector). The model has one factor with 6 indicators and 9 parameters are being estimated (some parameters are constrained to equal other parameters).

Here is the output for the raw data:

observed statistics: 120
estimated parameters: 9
degrees of freedom: 111
-2 log likelihood: 894.0595
saturated -2 log likelihood: NA
number of observations: 20
chi-square: NA
p: NA
AIC (Mx): 672.0595
BIC (Mx): 280.7666

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No user picture. dadrivr Joined: 01/19/2010

Obtaining fit indices (CFI, RMSEA, etc.) with FIML

Is it possible to obtain fit statistics such as CFI, RMSEA, etc. with FIML? The model I'm currently running does not output the desired fit indices (see below). After reading some of the threads, it appears that I would need to use FIML estimation to fit a saturated model, and then compare the predicted model to the saturated model. Is that correct? Could someone explain a little more how to do that? Sorry, I'm new to OpenMx. Thanks so much for your help, and I love the program so far!

Here's the output from my model:
observed statistics: 276
estimated parameters: 23

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Picture of user. Mike Cheung Joined: 10/08/2009

Versions 0.9.0 vs. 0.5.2

Hello all,

I am fitting some variance known models (akin to meta-analysis). To handle models with possible covariates, I use a RAM model. The results based on 0.5.2 are comparable to those based on other statistical packages. After upgraded to 0.9.0, the results look odd.

The followings are an example. The -2LL of the 0.5.2 and 0.9.0 versions are 27.79916 and 29.02565, respectively. Any suggestions are highly appreciated. Thanks.

Regards,
Mike

yi <- c(-0.264,-0.230,0.166,0.173,0.225,0.291,0.309,0.435,0.476,0.617,0.651,0.718,0.740,0.745,0.758,0.922,0.938,0.962,1.522,1.844)

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No user picture. joespher Joined: 07/28/2010

what's the estimator in OpenMx?

Dear all:
I'm a new learner of OpenMX and R , I want to use it to do simple SEM analysis, but I can't find the estimator information in OpenMxUserGuide. please tell me how can I find and how can I understand the estimator in OpenMx .
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Picture of user. mspiegel Joined: 07/31/2009

parameters of 1 factor factor examples

I'm posting a link to a comment from one of the news updates, because those comments appear without a listing in the "Recent Threads" panel on the right-hand side of the page.

http://openmx.psyc.virginia.edu/2010/08/openmx-050

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No user picture. rlucas Joined: 11/17/2009

Should version 0.5 be slower on some models?

I have been running some models that decompose multi-wave data into a stable trait component, an autoregressive trait component, and a state component. I have eight waves, with three indicators at each wave, 600 observations, and I'm using raw data (and there are missing data). With the data I have, these models (and some variants) can take a little while to run. But I've noticed that they actually run considerably slower with version .5.0 than with .3.0 (I hadn't upgraded until .5.0 came out).
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Picture of user. Mike Cheung Joined: 10/08/2009

Jacobian matrix

Hi,

I am trying to implement the Satorra-Bentler robust standard error. It requires the Jacobian matrix in the calculations. Apparently, the Jacobian matrix is called "cJac" in npsolWrap.c. I would like to see whether it is possible to access "cJac" in OpenMx. Thanks in advance.

Regards,
Mike

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No user picture. pjohnson Joined: 09/19/2009

Can you give me simple, self contained working examples for testing parallel OpenMX

I'm not an OpenMx user, but I am trying to help somebody who is. We want to parallelize OpenMX models, sending them across many compute nodes in a Linux cluster. We can run with Rmpi or SNOW. (I see you support snowfall's approach to multicore, but I mean parallelization across many computers. We can run programs using snow, but not snowfall is not allowed (incompatible with OpenMPI)).

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Picture of user. Sanja Joined: 12/07/2009

How to cite OpenMx?

Sorry to open a topic just for this, but how do I cite the OpenMx software? (not the manual, I've got a ref for that)
Thanks,
Sanja
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No user picture. wcyee Joined: 08/02/2010

Trying a LISREL example in OpenMx

Taxonomy upgrade extras
Hi, I haven't used OpenMx before, but I started by trying an example from the LISREL book (Joreskog & Sorbom).

I've reproduced the LISREL sample below and my translation to OpenMx based on reading the beginners section in the help. The error message I get is:

"Error: The job for model 'ex6' exited abnormally with the error message: Backing out of parameter space region where expected covariance is non-positive-definite."

I'm probably doing something silly here. Any help much appreciated!

======= lisrel code ========

Stability of Alienation
Observed Variables