OpenMx General Help

Posted on
No user picture. CharlesD Joined: 04/30/2013

matrix logarithm function for mxAlgebra

Any chance of this being implemented at some point? Would seem to be consistent with the omxExponential implementation. Currently I optimize some free parameters over the range 0 to -inf, which is exponentially scaled, and I suspect this probably poses optimization difficulties....
Posted on
No user picture. metavid Joined: 06/23/2014
Posted on
No user picture. yoosoo Joined: 06/19/2014

Does OpenMx support multilevel, ordinal/binary outcomes/indicators with sampling weights?

Hi,

I am hoping to perform a multilevel SEM on complex-sampling survey data, with known weight and binary outcome and ordinal independent variables.

Similar posts on this forum don't seem to support that this is simple to do on OpenMx, but any advice would be much appreciated. (http://openmx.psyc.virginia.edu/thread/2348, http://openmx.psyc.virginia.edu/thread/861#comment-form)

Thank you.

Posted on
No user picture. jkarch Joined: 03/15/2011

Obtain number of Objective function evaluations

Hi,

I am interested in obtaining both the number of major iterations and the overall number of objective function evaluations (how many times is the log likelihood and its gradient computed).
I found model@output$iterations and model@output$evaluations. model@output$iterations is the number of major iterations. model@output$evaluations contains a vector with two integer entries. Does somebody know what the entries are?

Posted on
Picture of user. siti nur azizah Joined: 03/12/2014

modified model

hi, I am a beginner using Mx open packages, so I do not quite understand. I have run my program. output is given as attached.
The value of RSMEA, CFI and TLI its very ugly because its value doesn't meet either criteria . What can I do in advance to improve the model?
thank you.
Posted on
No user picture. mverdam Joined: 02/04/2014

Referring to an OpenMx matrix in the OpenMx environment

I'm trying to run a model in which I have several matrices that should contain the same parameter estimates (they overlap partly). I know I can use labels or mxConstraint to put equality constraints on parameter estimates, but I was wondering if it is also possible to refer directly to the parameter estimates of a matrix in other parts of the OpenMx environment. For example, I have tried to build an mxAlgebra that refers to the parameter estimates of an mxMatrix by using:

mxAlgebra(expression=cbind(Model.mxMatrix[,i],Model.mxMatrix[,j]), name="part_mxMatrix")

Posted on
No user picture. fife Joined: 07/01/2010

Computing R squared with missing data

This may be an easy question, but I can't think of the answer. I've built a regression model (predicting Y) with two independent variables (X and Z). I want to compute R^2. Is that built into the model somehow? If not, any ideas on how to compute it? Here's the model I have:

multiRegModel <- mxModel("Multiple Regression, All Variables",
type="RAM",
manifestVars=c("x", "y", "z"),
# variance paths
mxPath(
from=c("x", "y", "z"),
arrows=2,
free=TRUE,
values = c(.5, .5, .5),
labels=c("varx", "residual", "varz")
),

Posted on
No user picture. a9mike Joined: 06/28/2013

Confidence Intervals

I'm not sure the best way to get confidence intervals for my estimates. I'm doing a bifactor model with a large dataset (HRS) with lots of missing data, and the mxCI are taking impossibly long (days long).

Anyone have suggestions? Would bootstrapping be faster? If so, what would that script look like? (I've never bootstrapped before)

Posted on
No user picture. cuttance Joined: 01/20/2014

OpenMx in the Cloud

I’m looking to integrate MSEM (one of: OpenMx, MPlus, LISREL, etc) into an application I am developing for schools on a .NET Microsoft Azure Cloud platform — multiple schools will access the application simultaneously, and the application will call the MSEM modelling unit to estimate a specific model and return the estimates to a database for benchmarking purposes.

Would I need to run OpenMx inside a VM, or is there a server version? Can multiple instances of OpenMx run inside the same VM? or Would we need to run multiple VMs, each for an instant of OpenMx?

Posted on
No user picture. c3094213 Joined: 12/30/2013

Genetic correlation equals to 1 or -1 in Bivariate ACE model

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?