OpenMx General Help

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No user picture. EmilieRH Joined: 09/24/2020

Bivariate ACE model with moderator

Hi all,

I am currently working on a project on how school achievement moderates intelligence among young adults. My sample consists of 4,084 German twins aged 17 and 23-24, respectively, who have information on both GPA and intelligence. However, the twins' GPAs come from various types of secondary schools so to check whether I need to use school type as a moderator in my GxE analyses, I first want to see what happens if I run separate bivariate variance decomposition analyses for the three school types constraining their parameters equal.

Posted on
No user picture. PCFLaw Joined: 08/26/2020

2-class growth mixture model: adding time-invariant covariates & viewing class probabilities

Hi,

I am wondering if I can get some help on a 2-class growth mixture model I'm having trouble with (script and example dataset attached). The model describes a single linear trajectory across 8 time-points (t1-t8). I'm new to OpenMx and I've looked through this forum/other sites but I'm at a loss. I'm trying to (i) add 3 time-invariant covariates ('Sex', 'Age', 'pooled_VA') to the 2-class growth mixture model and (ii) view the class probabilities for each case.

Posted on
Picture of user. davide Joined: 03/13/2020

Constraints

Hi Open Mx Folks

I'm trying to construct a model where I need to implement a constraint across groups. My model is of the form:

Mxgroup1 {
matrix A
matrix B
}
Mxgroup2 {
matrix C
matrix D
}

And I want to employ the constraint A + B = C + D

Any ideas how I can do this?

Posted on
No user picture. kaje Joined: 06/05/2019

factor scores curiosity -- comparing OpenMx and lavaan

Hi,
when estimating a very simple latent variable autoregressive panel (AR(1)) model with an integrated trend component, I noticed that the factor scores based on the regression method do not include the trend (or maybe they are a kind of detrended). I'm wondering whether there maybe is a reason or a rationale behind this that I don't see. If you add the model implied means to the factor scores, you get the same factor scores as when using lavaan.

Here is a minimal working example:

Posted on
No user picture. Veronica_echo Joined: 02/23/2018

OpenMx does not work after updating R 3.6

Hi everyone,

After updating R3.6, OpenMx doesn't work. My OS is macOS Mojave version10.14.5. I am pasting the error message I got. Any advice about it? Thanks in advance.

Veronica

Posted on
No user picture. Veronica_echo Joined: 02/23/2018

Error message of mxTryhard() with NPSOL optimizer

Hi everyone,

I installed OpenMx2.11 thought source('https://openmx.ssri.psu.edu/software/getOpenMx.R') and wanted to switch optimizer by mxOption(NULL,"Default optimizer","NPSOL"), but I got error message
Error in runHelper(model, frontendStart, intervals, silent, suppressWarnings, :
NPSOL is not available in this build. See ?omxGetNPSOL() to download this optimizer

I also had the same error message when I tried to use cluster to run the model.

How can I fix it? Any advice would be appreciated!

Posted on
No user picture. Veronica_echo Joined: 02/23/2018

Error message when using get() to return values of OpenMx object

Hi everyone,

I am trying to return values of an OpenMx object from optimized mxModel by get() (more details could be found in attached). Is there any other way to return the value of an OpenMx object by string? Thanks in advance.

Posted on
No user picture. Veronica_echo Joined: 02/23/2018

Remove path from an existed model

Hi all,
I would like to remove one factor, say "IQ2", from a CFA (script is below). Does it work if I rewrite the model as

cfa2 <- mxModel(cfa, "one factor", mxPath(from = "Q2", to = "Q2", arrows=2, values = 0, free = F),
mxPath(from = "Q1", to = "Q2", arrows=2, values = 0, free = F),
mxPath(from = "Q1", to = observed, free = F, values = 0)
)

Is there any more convinience way to remove path?

Thanks in advance!

Posted on
No user picture. Veronica_echo Joined: 02/23/2018

bootstrap coverage probability and the bootstrap replication

Hi everyone,

I am conducting a simulation study of a growth model and would like to evaluate the bootstrap CP of it. I kept the simulation replication as 1000 and set bootstrap replication as 1000 and 2000, respectively. The results seemed wiered, since the CPs of bootstrap 1000 (all of them were located between (0.93, 0.97)) were much better than those of bootstrap 2000 (some CPs were quite low, say 0.86). Any advice about this issue? Should I increase the bootstrap replication to a larger number, say 5000? Thank you in advance.