OpenSEM Forums

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Picture of user. Rolandgem Joined: 10/24/2015

Analyzing heritability results of a covariate after running the ACE Model

I am studying the heritability of a variable by utilizing the ACE model, and would like to ask the OpenMX community if i am analyzing my results correctly.

When i run the ACE model, followed by the AE and CE models, i get the following results for 2 different datasets:

COMPARE ALL MODELS: Print Comparative Fit Statistics
(Nested.fit <- rbind(
mxCompare(SatFit, AceFit),
mxCompare(AceFit, AEFit)[2,],
mxCompare(AceFit, CEFit)[2,]))

Dataset 1

Model A (95% CI) C (95% CI) E (95% CI) (-2LL) df AIC ∆-2LL ∆df p-value

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No user picture. YiTan Joined: 10/08/2014

SLSQP error msg in univariate Ordinal ACE with age and sex as covariates

Hi,

I ran the attached ordinal ACE script with age and sex as covariates, and I noticed that for some of my variables I would get the following error message:

"Error in runHelper(model, frontendStart, intervals, silent, suppressWarnings, :
SLSQP: Failed due to singular matrix E or C in LSQ subproblem or rank-deficient equality constraint subproblem or positive directional derivative in line search "

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Picture of user. dtofighi Joined: 10/12/2009

Profile Likelihood CI for mediated effect

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

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No user picture. ismail74 Joined: 03/04/2016
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No user picture. jkarch Joined: 03/15/2011

Likelihood Ratio Test Extended SEM with Definition Variables

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.

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No user picture. JuliaJoplin Joined: 10/12/2014

Bivariate Cholesky with Covariates - Best Practice?

I'm doing a bivariate Cholesky decomposition between two variables that were measured at two different time points. I know that it's normally best practice to adjust variables for age and sex effects, and I see many different threads on this board that have discussed how to add covariates to an ACE model. Two questions:

1. For my purposes, should I regress out sex and age at time point 1 for the first variable and then regress out sex and age at time point 2 for the second variable?

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No user picture. Daxide Joined: 02/15/2016

Bivariate Cholesky: error in do.call

Hi! I am a novice, trying to move from univariate to multivariate analysis. So I downloaded the script cholesky.R from Sarah Medland's webpage (https://www.genepi.qimr.edu.au/staff/sarahMe/Workshop13.html), along with the data file. I tried to adapt the script to my data but I ran into an error. So I ran the script as I downloaded it, on the supplied simulated data, without modifying it (see eattachment) and I still encounter the same error, at this point.

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No user picture. k.j.kan Joined: 01/29/2016

Multivariate heritability in an independent pathway model

Dear Guinea-pig lovers,

Heritability is defined on the basis of phenotypic variance. One may regard a so-called common pathway model as a model that contains one or more latent phenotypes that mediate certain genetic and environmental effects on observed variables that function as indicators of those latent phenotypes. As a result the common pathway model enables us to calculate the heritability of both the mediating latent phenotype as well as the observed phenotypes.

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Picture of user. jmatosv Joined: 04/25/2015

2-step SEM model respecification

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

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No user picture. falkcarl Joined: 10/29/2015

Scaled chi-square

Forums

Hi all,

Wondering if Satorra / Satorra-Bentler scaled chi-square is available in OpenMx or not? i.e., ML with robust corrections to the test statistics and standard errors in the case of non-normal data. Ideally, I'd like to see if the difference test for model comparisons is available. Only thing I found in the forums was this post from quite a while ago: http://openmx.psyc.virginia.edu/thread/530

Many thanks!
Carl