OpenSEM Forums
George Richardson
Joined: 10/18/2018
Multivariate ACE Vs. Multilevel Model
Hi All,
I'm trying to understand the relationship between multivariate ACE models (e.g., Cholesky model fit to two phenotypes) and multilevel behavior genetic models. Is there a formal comparison somewhere?
My sense is that multivariate ACE models conflate within and between pair variance. A and C could capture within and between effects while E captures the within pair effects. E will map right onto the within pair effect in the multilevel model (MLM). Is all this correct?
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qingwen
Joined: 08/15/2019
nuclear twin family design in OpenMx
Hi, all
I am trying to fix a Nuclear Twin Family model in OpenMx.
Genetic and environmental parameter estimates in my model are obtained from four pieces of information, the covariance between MZ twins, the covariance between DZ twins and the covariance between parents and the covariance between parents and children.
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Aurina
Joined: 01/05/2016
Assumptions bivariate ACE twin model
Hello,
I am planning to do bivariate ACE modelling using IQ and brain imaging derived measures and I would be very grateful if you could help me answer a few questions regarding the general assumptions for this type of modelling.
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JuanJMV
Joined: 07/20/2016
Saturated vs ACE model- different correlations
Hi all,
I am trying to fit a univariate model.
I fitted the saturated model first and I got correlations of 0.64 and 0.34 for MZ and DZ respectively.
However, when I fitted the ACE model, I got these results:
A=0.04
C=0.52
E=0.44
So, I decided to check the correlations from the ACE model and I got 0.56 and 0.54 for MZ and DZ respectively.
I know that correlations may change from the ACE to the saturated model. However, these differences are huge.
PaulTwin
Joined: 01/29/2017
Latent spline/piecewise regression model on cross sectional data
Hello,
For my research, I would like to estimate the association between two latent variables using a spline/piecewise regression model with a single knot. The model should estimate two separate linear regression lines and the knot location (see attached image).
The two latent variables are anxiety and negative affectivity and both are measured with 7 indicators on a 1-5 Likert Scale.
ZR
Joined: 07/26/2017
Cross-lagged model issues
Hello,
I have a cross-lagged model that I have run using the code below:
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wisnies5
Joined: 07/03/2019
Categorical predictors and outcomes
Hello,
I am trying to build a model that includes morbidity count (0,1,2,3) as both a predictor and an outcome in the same structural equation model.
We created a simulated data set and tested our model, but unfortunately, the results are funky. Morbidity as the count outcome (with poisson dist) works, but issues arise with morbidity count as a predictor. I am guessing it is treating it as a continuous variable, which is not correct. Does anyone know of any tips/ideas to ensure that the count data is treated as such when it is a predictor?
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diana
Joined: 04/17/2019
what are the meanings of definition variables in SEM in twin studies
In the structural equation model, the definition variables are usually added in the regression of thresholds, such as age and sex. But I don't thoroughly figure out the meanings of them.
For instance, I want to estimate the heritability of smoking( binary variable) and age is added to adjust the threshold.
thughe01
Joined: 10/18/2009
ACE model with technical replicates
I'm re-entering the world of SEM after a hiatus and slowly familiarising myself with OpenMx (previous Mx user). I've successfully implemented some simple uni- and bi-variate VC models for some of our latest twin data (microbiome phenotypes) using the umx packages.
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noamm
Joined: 10/10/2018
Failure to obtain CI's for a umx model
Hi all,
I have used umx for a bivariate sex-limitation model, using the umxSexLim function, which have been a great help. However, I've failed in trying to compute CI's for my estimates, or any other indication of significance. Attached below are all the options I've tried. I would appreciate any help in how to compute any indication of significance.
Thanks!
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