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Behavioral Genetics Models

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No user picture. qingwen Joined: 08/15/2019

nuclear twin family design in OpenMx

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Behavioral Genetics Models
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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No user picture. Aurina Joined: 01/05/2016

Assumptions bivariate ACE twin model

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Behavioral Genetics Models
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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No user picture. JuanJMV Joined: 07/20/2016

Saturated vs ACE model- different correlations

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Behavioral Genetics Models
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.

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No user picture. diana Joined: 04/17/2019

what are the meanings of definition variables in SEM in twin studies

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Behavioral Genetics Models
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.

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No user picture. thughe01 Joined: 10/18/2009

ACE model with technical replicates

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Behavioral Genetics Models
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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No user picture. noamm Joined: 10/10/2018

Failure to obtain CI's for a umx model

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Behavioral Genetics Models
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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Picture of user. chancey Joined: 09/09/2017

Modeling Suggestions for Experimental Data

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Behavioral Genetics Models
Question for the group: How might one go about modeling experimental data with twin respondents?

I ran a single-factor survey experiment with a small group of twin respondents (MZs and DZs, mainly same sex). There were two conditions. I randomly assigned twins to receive either:

Conditions A A
Conditions B B
Or
Conditions A B (or B A)

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No user picture. JBosdriesz Joined: 03/07/2017

Age as covariate or moderator

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Behavioral Genetics Models
I looked around the forum, and found referrals to a post that might address this issue, but that page wouldn't load anymore, so I thought I'll post my question here.

I'm running a set of univariate ACE models, on a range of outcomes. I have two age groups (3-4 and 7-8), that I would like to analyse separately, by also combined.

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No user picture. camus Joined: 03/21/2019

Obtain 95%CI for ACE model- script revised from Dorothy Bishop

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Behavioral Genetics Models
Hi, I am new with R and OpenMx. Recently I revised Dorothy Bishop's script to run ACE models. However, her original code could not get the 95%CI for of A,C,E estimates, but only 95%CI for Unsquared path estimates. I know mxCI() can obtain 95%CI, but after various attempts, it never works for me. Could any expert have a look of the code and let me know how should I add it?
Thanks!
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No user picture. diana Joined: 04/17/2019

I am wondering if define variables will decrease E and increase A?

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Behavioral Genetics Models
I am wondering if too many define variables will decrease E and increase A?

For instance, I want to estimate the heritability of coronary heart disease (CHD), should I adjust all the risk factors of CHD as much as possible, such as smoking, drinking and BMI? I'm afraid that it will overestimate A and underestimate E since I saw a revelent [paper](https://www.ncbi.nlm.nih.gov/pubmed/15520515/).

Many thanks!

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