Behavioral Genetics Models
inooradd
Joined: 03/11/2020
Step 1: Testing basic assumptions (equal means & variances for twin 1/twin 2 and MZ/DZ pairs)
Hello!
I am following the steps laid out in [this](https://vipbg.vcu.edu/media/course/HGEN619_2015/TwinModels.pdf ) openmx presentation and could use help with step 1.
1. Use data to test basic assumptions (equal means & variances for twin 1/twin 2 and MZ/DZ pairs)
valentinav
Joined: 06/15/2020
ACE model lower CI negative number
Hi All,
I am new to ACE model estimation so I am trying to follow some tutorials I found online (script attached).
The results seems fine, and are also coherent with another script I used. However, I got negative lower CI: ACEvc.VarC[1,4] -0.2443061 0.23255753 0.7557620.
Does this make sense to you? As far as I know when CI include 0 we cannot conclude that the value is different from 0...
I would really appreciate whether someone could help me with this.
Thank you in advance!
Best,
Valentina
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inooradd
Joined: 03/11/2020
Comparing ACE and ADE models
Hello,
I have a couple of questions regarding comparing ACE and ADE models.
1. Is there a quick method of comparing the fit of both of these models? As of right now I am running the scripts for each model, then comparing the two models using mxcompare:
<%
mxCompare( fitADENOTW , fitACENOTW ) %>
I know typically when we compare nested, we run something to the effect of...
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Benny
Joined: 05/15/2020
GxE with latent moderator
Hello,
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Leo
Joined: 01/09/2020
Bivariate Cholesky model with one continuous and ordinal variable
I'm new to OpenMx and I'm trying to understand the Boulder workshop scripts.
Particularly, I am trying to fit a model with one continuous and one ordinal variable. I have found this script but it is modeling only two ordinal variables:
http://ibg.colorado.edu/cdrom2016/maes/UnivariateAnalysis/twoa/twoACEoa.R
Is there a shortcut to only apply the threshold to one variable?
Thanks in advance.
JuanJMV
Joined: 07/20/2016
Interpret >1 and negative results from variance parametrisation of twin model
Hi All,
I am using the new parametrization for a bivariate model, as suggested in "Type I Error Rates and Parameter Bias in Multivariate Behavioral Genetic Models".
The results (see below) include an rA correlation that is higher than one.
Am I doing something wrong or I have to interpret the rA correlation as 1?
The phenotypic correlation is .2. Is it be correct to say that is due to 1, -.96 and .2 for A, D and E respectively?
There are also negative values: there is no way to interpret these results, right?
twolf
Joined: 04/24/2020
Should I ever need lower bounds in a twin model?
Hello,
I am currently starting to familiarize myself with different variations of the ACE-model as well as nuclear twin family designs in OpenMx and although coming from econometrics I dreaded working with SEMs so far I find the ride quite exhilarating.
While trying to reproduce certain results from the literature to broaden my understanding I sometimes encounter a strange behavior where I obtain a parameter estimate which is quite close to what I would expect with the only issue being that it is actually negative.
lior abramson
Joined: 07/21/2017
negative path estimate in UMX cholesky
Dear forum,
I conducted a Cholesky model with two variables in two time-points, using the uxACE command, and then conducted a model fitting procedure with the umxModify command. The model was an ADE model.
The results I got (a screenshot is attached) make perfect sense in terms of the overall explained variance by genetics. Meaning, if I compute the variance explained by both A and D for each variable (after squaring each path), I get the same amount of explained genetic variance as in the univariate models for each variable.
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benruk
Joined: 12/09/2019
Covariate Effect in Liability Threshold Model
Hello,
I want to write a script for a GxE-interaction with an ordinal outcome and a continuous moderator and was looking for some scripts that include a covariate effect on an ordinal outcome variable.
In this search I found a [script](https://static1.squarespace.com/static/58b2481a9f7456906a3b9600/t/5d9c0be7b3de004d53e6456b/1570507752071/oneACEoa.pdf) by Hermine Maes where she models the effect of the covariate (age) on the mean of the liability distribution of the outcome variable.
MIRELA
Joined: 04/03/2020
Biometrical model fitting
My question concerns choosing the best fitting model. Given the twin correlations in a given phenotype (rMZ = 0.50, rDZ = 0.34), it seems that the model to be tested should be the ACEmodel (because rMZ < 2rDZ).
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