Behavioral Genetics Models

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No user picture. Mirch Joined: 10/26/2018

Adding covariates to Cholesky script

Hi there, I am a new PhD student working on a project with twins for the first time. I've been provided with some older scripts from past students and some example code from a twin analysis workshop in Queensland that I haven't been able to attend yet (which I believe was run by Sarah Medland).

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No user picture. George Richardson Joined: 10/18/2018

Sex Limitation Model Question

Hi,
I attended the Boulder workshop a couple years ago and am now trying my hand at sex limitation modeling. Currently, I am working on a same-sex twin pair sex limitation model for liability to alcohol use disorder. I've found measurement invariance and A and C are invariant. C was non-sig. and is constrained to zero. The AUD factor intercept is invariant. Can I interpret the sex difference in the AUD means in terms of greater genetic risk for AUD in the males?

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No user picture. Aurina Joined: 01/05/2016

ACE including non-twin siblings

Dear all,

I'm trying to adapt ACE heritability model to include both twins and their non-twin siblings. The data used for the analysis are imaging-derived phenotypes from the human connectome project (HCP) which includes both MZ and DZ twin pairs as well as their non-twin siblings for a subset of twins. Would be really helpful if anyone could answer a few questions.

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No user picture. sealx017 Joined: 08/17/2018

Multivariate cholesky model

Hi,

I have a dataset of twins on 4 time-points. I can fit the Multivariate cholesky decompositon model with ACE components. It considers unstrcutured covariance matrices for A, C and E component. I was wondering if its possible to restrict it to a special structure? Like, say compound symmetric or AR1.

Thanks

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No user picture. Cuttlefish Joined: 09/12/2018

Different age (covariate) for siblings

Dear all,
I’m working on the bivariate ACE model from 2016 Boulder workshop from Hermione Maes ‘twoSATja’ and ‘twoACEja’ (http://ibg.colorado.edu/cdrom2016/maes/UnivariateAnalysis/scriptsOpenMx.shtml). I use questionnaire data and some participants filled this out one or two years later than their twin siblings, this means that some siblings differ in age. How do I adjust the model to allow different ages between twins? I keep running into problems with non-conforming arrays…

Below the parts of the script that I have trouble adapting:

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No user picture. massimiliano.orri Joined: 06/11/2018

Latent Growth Model and distal outcome

Hi,
I would like to fit the twin model in the enclosed figure, but I am not sure if this is feasible.
Can someone help me understanding if the model is identified?
In case, are there any exemples of R code for this model?
Thanks a lot
M
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No user picture. sealx017 Joined: 08/17/2018

Include covariates in multivariate cholesky model

Hi,

I have a dataset of twins on 4 time-points and a covariate which does not vary over time. I can fit the Multivariate cholesky decompositon model with ACE components but stuck at the case where I want to include that covariate at each time-point.

This how I was including the covariate (snp),

defSNP <- mxMatrix( type="Full", nrow=1, ncol=2, free=FALSE, labels=c("data.snp1","data.snp2"), name="snp" ) {note that snp1 corresponds to twin 1 and snp2 corresponds to twin 2)

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No user picture. szellers Joined: 04/04/2018

Constraining results of an algebra

Hi!

I am trying to constrain the results of an algebra, either to a fixed value or constraining the results of two algebras to be equivalent. I am using https://openmx.ssri.psu.edu//wiki/mxConstraint-help as a starting point.

Example output is attached, but the relevant lines of code are below

I want to fix AlCO[2,2] to 0 in the first example.

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No user picture. JuanJMV Joined: 07/20/2016

Moderation doubt

Hi everyone,
I am trying to test if there is a difference in one variable (quantitative) due to another variable (binary but different for each twin).
These variables are related and I want to test if there are different “subtypes” of that disorder (quantitative variable) depending on the value of the other variable (binary variable).
I was thinking to do a moderation analysis (as Rob suggested me in a previous post) as follows:
1-Quantitate variable
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No user picture. IvanVoronin Joined: 08/18/2013

Equality constraints in saturated model

What is the better way to introduce the constrains given that the constrained elements are computed, not defined as matrices?