OpenSEM Forums
lior abramson
Joined: 07/21/2017
script for ACE model with covariates using paths specification
Hello,
Does anyone know where can I find a reliable example of an openMX script to an ACE model with covariates (e.g., age) using path specifications? I saw that there is an example with matrices analysis, but since I only now begin to get my hold on openMX, I would like to understand the syntax of paths analyses before jumping to a new method...
Also,do you know on some kind of a workshop (somewhere in the world or online) that teaches openMX and twins analyses from the beginning?
Thanks!
lior abramson
Joined: 07/21/2017
Starting values in a univariate ACE model
Hi,
I am very new to twin analyses in general, and even newer to openMX.
I have tried to perform a simple univariate ACE model using paths specifications. I followed the example called "ACE model: A twin analysis" (section 2.5.1) in the openMX user guide.
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JuanJMV
Joined: 07/20/2016
Intra Class Corelations
Hi I am doing some univariate analyses but I have one doubt when about how getting the intraclass correlations for MZ and DZ. I have tried with cov2cor but I can not make that work. Here is the script:
# Select Variables for Analysis
vars <- "AG_Ln" # list of variables names
nv <- 1 # number of variables
ntv <- nv*2 # number of total variables
selVars <- paste(vars,c(rep(1,nv),rep(2,nv)),sep="")
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deManzano
Joined: 04/09/2015
variable with inherently skewed distribution
Hi everyone,
I would like to perform classical twin modeling on a variable with an inherently very skewed distribution (positive). I asked around a bit and the suggestion I got was to cut my original continuous data into bins, treat the variable as ordinal, and use a threshold liability model. However, this approach still assumes an underlying normal distribution. Would there be any way of generalizing the modelling in OpenMx (as e.g. in generalized linear regression)? Do you have any other suggestions or recommendations?
Cheers,
Örjan
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JBosdriesz
Joined: 03/07/2017
Bivariate twin model (output)
Hello,
I've done some univariate twin model analyses in OpenMx recently, but now I'm trying my hand at bivariate models.
I'm using a script by Hermine (http://ibg.colorado.edu/cdrom2016/maes/MultivariateAnalysis/mulACEc2.R).
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dacan
Joined: 06/04/2017
Selecting the best model for LGM Twin model
Hello everyone,
in my work, I am trying to capture longitudinal development of depression with a biometrical quadratic LGM model following model described in Reynolds, Finkel, McArdle, Gatz, Berg, & Pedersen (2005; see Figure 2). Here are the specifications:
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MichelNivard
Joined: 05/16/2017
Cholesky model WLS
Hi,
I am running Hermine's Cholesky script (Boulder "cdrom" 2016) only change I make is that I Use mxDataWLS to precompute the polychoric correlations and WLS weights:
DZdata <- mxDataWLS(DZ)
This runs without errors.
I then proceed to adjust the mxExpectation to reflect the nature of the data:
expMZ <- mxExpectationNormal( covariance="expCovMZ", means="meanG",thresholds="Tr", dimnames=selVars )
expDZ <- mxExpectationNormal( covariance="expCovDZ", means="meanG",thresholds="Tr", dimnames=selVars )
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JuanJMV
Joined: 07/20/2016
Trivariate Model
Hi Everyone,
I am trying to fit a trivariate model since I think is the best option instead two separately bivariate models but I am not sure.
I have two errors:
1)
Warning messages:
* thinG <- mxMatrix( type="Full", nrow=nth, ncol=ntvo, free=TRUE, values=svTh, lbound=lbTh, labels=labTh, name="thinG" )
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xixizhao
Joined: 04/11/2017
How to get the P value of heritability in ACE model
Hello all,
I am very new with ACE twin modeling as well as R, therefore I need some help.
jjmorosoli
Joined: 04/15/2015
Moderation of OSDZ intrapair correlation (ra, rc) in a sex-lim model
Hello everyone,
I want to study if the similarity (through A and C) between female twin and male twin, within pair, changes due to a moderator (as age) using the GxE approach of Purcell (2002) in a sex-limitation model.
I thought to put it in a very simple way such as:
rados <- mxMatrix(type="Full", nrow=1, ncol=1, free=F, values=0.5, label="rg", lbound=-1, ubound=1, name="ra")
rcdos <- mxMatrix(type="Full", nrow=1, ncol=1, free=T, values=.01, label="re", lbound=-1, ubound=1, name="rc")