OpenSEM Forums
jarrode28
Joined: 03/01/2010
Correlated Genetic Factors in Independent Pathways Model
Hi,
I'm attempting to run a BG script of an independent pathways model on 9 dichotomous (symptom) manifest variables. That is, the model includes biometric factors specific to each manifest variable and common to all manifest variables. I've been able to get this model to run without any problems.
luna.clara
Joined: 12/23/2012
Theoretical question
Hi all,
I have a theoretical question.
In what ways apparent qualitative and quantitative sex differences are or are not addressed by simply adjusting for sex in a multivariate model?
The thing is that I observed in different univariate models that 3 of my 6 variables (for the multivariate model) had quantitative or qualitative sex differents... then I adjusted for sex and age in the multivariate model, but I'd like to explain in which way those genetic sex differences in some of the variables are addressed or not in the multivariate model just by adjusting for sex. Does it make sense?
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CharlesD
Joined: 04/30/2013
random variance parameters, or approximations of such?
Hi all. So I'm taking a look at a dataset of about 200 individuals, each with a number of variables measured 50 times longitudinally. A lot of these variables are scored on a scale of 0-100, which 'seems' to have created large differences in scale usage - differences that are no doubt normally there with a 0-10 scale but are probably emphasised now. If the measurement model were equivalent across individuals, then the structural model is clearly not anyway, so I have a similar issue, or probably both measurement and structural differences.
luna.clara
Joined: 12/23/2012
How to add a second latent common A factor in an independent pathway model
Dear all,
I have run without problems a multivariate IP model for 6 variables.
The thing is that now I would like to add another latent common A factor that loads only on 3 of the 6 variables to see if this "new" 2-IP factor model (two Ac factors) fits better the data than the 1-IP factor model (just one Ac factor for all the observed variables).
But I think I’m doing something wrong because the model doesn't understand that the second common A factor is loading only in the first 3 observed variables. Can anybody help me? Many many thanks!
YiTan
Joined: 10/08/2014
A question about moderator variable
Hi all,
I'm new to OpenMx and SEM, and I have just read through the various examples on twin modelling. Just wondering, if I have a moderator variable which varies within twin 1 and twin 2 and also across twin pairs, how do I go about specifying it as a definition variable? Or do I have to do bivariate analysis instead (treating the moderator variable as another variable?)
Thank you very much!
Cheers,
Yi
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RFrank
Joined: 06/08/2012
Cholesky decomposition between a binary and a continuous variable?
Is anyone aware of a script to do a Cholesky decomposition between a binary and a continuous variable?
I attempted to adapt a script I found here (http://www.genepi.qimr.edu.au/staff/sarahMe/workshop14/Day3.zip) and listed it below, but it's not running.
require(OpenMx)
require(psych)
source( "http://www.vipbg.vcu.edu/~vipbg/Tc24/GenEpiHelperFunctions.R")
nl <- read.delim("Cholesky.dat", header=T, sep="\t", na.strings=".")
nl$family1 <- nl$fam
nl$family2 <- nl$famb
nl$happy1 <- nl$max
nl$happy2 <- nl$maxb
# Select Variables for Analysis
fife
Joined: 07/01/2010
"Observed" correlation matrix with missing data--is it computed?
I've got a bit of an unusual question. I have missing data and I'm taking advantage of FIML's algorithms to handle that missingness. I know the EM algorithm will return a "corrected" correlation or covariance matrix. Will FIML do the same? I know it returns corrected model estimates, but I can't see how I'd extract the corrected correlation matrix. When I type:
model$data
It returns the raw dataset (with missing values still missing).
Any ideas?
fife
Joined: 07/01/2010
AIC/BIC is NA, but other FIs are computed
Hi all,
I've run a model and am a bit puzzled that it won't give me the information criteria (AIC and BIC). Everything else is computed, including chi, k, and df, which are the sufficient statistics. Am I missing something? I've included a screenshot. It seems the AIC should be
1557.625 + ncol(d)*(ncol(d)-1)-2*453 = 1707.625,
where ncol(d) = 33
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Pasquarella
Joined: 09/29/2014
Non-significant Slope Variance in LGC
Hello all,
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izza
Joined: 08/12/2014
equal means and variances in multivariate model
Hi there,
I want to test for equal means and variances across twins and zygosities in a trivariate model, separately for the measures.
In the trivariate script I am using, http://ibg.colorado.edu/cdrom2014/bartels/Multivariate/Trivariate.R , the means and variances are tested together and I am not sure how to separate them.
Can I use my results from univariate saturated sub models or is there a way to test for it in a trivariate model?
Many thanks!