OpenSEM Forums
JuanJMV
Joined: 07/20/2016
Bivariate model — non-linear association
Hi All,
I am working on a bivariate model for two continuous variables (normally distributed).
I have checked the association between these variables and looking at the plots the relationship seems to be non-linear. I have run a regression model and the association is significant but it is probably better explained by a quadratic or U-shaped association.
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Ilaria
Joined: 07/22/2024
Multivariate code ACE models (path and variance based models)
Hi all!
I have two questions regarding the script I am using to fit a multivariate model exploring the association between body dissatisfaction (exposure X1) and depressive symptoms at ages 21 and 26 (outcomes Y1 and Y2) whilst accounting for twins' sex and age (residuals being regressed).
I have tried to adapt Hermine's code but I am not sure this is correct. I do get estimates and correlations for all the parameters (X1, Y1, Y2).
However, I am not sure about the following:
Zhiyang
Joined: 12/11/2024
Very small estimate with a very large standard error in univariate modelling.
Dear all,
This is the first time to have a post in this forum, and thanks for the platform.
I am a researcher working on the Finnish Twin Cohorts, and I am doing a univariate twin modeling on depression. I have 113 DZ pairs and 69 MZ pairs. The outcome of depression is basically normal-distributed.
Then in the ADE model, I get the data summary and results like this:
Stefano5
Joined: 06/30/2023
ulancia
Joined: 10/10/2024
Longitudinal twin analysis with at most three time points
Hello, I'm working on a twin database (monozigotic and dyzigotic) with 537 twin pairs, of which 311 are present in only one wave, 139 have two time points and 77 three data points.
I fitted the saturated and ACE models on the 311 with one time point only, but I'm wondering how to use the longitudinal aspect in the 216 twin pairs, as I did with linear mixed models in which I added random components.
Can you suggest a way (and/or also a possibile script) for this analysis?
Many thanks in advance
Ugo Lancia
caitlin2727
Joined: 06/04/2024
two-level growth mixture model
I am trying to fit a two-level growth mixture model (which is three-level LMM with two latent classes).
The subject's outcome (y0, y1, y2, y3) is nested within the subject and then nested within different centers.
##wide type
data <- reshape(indata[,c("Center","ID","Time","y")], idvar = c("Center","ID"), timevar = "Time", direction = "wide", sep = "")
centerdata= data.frame(Center= mydata3[!duplicated(mydata3$Center),1])
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JuanJMV
Joined: 07/20/2016
How to add object to a model without re-run
I have fitted a very computationally demanding model (around one week) and now I need to add an mxAlgebra object into this model:
threG2 <- mxAlgebra( expression= threG[,1:7], name="threG2" )
I know I can do it in this way:
modelIPAE2 <- mxModel( fitIPAE,threG2, name="mulIPAE2c" )
fitIPAE2 <- mxTryHardOrdinal( modelIPAE2, intervals=F, extraTries=11 )
But I wonder if there is any way to modify the model without re-running it
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tvo015
Joined: 01/18/2024
Van der Sluis in OpenMX?
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JuanJMV
Joined: 07/20/2016
Fix mean latent variable
I am working on a CP model (using a reference script from Boulder). I would like to know if it is possible to fix (or freely estimate) the mean of the latent variables (here the latent factor) using a model specification like this one (see below). Would it be possible by fixing one of the manifest means? I know it is possible (and must be done) to fix the variance to one so that the model is identified but I am also curious if the mean of latent variables can be fixed (or freely estimated). If so how could I do it?
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tvo015
Joined: 01/18/2024