OpenSEM Forums
joh4nd
Joined: 06/14/2023
family link functions v. threshold model on polychoric
Does OpenMx estimate the ordered family using a link function like probit or logit? Or may I open a feature request on github?
I found one years old [Q&A](https://openmx.ssri.psu.edu/node/4678) in this forum here stating the the threshold model was akin to the probit. And this other [Q&A](https://openmx.ssri.psu.edu/thread/4074) mentions how to specify a probit model. So I am asking this question for a clearer answer.
Benny
Joined: 05/15/2020
NTFD without zygosity information
Hello,
is it possible to estimate a NTFD without zygosity information? I know from other twin models that they can be adapted to this type of data. Is it also the case for the NTFD? If so, how would one adapt the script in OpenMx?
Best,
Mirko
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Zeynep_N
Joined: 10/03/2019
Multivariate binary-continuous twin model
Hi,
I am currently working on a multivariate correlated factors twin model with combined binary and continuous traits. I have six variables in total, the first two being binary data and the remaining four being continuous. I have been struggling for a while now in extracting meaningful output, specifically for the aetiological correlations. I receive genetic correlations with corresponding confidence interval lower bounds that are higher than the estimate itself (even though status is ok and model has converged).
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Benny
Joined: 05/15/2020
Twin Model Identification Matrix Algebra
Hello,
I was reading the book by Neale and Maes (2004) and they have a nice part about how to check the identification of a univariate twin model using matrix algebra (p. 104).
It is possible to check the identification of the model by representing the expected (co-)variances as a system of equation in matrix algebra:
Ax=b
where x is the vector of parameters, b is the vector of observed statistics and A is the matrix containing the weights of elements in x.
In the univariate case (ACE model), x=(a^2,c^2,e^2).
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ssciarra
Joined: 01/08/2021
Structured latent growth curve with definition variables
I am trying to fit a structured latent growth curve model where the actual days of observation are inserted into the latent variable loadings using definition variables. Unfortunately, I run into the following error:
Error in value[rows[[i]], cols[[i]]] <- startValue :
incorrect number of subscripts on matrix
Pablo F Cáncer
Joined: 08/15/2021
State space specification of Random Intercept CLPM
Hi, I'm trying to specify a RI-CLPM (Hamaker et al., 2015; Mulder et al. 2021) as a state-space model, but I don't know how to specify the two random intercepts used to capture stable between-individual differences in change. I've tried different ways of including them but none of them worked. Could you please help me identify which matrices should I modify to include the effect of the random intercepts? I leave my code below. Thank you very much for your attention!
szellers
Joined: 04/04/2018
Causal Common Contingent Modeling Code Help
Hi all,
I'm working on a model of smoking quantity given initiation of regular smoking along the lines of Bares, Kendler, and Maes 2015 among others. I'm having a bit of trouble figuring out how to move from a more straightforward bivariate model to the CCC model by implementing the estimated path from initiation to quantity. For reference, this is designated b in Figure 1 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4631696/
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szellers
Joined: 04/04/2018
Interpretation of Threshold Matrix, Ordinal Data
Hello,
I'm working with binary/ordinal models after many years of only working with continuous data in OpenMx. I have working scripts for liability threshold ACE models for both a binary outcome, and an ordinal outcome with three levels. I've referenced some of the lectures from prior IBG workshops but want to make sure I am interpreting my threshold output properly.
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Hal
Joined: 09/10/2021
Troubleshooting Error Message - MxTryHard()
##Hi,
##I'm running the univariate ADE model using Hermine's script.
##When it comes to testing the assumptions of equal means and variances, I keep getting the following error message:
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Hal
Joined: 09/10/2021
Re-Randomize Twin Order
Is there a code to re-randomize twin order?
Thanks!
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