Categorical Outcomes
Tom Rosenstrom
Joined: 03/01/2018
Pairwise maximum likelihood estimator available?
This is probably a good place to ask if anyone has implemented the new pairwise maximum likelihood estimator for Open Mx? For example, this paper mentions that "PLM fit estimates can also be obtained with Open Mx":
https://doi.org/10.3389/fpsyg.2016.00528
Julia
Joined: 03/29/2012
Estimating concordance
As far as I understand, it is possible to estimate concordance of a dichotomous trait through a liability threshold model. If so, could anyone guide me a bit how to do that? I'm totally lost and don't know how to incorporate that into a saturated model.
I'm interested in pairwise and casewise concordance.
Best,
Julia
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falkcarl
Joined: 10/29/2015
lower bounds on slopes of dichotomous and graded item response models
Rolandgem
Joined: 10/24/2015
Univariate Binary Model with multiple covariates that are binary, categorical, and continuous.
Error in runHelper(model, frontendStart, intervals, silent, suppressWarnings, :
MxComputeConfidenceInterval: reference fit is not finite
My guess is that it has something to do with the values or bounds?
What are some guidelines for choosing values when you have binary variables (as well as a mix of binary and continuous covariates)?
eivind
Joined: 11/04/2009
Categorical data with membership probabilities
I have ordinal data where the probability for membership in each category is known (e.g. individual i has probability p for being member of category 1 of variable u). Does anybody know if it is possible to utilize this information in OpenMx, for example by weighting the thresholds? The probabilities would be different across twins and across thresholds of the ordinal.
Natalja
Joined: 02/26/2014
Errors in script twinAceOrd.R
I am trying to learn how to fit a univariate ACE model when the variable of interest is ordinal. For this I've started with the script called Univariate Twin Ordinal-Matrix/twinAceOrd.R that I found under the TC 2012 - OpenMx website. When I run the code i get the following four error messages:
1st,
> # Generate Descriptive Statistics
> #colMeans(mzDataOrd,na.rm=TRUE)
> #colMeans(dzDataOrd,na.rm=TRUE)
> cov(mzDataOrd,use="complete")
Error: is.numeric(x) || is.logical(x) is not TRUE
> cov(dzDataOrd,use="complete")
Error: is.numeric(x) || is.logical(x) is not TRUE
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iloo
Joined: 05/26/2010
Definition variables for categorical and continuous variables, something's wrong
Something goes wrong when you include definition variables in a model where both continuous and categorical variables are included, and use the definition variables for regression on the mean. For example running this code yields on my machine:
library(OpenMx)
N <- 2000
u <- rbinom(N,1,.5)
x <- .5*u+rnorm(N)
y <- mxFactor( rbinom(N,1,pnorm(-2+u)) , levels=c(0,1) )
model <- mxModel( 'BinCont',
mxMatrix('Full',nrow=1,ncol=2,free=c(T,T),name='Betas'),
lingsuer87
Joined: 05/03/2013
ERROR for missing value where TRUE/FALSE needed
I am trying to add age as covariant into my liability threshold model. the script runs well before I add age covariant, However, after I add age covariate into the model, OpenMx always give me this error message:
Error in if (label %in% fixedVars && startVals[[label]] != value) { :
missing value where TRUE/FALSE needed.
Lisa
Joined: 06/07/2013
Proband ascertainment
I have a twin dataset with proband ascertainment (i.e. at least one proband in each pair is affected). I cant seem to figure out how in incorporate this in my ACE model - can anyone help? I have found several examples involving ACE models in twin data (for example http://openmx.psyc.virginia.edu/svn/tags/stable-1.2/demo/UnivariateTwinAnalysis_PathRaw.R) however none of these speak of how to take proband ascertainment into account.
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lingsuer87
Joined: 05/03/2013
If I have more than 3 levels for my ordinal variables then I have N-1 increments?
I am doing the threshold model for ordinal variables. and I finished the variables for 3 levels. However, I need modify the script to another variable which contain more 5 levels. I sucess with saturated model wiithout increments It gives me 18 parameters : rMZ,rDZ,4 threshold for MZ1 4 threshold for MZ2,4 threshold for DZ1 and 4 threshold for DZ2,respectively. But I was stuck at ADE model. Some problems in increments.
My script like this:
# Set Starting Values
thVals <-c(-0.226,-0.099,0.637,2.628) # start value for thresholds t1,t2,t3,t4.