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Mplus Discussion > Categorical Data Modeling >
 Ali posted on Tuesday, April 08, 2014 - 8:17 am
According to the report "IRT in Mplus" (Nov 14th, 2013), Logit/Probit Link, ML/ULS Estimators can be used for IRT modeling. However, I tried to use ML and ULS for a binary data set, and these two estimators doesn't work. The ML and ULS estimation cannot be applied to binary data, is it correct?
Here is a sample of my syntax:
DATA: file is dat1.txt;
VARIABLE: names are x1-x22;
!categorical are x1-x22;
ANALYSIS: estimator=ml;
!estimator=uls; parameterization=theta logit;
Model: Y by x1-x22*;
RESULTS ARE results.dat;

Second question:
How can I save the IRT item discrimination and difficulty estimates and their SE to a txt file? The SAVEDATA function only saves the factor loadings and thresholds. Is there a way to save the IRT item parameters?
 Linda K. Muthen posted on Tuesday, April 08, 2014 - 10:01 am
Both ULSMV and ML are available with categorical outcomes. I'm not sure why you think they are not available.

The IRT item parameters cannot be saved.
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