Multilevel mixture IRT simulation PreviousNext
Mplus Discussion > Latent Variable Mixture Modeling >
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 şeyma posted on Tuesday, March 11, 2014 - 8:57 am
Dear Mplus users,

1. I am trying to running example 10.5 monte carlo study. But I want this data include a covariate variable. (for example a gender variable: 600 females in latent class 1, 400 males in latent class 2; 400 females in latent class 2 and 600 males in latent class 1=2000 observations totaly gender splşt is 50% and . How can I add such a variable in this study?

2. Another question is: Which prior paramter used for this simulation study? Can we generate response patterns in this example based on item response model? Because I want to item diffuculties differ between latent classes.

Thank you.

Şeyma
 Bengt O. Muthen posted on Tuesday, March 11, 2014 - 12:10 pm
First, note that this is an advanced analysis that calls for experience with Mplus Monte Carlo simulations.

1. You add a binary x variable (see UG chapter 11 for how to do that) which influences the latent class variable ("c ON x").

2. You can use parameter values from a real-data analysis.
 şeyma posted on Tuesday, April 08, 2014 - 4:34 am
Dear Bengt Muthen,

I try to fit my data to the multilevel mixture item response model. For this reason I used example 10.5. I guess the syntax is for 1-PL model or Rasch model. I have now class spesicific item diffuculties.

I want to use these parameter for differential item functioning detection. But I wonder that these item diffuculties directly comparable? Should I bring the parameters the same scale?

Thanks,

Şeyma
 Bengt O. Muthen posted on Tuesday, April 08, 2014 - 8:29 am
Ex 10.5 uses a 2PL model.

To have a comparable latent variable scale you need to start with equality of loadings and thresholds across the classes. Then you can free up some of those equalities to capture DIF.
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