Establishing model-fit with count ind... PreviousNext
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 Paul Agius posted on Thursday, April 16, 2020 - 5:17 pm
I'm writing a grant proposal where in the mixture model (LCA) measured indicator data will be counts - link functions are likely to be poisson, negative binomial etc. I'm likely testing 2-5 classes with between 10-25 indicators (potentially more). Are there model-fit strategies for count data given chi-square and LR chi-square would to be likely problematic given the large degrees-of-freedom implied here. Are there strategies others have employed with similar data - e.g. some form of grouped, model-based, probabilities compared to observed?? If so, any guidance on how one might go about undertaking this in the Mplus framwework would be appreciated

Thanks in advance

Paul
 Bengt O. Muthen posted on Friday, April 17, 2020 - 6:24 am
I think a good way to choose between models is to use BIC. Mplus also provides fit information for univariate and bivariate cases using TECH10. Have a look at how we did it in a longitudinal counts context in Section 6.5.1 of this paper which on our website under Papers, Growth Mixture Modeling:

Muthén, B. & Asparouhov, T. (2009). Growth mixture modeling: Analysis with non-Gaussian random effects. In Fitzmaurice, G., Davidian, M., Verbeke, G. & Molenberghs, G. (eds.), Longitudinal Data Analysis, pp. 143-165. Boca Raton: Chapman & Hall/CRC Press.
download paper contact first author show abstract
 Paul Agius posted on Sunday, April 19, 2020 - 6:37 pm
Thank you for your prompt and helpful reply, Dr. Muthen.

After playing around with my pilot data, am I correct in saying the univariate and bivariate residual tests in Mplus are limited to models with count data with relatively small maximum counts (say 10 or less?)? I have indicators which are scored/measured with much higher values and variance?

Also, are LMR and BLRT tests of comparative fit as problematic as the general chi-square measure of fit for the data, in the context of count indicators with relatively large values?

Thanks again for your advice.

Cheers
Paul
 Bengt O. Muthen posted on Monday, April 20, 2020 - 11:26 am
Q1: Right

Q2: I wouldn't use those tests but instead BIC only.
 Paul Agius posted on Monday, April 20, 2020 - 7:29 pm
Thank you.
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