Order of latent classes, GMM PreviousNext
Mplus Discussion > Latent Variable Mixture Modeling >
 Aaron Fisher posted on Thursday, December 03, 2009 - 6:56 pm

I have a GMM with 4 latent classes. When I estimate the model using this syntax:

classes = c(4);
analysis: type = mixture;
starts = 25 2;
model: %overall%
i s | d2@0 d3@1.75 d4@3.75 d5@7.50;
c#1 on d1;
c#2 on d1;
c#3 on d1;

i s;
i s;
i s;

I discover that there are negative error variances for the slopes for classes 2 and 3. I would like to fix these to zero however, every time I try to do so the classes change order and I am fixing the variances for the wrong class. I have seen advice on this message board re: using starting values to get a particular order for the latent classes. Nevertheless, I have been unable to effectively manipulate the order of the classes.

Any help you can give will be greatly appreciated.
 Linda K. Muthen posted on Friday, December 04, 2009 - 6:27 am
I would try using growth factor means as starting values. If this does not help, please send the input, data, output, and your license number to support@statmodel.com.
 Aaron Fisher posted on Friday, December 04, 2009 - 11:41 am
Thank you for your response.

I believe I have tried that. I specify those within the class-specific commands?

for example:
i s;

And this has not worked. If this is what you were suggesting, please let me know and I will send along the data, output, and lic #.

Thanks again.
 Linda K. Muthen posted on Friday, December 04, 2009 - 11:48 am
Yes, this is what I was suggesting.
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