Mixture model with Count data: mean g... PreviousNext
Mplus Discussion > Latent Variable Mixture Modeling >
Message/Author
 Loes Keijsers posted on Thursday, October 11, 2007 - 5:46 pm
Dear Dr. Muthen,

I ran a longitudinal mixture model (c=5) over several measurement waves of count data. The output of this analysis does not give the mean growth factors for each latent class as shown in the graph (plot 2).

How can I obtain the mean intercept and slope factors for each latent class, as well as their significance level?

Thank you for your help.

Loes Keijsers
 Linda K. Muthen posted on Thursday, October 11, 2007 - 9:21 pm
The growth factor means for each class should be in the results. If you can't find them, please send your input, data, output, and license number to support@statmodel.com.
 Loes Keijsers posted on Friday, October 12, 2007 - 3:51 pm
I found the growth factor means, but these are the log-transformed values (as I use count-data). For instance the intercepts are negative, whereas the scale ranges from 0 to 4. Is there a means of obtaining the "real" values that match the graphs?
 Linda K. Muthen posted on Friday, October 12, 2007 - 9:21 pm
I think you will find what you want if you ask for RESIDUAL in the OUTPUT command. These are the values that are plotted.
 socrates posted on Thursday, February 26, 2009 - 9:39 am
Hi

When running a GMM with two parallel processes (one continuous and one count variable) and adding a variable to predict growth parameter variances of the continuous variable, I always get the following error message:

THE MODEL ESTIMATION DID NOT TERMINATE NORMALLY DUE TO AN ILL-CONDITIONED
FISHER INFORMATION MATRIX. CHANGE YOUR MODEL AND/OR STARTING VALUES.

THE MODEL ESTIMATION DID NOT TERMINATE NORMALLY DUE TO A NON-POSITIVE
DEFINITE FISHER INFORMATION MATRIX. THIS MAY BE DUE TO THE STARTING VALUES
BUT MAY ALSO BE AN INDICATION OF MODEL NONIDENTIFICATION. THE CONDITION
NUMBER IS 0.442D-10.

THE STANDARD ERRORS OF THE MODEL PARAMETER ESTIMATES COULD NOT BE
COMPUTED. THIS IS OFTEN DUE TO THE STARTING VALUES BUT MAY ALSO BE
AN INDICATION OF MODEL NONIDENTIFICATION. CHANGE YOUR MODEL AND/OR
STARTING VALUES. PROBLEM INVOLVING PARAMETER 64.

Parameter 64 refers to the last measurement occasion of the continuous variable in THETA.

Do you have any idea why this happens and how to solve this problem?
 Linda K. Muthen posted on Thursday, February 26, 2009 - 3:46 pm
This message depends on the data and the model. Please send your input, data, output, and license number to support@statmodel.com.
Back to top
Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: