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Mplus Discussion > Growth Modeling of Longitudinal Data >
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 Daniel Rodriguez posted on Friday, February 06, 2009 - 3:52 pm
Hello, I ran an LGM with a ZIP smoking variable (number of cigarettes smoked in the past 30 days). The outcome gave me the following feedback,

WARNING: COUNT VARIABLE HAS LARGE VALUES.
IT MAY BE MORE APPROPRIATE TO TREAT SUCH VARIABLES AS CONTINUOUS.

Would it be more appropriate in such case to log transform the variable instead of using ZIP?
 Linda K. Muthen posted on Friday, February 06, 2009 - 10:05 pm
You may want to do a log transformation. You could also consider a two-part model. See Example 6.16 in the user's guide.
 Daniel Rodriguez posted on Monday, February 09, 2009 - 10:13 am
Hi Linda, I did use the two-part already. One problem though, I am doing a mediation analysis but this analysis strategy won't do the model indirect because it employs integration. Is there another way to assess the indirect effect using a two-part model?
 Linda K. Muthen posted on Monday, February 09, 2009 - 12:32 pm
You can define indirect effects using MODEL CONSTRAINT. This will give you a standard error for each indirect effect you define.
 Daniel Rodriguez posted on Monday, February 09, 2009 - 5:47 pm
Thank you.
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