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Re: st: GLLAMM


From   Stas Kolenikov <skolenik@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: GLLAMM
Date   Tue, 16 Feb 2010 13:09:49 -0600

One way to gllammify those zeroes in vitamin intake is to use
-family(poisson)- distribution with -link(log)-. May or may not help. If you
have sufficiently many observations with non-zero vitamin intake, run the
model on this subset only. If it converges, then the problem is indeed in
those transformations away from zero. If it does not, then you may have a
genuine underidentification.

On Tue, Feb 16, 2010 at 10:30 AM, arosella <arosella@irccsdebellis.it>wrote:

>  Dear Stata Listers,
> I'm trying to fit a GLLAMM to data from a case control study. I'd want to
> estimate the direct effect of some fixed-covariates (her only gender) as
> well as random effects of a latent variable (Protective diet) comprised of
> four observed variables (vitamins intake). Moreover  I'd want to estimate
> the indirect effect of the covariates via latent variable and an other
> random effect (non latent variable) on the thr outcome (see STATA code
> below). I get no error message from stata (that is I suppose that the syntax
> is right) but there are problems with the convergence (adaptative
> quadrature): some times stata says me that cannot calculate the LL and some
> times it take a lot of time until LL become flat. The problem may be of
> biological origin (no variability) but I don't believe that. Rarely a GLLAMM
> converges although I'm sure the code i right. Someone has encountered a
> similar problem fitting GLLAMM?
>

-- 
Stas Kolenikov, also found at http://stas.kolenikov.name
Small print: I use this email account for mailing lists only.
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