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st: how to use ztnb?


From   Subramanian Swaminathan <ssubra@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: how to use ztnb?
Date   Sun, 17 Feb 2008 20:55:26 -0800 (PST)

Dear stata listers,

I am trying to fit a zero-truncated negative binomial
model to my count 
data. The data variables are mf-counts, age,
frequency. The model that I 
would like to fit is of the form:
xi:ztnb mf-counts i.age [fweight = freq] if
mf-counts>0, dispersion(mean)

Kindly note that my dispersion parameter is not a
constant but is a 
non-linear function as given below:

k = k0+beta*mean**gamma (0<gamma < infinity)

where,
'k' is the dispersion parameter 'k' ( in stata, k=log
(1/alpha) of the 
negative bonomial model

beta & gamma = coefficients to be estimated

In this model I want to test the hypothesis that
beta=0 against beta not 
equal to 0.

could anyone help me out, how the stata code should be
written to estimate 
the parameters of the model?

kindly note that i am new stata.

thanking you in advance and with kind regards
Subramanian Swaminathan
Vector Control Research Centre
(Indian Council of Medical Research)
Indira Nagar
Pondicherry - 605 006
INDIA 



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