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Re: st: why does stata creates missing values when running zinb model


From   Ekaterina Hertog <ekaterina.hertog@sociology.ox.ac.uk>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: why does stata creates missing values when running zinb model
Date   Wed, 19 Oct 2011 09:44:45 +0100

Dear All,

I am trying to run a zero inflated negative binominal model in Stata 11. My dataset contains 13440 women below 39 who are marriage agency customers. The customers of the agency HAVE to provide information on all the major demographic variables so there are no missing values on key variables (age, height, income, education etc). My dependent variable is nbidder which stands for the number of offers a given customer received over the past year. About 25% of women did not receive any offers (nbidder=0)

The command I typed is:

zinb nbidder prsexrat20441539 ciunmsexrat2039 guntotot age agesq bmi divwid havechildren lninc university smoker if age<=39 & sex==2, nolog inf(age agesq bmi havechildren lninc university) exposure(duration)

prsexrat20441539 ciunmsexrat2039 are measures of local sex ratio for each customer and guntotot measure how rural the area is.

Once I run the command I get a message (31478 missing values generated). I will be very grateful for any advice of why this may be happening,
Ekaterina

On 19/10/2011 00:28, Nick Cox wrote:
You fail to tell us anything whatsoever about your data (except that
the number of observations presumably is at least 3000) and you do not
tell us even the exact command you typed. This is quite contrary to
all the advice given to you in the FAQ and in particular repeated on
the list within the last 24 hours.

-set trace on- will show you where what you think is a problem occurs.
If the resulting log is long you may need to edit it for Statalist.
Otherwise why not liaise with Stata technical support directly? As
above, they will want to know about your dataset.

Nick

On Tue, Oct 18, 2011 at 11:20 PM, Ekaterina Hertog
<ekaterina.hertog@sociology.ox.ac.uk>  wrote:
Dear All,
I am trying to run a zero inflated negative binominal zinb model in Stata 11
and the first output Stata gives me is: 3000 missing values generated. I am
not sure why this is happening and it sounds wrong, but I cannot find out
what exactly this means and hence how to solve the underlying problem. Any
advice will be greatly appreciated,
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