----- Original Message -----
From: "0087209s" <[email protected]>
To: <[email protected]>
Sent: Tuesday, May 06, 2003 5:54 AM
Subject: st: truncation and endogenous stratification in TCM
> I am trying to estimate a travel cost model for whitewater recreation
using
> the usual negative binomial distribution. My sample is from an on-site
survey
> so I need to take into account the fact that my observations are truncated
at
> positive trip demand as people who have not visited the river are not
included
> and also the problem of endogenous stratification (the likelihood of being
> sampled depends on the frequency of visiting the site).
>
> my question is how I might take these 2 factors into account using the
nbreg
> function (negative binomial distribution)within Stata? Is there some
optional
> command that I can use along with nbreg?
>
> Thanks for the help,
>
> Stephen
>
Hilbe's -trnbin0- (0-truncated negative binomial regression) will deal with
the first problem. You can use -findit- to download the program.
Hope this helps,
Scott
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