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Re: st: zero-inflated Tobit models


From   Nick Cox <njcoxstata@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: zero-inflated Tobit models
Date   Mon, 10 Jun 2013 11:28:01 +0100

I think you are downplaying very good advice from Austin here. If you
have any negative values, a tobit with censoring at zero sounds wrong
in principle. Trying to complicate an incorrect model does not seem
like a good strategy.

Nick
njcoxstata@gmail.com


On 10 June 2013 11:18, Katie Farrin <kfarrin@gmail.com> wrote:
> Thanks, Austin,
>
> I inquired about zero-inflated models because the regression I'm
> performing is a first-stage regression in an IV model.  I am
> instrumenting for business profits due to nonrandom selection into
> owning a business.  I merely wanted a better fit to improve the
> significance of my second-stage results (I'm bootstrapping my errors),
> and thus am not sure I need GMM or SEM at this point in my research.
> While the data isn't technically censored at zero, I have only 4 (out
> of 1900) observations where profits are to the left of zero.  I have a
> lot of zero observations (about 1500),
>
> Again, does anyone know of a zero-inflated Tobit command (or option
> within a command) in Stata?
>
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