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Re: st: AW: double hurdle model with Tobit second stage estimation

From   David Jacobs <>
Subject   Re: st: AW: double hurdle model with Tobit second stage estimation
Date   Wed, 25 Feb 2009 13:46:57 -0500

You've probably thought of this as well, but what about the -zip- or -znb- models in Stata. Those options allow large proportions of zeros in your outcome variable.

Is the problem with these models that the values above zero are not integers? If they are integers or could be made into integers without messing things up, then these two equation count estimators might work.

Dave Jacobs

At 01:16 PM 2/25/2009, you wrote:
Heckprob is not appropriate in my case. Heckprob would treat the pile of zeros i have as unobserved whereas the Tobit treats them as observed zeros. This is the case in my data and therefore heckprob is not an appropriate model. I could run a first stage Probit then a second stage Tobit. However, the Tobit in the second stage does not use all the data observed and hence the standard errors will not be correct leading to wrong t statistics and be unable to interpret the results.


Martin Weiss wrote:
Have you looked into

help heckprob



-----Ursprüngliche Nachricht-----
[] Im Auftrag von Kirimi Sindi
Gesendet: Mittwoch, 25. Februar 2009 17:43
Betreff: st: double hurdle model with Tobit second stage estimation


I working on a double hurdle model. The first stage is a Probit model and the second stage is Tobit due to pile up of zeros. Is there a do program that can assist me in this procedure to get the correct standard errors accounting for the first stage estimation?

Thank you,


Imagination is more important than knowledge. For while knowledge defines all we currently know and understand, imagination points to all we might yet discover and create.

Kirimi Sindi
PhD Candidate
Department of Agricultural,
Food, and Resource Economics
Room 20 Cook Hall
Michigan State University
East Lansing,  MI  48824
Telephone: +1-517-353-5320
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