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Re: st: tobit model in a percentage range


From   Tirthankar Chakravarty <tirthankar.chakravarty@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: tobit model in a percentage range
Date   Wed, 17 Aug 2011 00:12:20 -0700

Percentage and proportion data are modelled by so-called fractional
response regression models after Papke and Wooldridge (1996, Journal
of Applied Econometrics, Volume 11, Issue 6, pages 619–632). As you
correctly note, censored regression models do not make sense in this
context.

A comprehensive and recent survey is provided in Ramalho, Ramalho and
Murteira (2011, Journal of Economic Surveys, Volume 25, Issue 1, pages
19–68).

T


On Tue, Aug 16, 2011 at 11:57 AM, Cremades, Roger
<r.cremades@cranfield.ac.uk> wrote:
> Dear all,
>
> I am hesitating about using Tobit in a model with a dep var in a percentage range with values in 0 or 100, my dataset looks something like this:
>
> %ADOPTION (dep var)    subsidy    soil_clay    asset    ... more indep vars
> 0                                      1            1            200
> 100                                   0            1            590
> 0                                      0            0            700
> ...                                     ...           ...           ...
> 74                                    1            0            500
> 100                                   0            1            600
> 58                                    1            1            780
> 0                                      1            0            300
>
>
> OLS seems to produce bias in that case and I do not find information about how to justify using Tobit model in the stata book store or in Long/Freese book, most authors do it without justify it properly and I do not know if it is appropiate as there are no really censured values under 0 or above 100, may somebody help or give advice about appropriate background to justify pros/cons of using Tobit in this cases?
>
> best greetings and wishes,
>
> Roger
> ENREM MSc.
> Cranfield University
>
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>



-- 
Tirthankar Chakravarty
tchakravarty@ucsd.edu
tirthankar.chakravarty@gmail.com

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