Re: st: double hurdle model with Fractional logit second stage estimation

[Jeph Herrin <stata@spandrel.net>]

Federico is correct, as long as your continous variable is 0 (and not missing) when the binary variable is 0. If it the 
continous variable is missing when the binary variable is 0, you can create a new depvar that has the correct properties:

  gen newdepvar=cond(var1==0,0,var2)

and use this as the depvar.

hth,
Jeph



On 5/6/2013 10:40 AM, Federico Belotti wrote:
> Dear Beatrice,
>
> if my understanding of your problem is correct, you can solve your issue by directly specifying as depvar your
> continuous variable. -tpm- will automatically generate (for the first part regression) a dummy equal to 1 when the
> continuous variable is greater than 0. My suggestion is to normalize your continuous variable in order to get a
> depvar that is bounded between 0 and 1.
>
> HTH, Federico
>
>
> On May 6, 2013, at 4:08 PM, Beatrice Muriithi wrote:
>
> > Thank you Jeph, I have installed tpm and tried to execute the model. Unfortunately tpm requires that the dependent
> > variables for both parts are the same (error:"The dependent variable must be the same in both equations" r(110)).
> > In my case, the dependent variable are different, the first stage has a discrete variable (0,1) and the second part
> > has continuous variable but include 0 and 100 (proportion). I will appreciate any further insights. Regards
> > Beatrice
> >
> >
> > On Mon, 06 May 2013 09:10:31 -0400 Jeph Herrin <stata@spandrel.net> wrote:
> > > Look at ssc describe tpm hth, Jeph On 5/6/2013 7:29 AM, Beatrice Muriithi wrote:
> > > > Hey,
> > > >
> > > > I have case of sample selection for which i would wish to use double hurdle model. The dependent variable for
> > > > the first stage is a discrete variable therefore i can use Probit model. The dependent variable for the second
> > > > stage is fractional response variable (contains 0-100  - percent). Is it ok if i use GLM (applied mainly for
> > > > fractional response variable problem) in the second stage? and if yes, 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 Muriithi Universität Bonn
> > > >
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> >
> > Beatrice wambui Muriithi Junior Researcher, Centre for Development Research, ZEF; Universität Bonn
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