Re: st: RE: random effects with truncreg possible

[Anita <anita.metzger@vtxmail.ch>]

Thanks you Tony, it is a Two Part Model indeed, but I was always told to 
use truncreg for the second part (after Probit), and so there is no 
option for panel. If you use normal multiple regression, results may be 
biased I would say...
Could anyone help me if my argument is wrong?


Lachenbruch, Peter schrieb:

> This sounds very much like a two-part model:  your 0 values are clearly
> identified, so a logistic regression (or probit) can be used to predict
> 0 or non-zero, and a multiple regression model can be used for the
> non-zero responses.  See an issue of Statistical Methods in Medical
> Research from 2001 that has several articles on this.  They are also
> called Hurdle models in Econometrics.
>
> Tony
>
> Peter A. Lachenbruch
> Department of Public Health
> Oregon State University
> Corvallis, OR 97330
> Phone: 541-737-3832
> FAX: 541-737-4001
>
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Anita
> Sent: Friday, February 08, 2008 5:06 AM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: random effects with truncreg possible
>
> Dear Statalist Members
>
> Sorry for posting again, I learned that I didn't explain my problem 
> accurately. Sorry for any inconvenience caused.
> I am currently estimating a model based on Cragg ("Some statistical 
> models for Limited Dependent Variable with Application to the Demand of 
> Consumer Goods", 1971)
>
> My research topic is to compare the models used in the literature to 
> explain the allocation of bilateral ODA (official development 
> assistance, so money for development).
> So there exist countries who do not recieve ODA (value =0) and others 
> do. I do have data on both. So it is not a typical truncation problem.
> First there is a selection equation to decide if a country gets ODA, I 
> estimate this via a Probit Model. (y1=1 if they get ODA)
> on a second step I estimate for all positive outcomes of the Probit 
> Model a Regression to estimate how much money they get.
>
> As I am working with a panel (different developing countries over time) 
> I would like to do this with random effects. For Probit there exists a 
> xtprobit command, for truncreg (command for the regressionpart) I didn't
>
> find anything.
> Is there a possibility to do this?
> As I indicated above, I have to compare the models used in the 
> literature, so I have to do Cragg's Model preferably with random effects
>
> so I can compare with other models.
>
> As a second question: is there a better way to solve the problem as with
>
> truncreg? As I know, the studies used this, but it does not seem to fit 
> very well
>
> thanks a lot
> Anita
>
>
>
>
>
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