RE: st: Modeling % data

[Maarten buis <maartenbuis@yahoo.co.uk>]

--- On Sep 22, 2010, at 8:03 AM, Marlis Gonzalez Fernandez wrote:
> My outcome variable is a % (% error in a language test).  We do have  
> many 0 and 100.  I need to be able to do a multiple regression to  
> adjust for known predictors of the variable vs. the predictors of  
> interest.
>
> It was suggested that I use qreg.  I've done so and it seems to  
> work. 

This all depends on how close your dependent variable gets to the boundaries of 0% and 100%. If the data stays well within the range of
20%-80% than I would have no problem using either -qreg- or just regular
-reg-. However, when you have observations that get close to these 
boundaries, you'll probably want to take them into account. For that 
there is a whole suite of commands available, which I discussed at the
last German Stata Users' Group meeting:
<http://ideas.repec.org/p/boc/dsug10/04.html>

(You'd have to look at your variable as an proportion rather than a 
percentage. But that is trivial, just divide by 100.)

Hope this helps,
Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------


      

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