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From |
Austin Nichols <austinnichols@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Modeling % data |

Date |
Wed, 22 Sep 2010 12:09:12 -0400 |

Maarten-- I don't see how data approaching the boundaries is a problem in -qreg-, as long as the fraction at the boundary itself is not too large (though that in itself is more an indictment of the outcome measure than a necessary problem for quantile regression). If 10% of the outcomes are at the lower boundary (zero) for low X and 10% of the outcomes are at the upper boundary (100) for high X, how is that a problem for estimating how the conditional median changes with X? On Wed, Sep 22, 2010 at 11:51 AM, Maarten buis <maartenbuis@yahoo.co.uk> wrote: > --- 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.) * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**RE: st: Modeling % data***From:*Marlis Gonzalez Fernandez <mgonzal5@jhmi.edu>

**RE: st: Modeling % data***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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