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st: Dummy Variable Trap


From   "Cordula Stolberg" <c.stolberg@gmx.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Dummy Variable Trap
Date   Tue, 7 Jun 2005 15:25:47 +0200 (MEST)

Hello All,

I have a panel regression, which I first run as a random effects regression
and then as pooled OLS. I have yearly observations and add a time dummy for
each year (the time dummies are also used for an interaction term with
another independent variable). I know that to avoid the dummy variable trap,
I should drop one of the dummies. I also know that Stata otherwise drops one
of the time dummies. Now I have estimated the random effects regression and
the pooled OLS regression and kept (by mistake) all of the time dummies.
However, instead of dropping one of the dummies, Stata kept all and
delivered results. What am I missing here?

Thanks,
Cordula
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