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Re: st: Oaxaca and categorical variables


From   "Ben Jann" <ben.jann@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Oaxaca and categorical variables
Date   Tue, 25 Nov 2008 10:21:34 +0100

> For at each one of the dummy groups in your example oaxaca cannot find
> such a reference dummy variable.

"For at least one ..." I wanted to say.
ben


On Mon, Nov 24, 2008 at 9:36 PM, Ben Jann <ben.jann@gmail.com> wrote:
> A dummy variable for the reference category must exist in the data. So
> if, say, condnum has 9 categories, 1 through 9, you need nine dummies,
> one for each category. In the main model, you can only specify eight
> dummies (to prevent perfect collinearity), but if you use the
> categorical() option then the 9th dummy has to exists and you have to
> identify it.
>
> For at each one of the dummy groups in your example oaxaca cannot find
> such a reference dummy variable.
>
> ben
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