st: RE: Unordered Categorical Predictor Variable

["Lachenbruch, Peter" <Peter.Lachenbruch@oregonstate.edu>]

i may be missing the point here, but why cant you use the factor variable coding (i.varname)  you can vary the base variable.  See factor variable in manual.  comparing all possible factor codings doesn't make much sense since they will be dependent, and you can use contrasts for whatever you want.

Peter A. Lachenbruch,
Professor (retired)
________________________________________
From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] on behalf of louis grandjean [lgrandjean@gmail.com]
Sent: Thursday, January 24, 2013 7:08 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: Unordered Categorical Predictor Variable

Dear Statalist,

I'm using Stata 11 and am struggling with how to best analyse an
unordered categorical predictor in a logistic regression.

My categorical predictor is "bacterial family" so it doesn't make
sense to always compare one family to an arbitrarily chosen reference
family.  What I want to do is compare each family in turn to all the
other families.

I think deviation coding would give me one family vs the mean of all
the families, but I want to get one family vs the other famlies, and
obtain an odds ratio for each level.

I've looked at xi3 but this doesn't seem to answer the problem.

I'd be very grateful for your thoughts.

Best wishes Louis
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