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RE: st: Understanding Factor variables - is order significant ?


From   Richard Williams <richardwilliams.ndu@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   RE: st: Understanding Factor variables - is order significant ?
Date   Wed, 26 May 2010 01:58:50 -0500

At 12:41 AM 5/26/2010, Kieran McCaul wrote:
....

It's a bug, I believe.

In the example below there are two dichotomous variables, x1 and x2.
I declare the reference level for x1 to be x1=1 and leave x2 at its
default, x2=0.

If I fit x2#ib1.x1, all is well and x1=1/x2=0 is recognised as the
reference level.

If, on the other hand, I fit ib1.x1#x2, x1=1/x2=0 is recognised as the
reference level and dropped, but x1=0/x2=0 is also dropped.

Thanks Kieran. FYI, if you change the -poisson- commands to -regress- commands, everything seems to run correctly. So, if it is a bug (which to me seems extremely likely) it is a very quirky bug that affects some estimation commands but not others.


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Richard Williams, Notre Dame Dept of Sociology
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