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RE: st: --estimates table, drop()" and FACTOR variables (texdoc)

From   "Clyde Schechter" <>
Subject   RE: st: --estimates table, drop()" and FACTOR variables (texdoc)
Date   Tue, 2 Aug 2011 21:38:18 -0700

"I run a few specifications then try to drop a factor variable (~300
dummies) but
--estimates table-- throws an error.&nbsp; Am I doing something
wrong?&nbsp; If
there is an issue with factor variables, is there a known workaround?"

This problem arises with several commands that require you to specify the
individual factor levels you want.  One solution is to build a macro that
contains what you need and then use that.  Start with -levelsof- and then
replace all the spaces by .varname.  Since the macro produced by
-levelsof- doesn't end with a space, you also need to stick .varname on
the very end.  Something like:

levelsof hsacode if e(sample), local(hsacodes)
local hsacodes: subinstr local hsacodes " " ".hsacode ", all
local hsacodes `hsacodes'.hsacode
estimates table, drop(`hsacodes')

Note that the if e(sample) clause is necessary so that the macro
`hsacodes' will only have terms that actually appear in the model.  You
might also have to fiddle with this a little more to eliminate the base
category for i.hsacodes--I don't know if -estimates table, drop()- will
choke on that or not.  [I use this technique mainly with the -test-
command, and -test- is quite tolerant of the base level.  -estimates
table- may or may not be.]

The second and third lines can also be replaced by a single call to the
-postlist- command in Nick Cox's -listutil- package if you have that

Hope this helps.

Clyde Schechter
Department of Family & Social Medicine
Albert Einstein College of Medicine
Bronx, NY, USA

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