Date:         Fri, 10 Sep 2004 08:30:06 -0400
Reply-To:     Peter Flom <flom@NDRI.ORG>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Peter Flom <flom@NDRI.ORG>
Subject:      Fwd: Effects Coding in PROC GENMOD
Comments: cc: Chuck Cleland <chuck.cleland@ndri.org>
Content-Type: text/plain; charset=US-ASCII

A colleague of mine asked about this.  Any help appreciated

<<<
  I have a set of models I am fitting with PROC GENMOD.  Here is a
little example:

DATA confid;
INFILE 'c:\ndri\DoubleTroubleRecovery\data\Sept2004-gee.dat' DLM=',';
INPUT p1v1 time $ dtraff confid qact pwellb qrela;
RUN;

PROC GENMOD DATA=confid;
 CLASS p1v1 time;
  MODEL qact = time dtraff dtraff*time
    / DIST=NORMAL TYPE3;
  REPEATED SUBJECT=p1v1 /TYPE=EXCH CORRW within=time;
  RUN;

  By default, I believe the time variable is dummy coded with the last
level as the reference category.  I would like to have the time variable
effects coded (deviations from the mean for all but one category).  Does
anyone know how to specify that?
>>>

Thanks

Peter

Peter L. Flom, PhD
Assistant Director, Statistics and Data Analysis Core
Center for Drug Use and HIV Research
National Development and Research Institutes
71 W. 23rd St
www.peterflom.com
New York, NY 10010
(212) 845-4485 (voice)
(917) 438-0894 (fax)