[R] contrasts in aov

Christoph Buser buser at stat.math.ethz.ch
Mon Sep 25 10:32:21 CEST 2006

Dear John


will help you.


Christoph Buser

Christoph Buser <buser at stat.math.ethz.ch>
Seminar fuer Statistik, LEO C13
ETH Zurich	8092 Zurich	 SWITZERLAND
phone: x-41-44-632-4673		fax: 632-1228

John Vokey writes:
 > useRs,
 >    A no doubt simple question, but I am baffled.  Indeed, I think I  
 > once knew the answer, but can't recover it.  The default contrasts  
 > for aov (and lm, and...) are contr.treatment and contr.poly for  
 > unordered and ordered factors, respectively.  But, how does one  
 > invoke the latter?  That is, in a data.frame, how does one indicate  
 > that a factor is an *ordered* factor such that contr.poly is invoked  
 > in the aov or lm call?
 > --
 > Please avoid sending me Word or PowerPoint attachments.
 > See <http://www.gnu.org/philosophy/no-word-attachments.html>
 > -Dr. John R. Vokey
 > ______________________________________________
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 > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
 > and provide commented, minimal, self-contained, reproducible code.

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