[R] contrasts in aov
vokey at uleth.ca
Sat Sep 23 06:49:21 CEST 2006
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.
-Dr. John R. Vokey
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