[R] What are Type II or III contrast? (contrast() in contrast package)
charpent at bacbuc.dyndns.org
Wed Feb 3 09:12:21 CET 2010
Le mercredi 03 février 2010 à 00:01 -0500, David Winsemius a écrit :
> On Feb 2, 2010, at 11:38 PM, Peng Yu wrote:
> > ?contrast in the contrast package gives me the following description.
> > However, I have no idea what Type II and III contrasts are. Could
> > somebody explain it to me? And what does 'type' mean here?
> > *‘type’*: set ‘type="average"’ to average the individual contrasts
> > (e.g., to obtain a Type II or III contrast)
> In no particular order:
> Don't expect any follow-up questions to be answered or further
> citations offered. This is really more in the realm of statistics
> education than an R specific question.
Nonwhistanding David Winsemius' closing remark, I'd like to add
something that should be requested reading (and maybe hinted at in
lm()'s help page) :
(BTW, despite is age, MASS *is* requested reading, and Bill Venables'
exegeses should be part of it).
Emmanuel Charpentier, DDS, MsC :-)
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