[R] What are Type II or III contrast? (contrast() in contrast package)

[Mitchell Maltenfort]

Thank you. I was already convinced of the value of MASS (drop a hat
and I'll tell you my other list of musts for a stats library) but I
didn't know about the Exegeses.


On Wed, Feb 3, 2010 at 3:12 AM, Emmanuel Charpentier
<charpent at bacbuc.dyndns.org> wrote:
> 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:
>> http://courses.washington.edu/b570/handouts/type3ss.pdf
>> http://core.ecu.edu/psyc/wuenschk/SAS/SS1234.doc
>> http://n4.nabble.com/a-kinder-view-of-Type-III-SS-td847282.html
>>
>> 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) :
>
> http://www.stats.ox.ac.uk/pub/MASS3/Exegeses.pdf
>
> (BTW, despite is age, MASS *is* requested reading, and Bill Venables'
> exegeses should be part of it).
>
> HTH,
>
> --
> Emmanuel Charpentier, DDS, MsC :-)
>
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