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

[Peng Yu]

On Wed, Feb 3, 2010 at 2:12 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).

Do you by any means indicate that MASS describes Type I, II, III, IV
contrast? Although MASS describes contrasts, but I don't think it
describes Type I, II, III, IV contrast.