Gabor Grothendieck wrote:
I found this link:
http://webs.edinboro.edu/EDocs/SPSS/SPSS%20Regression%20Models%2013.0.pdf
which indicates that the contrast in SPSS that is used
depends not only on the contrast selected but also on the
reference category selected and the two can be chosen
independently. Thus one could have simple/first, simple/last,
deviation/first, deviation/last, etc. An R contr.SPSS function
would have to specify both the deviation type and the
first/last in order to handle all SPSS variations.
Not sure about "have to"; if so, contr.SAS also needs extension since
SAS does different things in different procedures (the help file does
say so).
Notice, BTW, that the cited reference defines contrast matrices
inversely to R (it maps from group levels to parameters).
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
