[R] fractional factorial design in R
Martin Maechler
maechler at stat.math.ethz.ch
Sat Jan 21 09:33:20 CET 2006
>>>>> "BertG" == Berton Gunter <gunter.berton at gene.com>
>>>>> on Fri, 20 Jan 2006 14:15:49 -0800 writes:
BertG> I'm not sure what you mean by a "fractional
BertG> factorial" design here.
it's a pretty well known term, in (at least some schools of)
classical analysis of variance, e.g.
in the famous "Box, Hunter^2" (1987) book which had a 2nd
edition last year (Wiley), see also Doug Bates's nice account on
a talk about it,
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/29768.html
and the R package "BHH2" which is devoted to the book (2nd Ed).
BHH2 has a function ffDesMatrix() for fractional factorial
designs, *and* in it's see also section a link to the
conf.design() function in the package of the same name which
allows to construct ff designs (via different specifications).
see e.g, http://finzi.psych.upenn.edu/R/library/BHH2/html/ffDesMatrix.html
BertG> In general, when dealing with complex designs of the sort you appear to be thinking
BertG> about, small orthogonal designs don't exist. You
BertG> might wish to look at the AlgDesign package to
BertG> generate an efficient design to estimate only main
BertG> effects.
BertG> -- Bert Gunter Genentech Non-Clinical Statistics
BertG> South San Francisco, CA
BertG> "The business of the statistician is to catalyze the
BertG> scientific learning process." - George E. P. Box
now, since you have this nice signature, maybe you should
get the above book? ;-) :-)
>> -----Original Message----- From:
>> r-help-bounces at stat.math.ethz.ch
>> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of
>> Roberto Furlan Sent: Friday, January 20, 2006 12:37 PM
>> To: r-help at stat.math.ethz.ch Subject: [R] fractional
>> factorial design in R
>>
>> Hi, i need to create a fractional factorial design
>> sufficient to estimate the main effects. The factors may
>> have any number of levels, let's say any number from 2 to
>> 6. I've tried to use the library conf.design , but i
>> cannot figure out how to write the code. For example,
>> what is the code for a design with 5 factors (2x3x3x5x2)
>> and only main effects not confounded?
>>
>> thanks in advance! Roberto Furlan University of Turin,
>> Italy
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