[R] fractional factorial design in R

Martin Maechler maechler at stat.math.ethz.ch
Mon Jan 23 18:08:20 CET 2006

>>>>> "MM" == Martin Maechler <maechler at stat.math.ethz.ch>
>>>>>     on Sat, 21 Jan 2006 09:33:20 +0100 writes:

>>>>> "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. 
and Bert was right on target.
Please apologize for the following, which I'm now sure Bert
knows probably much better than me.

    MM> it's a pretty well known term, in (at least some schools of)
    MM> classical analysis of variance, e.g. 
    MM> in the famous "Box, Hunter^2" (1987) book which had a 2nd
    MM> edition last year (Wiley), see also Doug Bates's nice account on
    MM> a talk about it,
    MM> http://finzi.psych.upenn.edu/R/Rhelp02a/archive/29768.html
    MM> and the R package  "BHH2"  which is devoted to the book (2nd Ed).

    MM> BHH2 has a function  ffDesMatrix()  for fractional factorial
    MM> designs, *and* in it's see also section a link to the
    MM> conf.design() function in the package of the same name which
    MM> allows to construct ff designs (via different specifications).
    MM> 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
    MM> now, since you have this nice signature, maybe you should
    MM> get the above book? ;-) :-)
which was supposed to be something like a joke;  
given my misreading of Bert's comment, I'm sorry about it.

I have no good excuse for my blunder:
  It was Saturday morning, 
  I had slept well, 
  had had a shower, coffee and breakfast, ...  

Martin Maechler, ETH Zurich

    >>> -----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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