[R] fractional factorial design in R

[Berton Gunter]

> 
> At the moment, I am using an SPSS function (orthoplan) for my 
> needs. It provides factorial design with only main effects 
> (small orthogonal designs).
> Since SPSS is very expensive (in particular with this 
> add-on), I would like to use R as for all my other projects 
> and research activity.

Yes, you're right. For, say, a 3 x 5 design, one can do this in as few as 7
runs -- but only in general by some version of one-factor-at-a-time (OFAT)
designs, which are inefficient.  It is easy, via, say model.matrix() to
write a general function to produce these. But I think it's a bad idea; more
efiicient algorithmic designs are better, IMO, which is why I suggested
AlgDesign. You and others are free to disagree, of course.

Cheers,
Bert


> 
> Do you know any other way to produce these designs in R?
> 
> Thanks in advance,
> 
> Roberto Furlan
> University of Turin, Italy
> 
> 
> 
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