[R] R: fractional factorial design in R

[statistical.model@googlemail.com]

Hi! 
thanks for your response!

>unfortunately, fractional factorial designs typically require all factors
to 
have the same number of levels. Hence, your 2x3x3x5x2 example is not a
simple 
special case of a fractional factorial design. 
>There are some special plans for mixed level designs, but the conf.design 
function requires all factors to have the same number of levels, as you can 
also find in its help:
    p: The common number of levels for each factor.  Must be a prime 
          number.
>ffDesMatrix from package BHH2 is even worse, since it requires all factors
to 
have 2 levels:
    k: numeric. The number of 2-levels design factors in the
          designs. 


I've tried both ffDesMatrix and conf.design and i realized that they cannot
help me for the problem above.

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.

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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