Hi, everyone,

I am working on a dual-channel cDNA microarray project which includes 32
slides as a loop design. It is a 2x2x2x2 factorial experimental design that
combines 16 treatments. When I was trying to use modelMatrix to design the
matrix, it always asked me to input a reference. However, in my experiment,
I don't really have one as a reference. I tried to assign a random treatment
as reference but that way I couldn't make contrasts of the reference with
the other treatments. How should I set this argument? Is there a different
way that allows me not to assign a reference? Thanks.

Wei

-- 
Wei Xu
Aquatic Animal Health Laboratory
Pathobiology and Diagnostic Investigation
College of Veterinary Medicine
Michigan State University
East Lansing, MI, 48824
Tel: 1-517-432-8258

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