[BioC] negative expression values

[Arne.Muller at aventis.com]

Hello,

I'm analysing a set of expression data that were processed (normalized) in Rosetta Resolver version 4. I've exported the data into R to run linear model + anova with 3 factors.

In Resolver expression values can be zero or negative - about 4 percent of the probesets in my data set.

I'd like to work with log2 transformed intensities, so I was wondering if there's anything speaking against shifting intensities, so that the minimal intensity is e.g. 1. The actual minimmal value is -106 and the maximum is about 14000.

	I'm happy to receive suggestions or comments,

	+regards,

	Arne

--
Arne Muller, Ph.D.
Toxicogenomics, Aventis Pharma
arne dot muller domain=aventis com