[BioC] GCRMA/RMA bimodal distribution

[Matthew Hannah]

Hi,

This has been mentioned before in the context of rma and that it was an
artifact of BG correction.

http://files.protsuggest.org/biocond/html/5066.html

I was very suprised to see that gcrma also gave a very pronouned bimodal
distribution. When comparing samples, obviously the relative positions
of the 2 peaks may influence observed expression changes. Would such
peak shifts be more likely in divergent samples, and if anyone wants to
comment on those.... ;-)

This example is using 12 chips (biological reps). But I initially
noticed it using 3 and 6 chips in rma.

Hope attachment works.

Cheers,
Matt


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