[BioC] compare expression measures

[Jenny Drnevich]

Hi Mohammad,

If you look at the description of the functions ?rma and ?mas5 , you'll see 
that RMA gives you the log2 values, whereas MAS5 leaves the values in the 
original scale. Use this to convert the MAS5 values into log2 scale 
(mas5.demo is an eset):

exprs(mas5.demo) <- log2(exprs(mas5.demo))

Cheers,
Jenny


At 01:57 PM 1/4/2006, Mohammad Esad-Djou wrote:

>Hello,
>
>I wants to compare expression measures, which was computed with MAS and RMA.
>
>But I noticed that the expression-values are very different.
>
>e.g.: Expt1_R1.CEL: Gen: 1007_s_at
>
>RMA: 8,06941
>
>MAS: 236,16853028
>
>1. How can I interpret this difference?
>2. And which mathematical methods for comparison between preprocessing can 
>I use?
>
>thanks,
>Mohammad Esad-Djou
>
>Interdisciplinary Centre for Bioinformatics
>Leipzig, Germany
>
>
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Jenny Drnevich, Ph.D.

Functional Genomics Bioinformatics Specialist
W.M. Keck Center for Comparative and Functional Genomics
Roy J. Carver Biotechnology Center
University of Illinois, Urbana-Champaign

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e-mail: drnevich at uiuc.edu