[BioC] compare expression measures

Jenny Drnevich drnevich at uiuc.edu
Wed Jan 4 22:30:44 CET 2006

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))


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

>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?
>Mohammad Esad-Djou
>Interdisciplinary Centre for Bioinformatics
>Leipzig, Germany
>Erweitern Sie FreeMail zu einem noch leistungsstarkeren E-Mail-Postfach!
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>Bioconductor at stat.math.ethz.ch

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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1201 W. Gregory Dr.
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e-mail: drnevich at uiuc.edu

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