[BioC] compare expression measures

[James W. MacDonald]

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?

RMA returns log2 transformed data, so you either have to take the 
logarithm for your MAS data, or 'unlog' the RMA data.

Jim



> 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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-- 
James W. MacDonald
University of Michigan
Affymetrix and cDNA Microarray Core
1500 E Medical Center Drive
Ann Arbor MI 48109
734-647-5623



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