Dear list:

I have a question about how to do expression microarray normalization when
doing group
comparisons. I have 40 individuals (20 cases, 20 controls) and each one has
3
mRNA chips at different time-points. Should I normalize all the chips
(40x3)
together (and the subset for each comparison) or if I am comparing
cases_time1 vs controls_time1, or cases_time1 vs
cases_time2, should I normalize only these 40 chips involved in this
particular comparison?  (I am working with Illumina chips)

I am new in the expression analysis and I would appreciate any comments
about
advantages or disadvantages regardind these two approaches.

Thank you very much!


 ANA BARBARA GARCIA
 Unidad de Genotipado y Diagnóstico Genético
 Valencia Clinical  Hospital Research Foundation
 CIBER of Diabetes and Metabolic Diseases

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