-----Original Message----- From: Stephen Henderson Sent: Monday, June 16, 2003 4:02 PM To: 'Park, Richard' Subject: RE: [BioC] normalize by or across all treatments I somewhat disagree--If you have meaningful contrasts (with 3 replicates) they will survive normalising all together. If you normalise separately you will almost certainly introduce false differences- and if you then try lots of ways you might find some you like. Stephen -----Original Message----- From: Park, Richard [mailto:Richard.Park@joslin.harvard.edu] Sent: Monday, June 16, 2003 3:56 PM To: Leanna House; bioconductor Subject: RE: [BioC] normalize by or across all treatments These are my two cents to the question. I would at first normalize everything together via rma, which does poses risks of diminishing or enhancing treatment effects. But I believe this would allow you to see the overall picture of the data and give you a general sense of how each treatment compares to each other and the control. And if you wanted to spend some more time, you could then try creating various data sets by using rma to normalize data between each treatment and the control and have 4 groups of data (each treatment normalized w/ the control). This would be a more specific analysis leaving out the enhancing or diminishing effects of normalization between many different treatments. Richard Park -----Original Message----- From: Leanna House [mailto:house@stat.duke.edu] Sent: Monday, June 16, 2003 10:25 AM To: bioconductor@stat.math.ethz.ch Subject: [BioC] normalize by or across all treatments In replicates of 3, I have a set of control and 4 treatment arrays. My question is, do I normalize (via rma) using all of the arrays at once, or do I normalize by treatment. I have asked other reliable sources and have received conflicting responses. I feel the issue is that, in one case, I may, if not completely wipe out, severely diminish any possible treatment effects, whereas, in the other case, I may actually induce a treatment effect. Any thoughts? Thank you so much, Leanna _______________________________________________ Bioconductor mailing list Bioconductor@stat.math.ethz.ch https://www.stat.math.ethz.ch/mailman/listinfo/bioconductor _______________________________________________ Bioconductor mailing list Bioconductor@stat.math.ethz.ch https://www.stat.math.ethz.ch/mailman/listinfo/bioconductor ********************************************************************** This email and any files transmitted with it are confidential an... {{dropped}}