Hi; Does anybody have any suggestion/experience/reference on choosing a normalization method for data sets from different labs, generally speaking, which of the currently available methods works the best in this scenario. One more question, if we want to combine/compare new chip datasets with the old ones, do we have to normalize ALL data sets together again and again whenever we have new ones coming? Is there any reference or research results that we can, sort of, normalize only the new chips, but with respect to the old ones, so that they are comparable. I am sorry if this question doesn't qualify for this mail list, but I believe people on this lists know much more about microarray data analysis than other communities. Thank you all in advance! Fangxin -- Fangxin Hong, Ph.D. Plant Biology Laboratory The Salk Institute 10010 N. Torrey Pines Rd. La Jolla, CA 92037 E-mail: fhong@salk.edu