Dear all, I was trying to normalize a subset of affy data those transcribe are either P or M (called pm_filter). I am able to normalize pm_filter subset by using RMA method, however MAS5 is not working. For RMA method, I used the following commend: est<-rma(affydata,subset=pm_filter). Could any help me; how do I do this by using MAS5 method? Regards, Anup Som Rostock, Germany -- output of sessionInfo(): My help function is not working. How do I fix it? ?rma Error in shell.exec(url) : 'http://127.0.0.1:30757/library/affy/html/rma.html' not found -- Sent via the guest posting facility at bioconductor.org.