Dear List, I have applied "vsnrma" commpand to an affybatch object. But for the same object, if I run multiple times vsnrma, it gives me different values. i.e. dat1<-vsnrma(obj) dat2<-vsnrma(obj) dat3<-vsnrma(obj) dat1,dat2,and dat3 are different. It's not just numerically marginally different, but rather larget different. for example, probe A, for dat1, the value is 3, dat2 is 4, dat3 is 5. Could Wolfgang or someone explain this to me? Is there a way to seed a value and make the results same? Thank you. Xiaokuan [[alternative HTML version deleted]]