Dear BioC, we have a microarray experiment design for which we will retrieve more samples in future. To have consistent analysis I would like to set a reference sample in dataset now available, and then use it for also for later experiments. We are using affymetrix platform, so I would like to know if any normalization implemented in affy permits this operation, and how to do this. I know Dchip permits to make this choice, so I guess the Invariant set implementation should give this opportunity, but I did not find out how to to this. thank you -- John Lande [[alternative HTML version deleted]]