Hello, I would like to combine about 50 ID's from the affymetrix HG-U133A chip with the corresponding probe ID's from the affymetrix HG-U95Av2 chip. I know what the corresponding probe-ID's on the U95Av2 chip are. But how do I combine the data from those 50 ID's from one affy object containing U133A chips with the data from the corresponding ID's in an affy object containing U95Av2 chips? Is this possible? If yes....how? Is it best to combine the data after scaling and normalization or before? Rudy van Eijsden. Maastricht University Cluster of Genetics and Cell Biology Department of Clinical Genetics E-mail rudy.vaneijsden@gen.unimaas.nl [[alternative HTML version deleted]]