Abstract: A computer-implemented method and apparatus for correcting data sets from microarray measurements of gene expression values made with several different microarray versions. The method comprises obtaining data sets (210) of expression values of several genes of biological samples (202), made with several different microarray versions; normalizing (212) the data sets; determining a first gene-specific distribution parameter (220) for each microarray version and a second gene-specific distribution parameter (222) for a combination of microarray versions; determining a gene-specific correction element (226) for each microarray version based on the discrepancy (224) between the first and second gene-specific distribution parameters; correcting a gene's expression value with the gene-specific correction element (226) for the microarray version on which the gene's expression value is based; and storing (118) the gene's corrected expression value (228) in a physical memory (230).