Performance improvements on blood samples data set. (a) ROC curve for replication of case–control differences between blood samples from colon cancer patients and blood samples from normal individuals, the Ontario-Blood data set. The validation data set was constructed to show an in silico batch effect. (b) ROC curve for identification of probes on the sex chromosomes for the Ontario-Sex data set. Sex is confounded by an in silico batch effect. Both evaluations show the good performance of functional normalization. Funnorm, functional normalization; ROC, receiver operating characteristic.