Gaussian mixture model of changes in alternative processing. Absolute expression of a hypothetical gene is reported by four independent probesets targeting different regions of this gene; I, II, III, IV (left panels) for control and treatment conditions (open and closed bars respectively). The idealized Gaussian mixture models representing changes in probeset behavior are illustrated in the right panels. Panels A, B, and C represent concordant probeset behaviors corresponding to no change, an increase, and a decrease, respectively. Panel D represents discordant behavior; two probesets (I, II) report an increase, while the remaining probesets (III, IV) report a decrease in expression between conditions (control and treatment). Probesets may report discrepant changes in gene expression depending on which region of the mRNA transcript they interrogate.