Outline

RMA Model• To each probeset (k), with i being number ofprobes and j being number of chips, fit the model:y= α + β + ε( k) ( k) ( k) ( k)ij i j ij( k) ( k)where αiis a probe effect and βjis the( k )log gene expression. yijis the log2 backgroundadjusted and normalized PM intensity• Different ways to fit this model– Median polish – quick– Robust linear model – yields some good qualitydiagnostic tools