I found the answer to my questions on Dr. Irizarry's website in his talk: http://www.iobion.com/slides/RMA/rma.pdf Naomi S. Altman 814-865-3791 (voice) Associate Professor Dept. of Statistics 814-863-7114 (fax) Penn State University 814-865-1348 (Statistics) University Park, PA 16802-2111