Thank you to everyone who helped me with these problems - Chuck Berry, Marcus Davy, and especially Gordon Smyth. The bottom line seems to that statistics has its limitations and needs to be combined with the biology of the experiment. Naomi S. Altman 814-865-3791 (voice) Associate Professor Bioinformatics Consulting Center Dept. of Statistics 814-863-7114 (fax) Penn State University 814-865-1348 (Statistics) University Park, PA 16802-2111