\magnification=1200 \baselineskip=20pt \nopagenumbers \font\big=cmr12 scaled \magstep2 \centerline{\bf STANFORD UNIVERSITY} \centerline{\bf DEPARTMENT OF STATISTICS} \centerline{\big DEPARTMENTAL SEMINAR} \bigskip \baselineskip=12pt \centerline{4:15 p.m., Tuesday, May 13, 2003} \centerline{Sequoia Hall Room 200} \centerline{(Cookies at 3:45 in 1st Floor Lounge)} \bigskip \baselineskip=15pt \centerline{\sl Bradley Efron} \centerline{\sl Department of Statistics} \centerline{\sl Stanford University} \bigskip \centerline{\bf Large-Scale Simultaneous Hypothesis Testing} \bigskip Abstract: "Multiple comparisons" used to mean doing 2 or 3 or 10 hypothesis tests at the same time. Now statisticians need to consider 500 or 5000 testing situations simultaneously, in microarray or frmi analyses for example. New problems and new opportunities arise in these contexts. I will discuss an empirical Bayes approach, related to false discovery rates, focusing on the choice of an appropriate null hypothesis for large-scale hypothesis testing. Two genomics examples will be used to motivate the methodology. This is joint work with Rob Tibshirani. \bye