\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, June 26, 2001} \centerline{Sequoia Hall Rm. 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} \centerline{\sl Stanford, CA 94305} \bigskip \centerline{\bf Microarrays, Empirical Bayes Methods, and False Discovery Rates} \bigskip In a classic two-sample problem we might for example use Wilcoxon's statistic to test for a difference between Treatment and Control subjects. The analogous microarray experiment would yield thousands of Wilcoxon statistics, one for each gene on the array, and we would be faced with a difficult simultaneous inference situation. We will discuss two inferential approaches to this problem: an empirical Bayes method that requires very little a priori Bayesian modeling, and the frequentist method of "False Discovery Rates" proposed by Benjamini and Hochberg in 1995. It turns out that the two methods are very closely related and can be used together to produce sensible simultaneous inferences. (This is joint work with Rob Tibshirani and John Storey.) \bye