\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, October 2, 2001} \centerline{Sequoia Hall Rm. 200} \centerline{(Cookies at 3:45 in 1st Floor Lounge)} \bigskip \baselineskip=15pt \centerline{\sl Peter Bartlett} \centerline{\sl Department of Statistics} \centerline{\sl University of California, Berkeley} \bigskip \centerline{\bf Error Estimation with Rademacher and Gaussian Complexities} \bigskip We investigate model selection strategies based on penalized empirical loss minimization. We point out a tight relationship between error estimation and data-based complexity penalization: any good error estimate may be converted into a data-based penalty function and the performance of the estimate is governed by the quality of the error estimate. We focus in particular on Rademacher and gaussian complexities, and show how estimates of these complexities can be computed. We give examples of the application of these techniques in finding data-dependent error estimates for decision trees, neural networks and support vector machines. (Joint work with Stephane Boucheron, Gabor Lugosi, and Shahar Mendelson.) \bye