\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, February 11, 2003} \centerline{Sequoia Hall Room 200} \centerline{(Cookies at 3:45 in 1st Floor Lounge)} \bigskip \baselineskip=15pt \centerline{\sl Jerome Sacks} \centerline{\sl NISS} \bigskip \centerline{\bf Statistical validation of computer models} \bigskip The use of mathematically based computer models for the study of scientific and engineering processes is ubiquitous. The most basic question in evaluating such a model is: "Does the computer model adequately represent reality?" Statistical methodology for addressing this question will be described within the context of test-bed problems. The proposed six-step strategy deals with major issues associated with a validation process: quantifying the typically multiple sources of error and uncertainty in computer models, combining multiple sources of information (e.g., from field experiments and computer runs), calibrating parameters of the computer model, and assessing model predictions in untested situations. A combination of spatial and bayesian statistical tools provides the technical apparatus. \bye