\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 8, 2001} \centerline{Sequoia Hall Rm. 200} \centerline{(Cookies at 3:45 in 1st Floor Lounge)} \bigskip \baselineskip=15pt \centerline{\sl Simon Jackman} \centerline{\sl Department of Political Science} \centerline{\sl Stanford University} \centerline{\sl Stanford, CA 94305} \bigskip \centerline{\bf Markov chain Monte Carlo in the Social Sciences} \bigskip By any reasonable standard, Markov chain Monte Carlo is one of the more important recent developments in applied statistics. After some initial resistence to MCMC's Bayesian underpinnings, MCMC is now widely accepted by quantitative social-scientists, providing an interesting case study in the cross-disciplinary proliferation of statistical ideas and methods. My focus is on examples from political science. Models and data sets that political scientists had long consigned to the ``too-hard'' basket are now easily handled via MCMC. Time permitting, examples to be discussed include (1) estimating the ideological location of politicians via analysis of their voting records (roll call data), using an analog of item-response models; (2) multivariate $t$ regression models for (heavy-tailed) multi-party electoral data; (3) dynamic hierarchical models for state-level election forecasting, using the 2000 U.S.~Presidential Election as an example; (4) mixture models for heterogeneity in survey-based measures of political attitudes; (5) parameter-driven transitional models of international conflict (correlated binary data). \bye