QUANTITATIVE AND QUALITATIVE: A QUESTION OF COMPARABILITY Extended version of chapter published in International Encyclopedia of Political Science, Bertrand Badie, Dirk Berg-Schlosser, Leonardo Morlino (eds), Sage, 2011 John Gerring Professor Department of Political Science Boston University 232 Bay State Road Boston MA 02215 jgerring@bu.edu Craig W. Thomas Associate Professor Daniel J. Evans School of Public Affairs Box 353055 University of Washington Seattle, WA 98195-3055 206-221-3669 thomasc@washington.edu