This textbook is designed to bridge the gap between the theorist and the methodologist by presenting an integrated approach to measurement. By differentiating between random and systematic error, it conveys both statistical techniques and their theoretical underpinnings essential to students of sociology and political science. Rather than developing new technical methods of new theoretical structures, Professors Zeller and Carmines provide thorough explanations of the assumptions, limitations and interpretations of previously established techniques and theories. Written at a level accessible to students of social science with some statistical training, the book does not presume a sophisticated mathematical background. By concentrating on synthesizing the methodological and theoretical realms, Zeller and Carmines demonstrate why measurement considerations are important to research and how measurement principles can be most effectively applied.