International Journal of Public Opinion Research ß The Author 2014. Published by Oxford University Press on behalf of The World Association for Public Opinion Research. All rights reserved. doi:10.1093/ijpor/edu002 Measuring Traits and States in Public Opinion Research: A Latent State–Trait Analysis of Political Efficacy Frank M. Schneider 1 , Lukas Otto 1 , Daniel Alings 1 and Manfred Schmitt 2 1 Department of Communication Psychology and Media Education, University of Koblenz-Landau, Germany and 2 Department of Psychology, University of Koblenz-Landau Abstract Latent state–trait theory (LSTT) considers the fact that measurement does not take place in a situational vacuum. LSTT decomposes any observed variable into a latent state component and a measurement error component, and any latent state into a latent trait component and a latent state residual representing situational influence and/or interactional influences. Furthermore, it provides more precise reliability estimates than common coefficients. This article introduces the basic concepts of LSTT, discusses its usefulness for public opinion research, and applies LST models to panel data on pol- itical efficacy from the 2009 German Longitudinal Election Study. The findings show that internal efficacy is a rather trait-like disposition and external efficacy is significantly due to situational and/or interactional influences. The distinction between traits and states has a long history and goes back to 45 B.C., when Cicero distinguished between trait-anxiety and state-anxiety (Eysenck, 1983). Not only are these concepts long-standing, they are still relevant for psychology today; in fact, (personality) traits also play a crucial role in public opinion research. Entire textbooks, such as Measures of Political Attitudes by Robinson, Shaver, and Wrightsman (1999), are dedicated to the measurement of relatively enduring and cross-situationally consistent person- ality characteristics (i.e., traits). With regard to public opinion research, the role of traits has been investigated in a vast number of studies: Besides the usual, domain-specific constructs, such as attitudes towards controversial social All correspondence concerning this article should be addressed to Frank M. Schneider, Institute of Media and Communication Studies, University of Mannheim, Haus Oberrhein, Rheinvorlandstr. 5, 68159 Mannheim, Germany. E-mail: frank.schneider@uni-mannheim.de. International Journal of Public Opinion Research Advance Access published March 5, 2014 by guest on March 6, 2014 http://ijpor.oxfordjournals.org/ Downloaded from