Abstract
Political sophistication (PS) is key concept for explaining political attitudes and voting behavior. The standard approach for measuring PS is to combine several question items from survey data to generate an index. In this process, much information is lost, obscuring the interpretation of PS. In this paper, we expressly evaluate the questions items used to measure political sophistication by employing item response theory. We test the new index by examining its effect on the stability of political attitudes. The results suggest that higher PS produces higher stability of ideological position and in the sense of duty of voting participation. However, higher PS produces greater instability in the level of political efficacy.
