An Ordinal Item Response Model for Understanding Attitudes

Abstract

We present an item response model for ordinal public opinion data to understand individual-level variation in attitudes as a function of covariates. The approach allows investigating how individuals (or population subgroups) differ in substantive stances about topics (or candidate evaluations) and attitude strength. We exemplify the types of substantive insights into heterogeneity in public opinion that can be obtained from the approach but not from existing models with two applications: attitudes toward gender equality (European Values Study) and the evaluation of candidate traits (American National Election Study).

Keywords: public opinion, attitudes, individual-level variation, item response theory, ordinal responses