Finding DORI: Using Item Response Theory to Measure Difficulty of Registration in the U.S. and Its Impact on Voters

Abstract

How do states differ in how difficult they make voter registration, and what effect does this have on voters? We propose and validate a new Difficulty of Registration Index (DORI) calculated via an item response theory (IRT) model of five key dimensions of registration (automaticity, portability, deadline, mode, and preregistration) for each state from 2004 to 2020. Since 2004, most states eased registration processes, with Democratic statehouses in racially diverse and young states leading the way. Using CCES data, we find that DORI is associated with increased probability that voters experience problems registering and failing to turnout (in both self-reported and validated turnout data). These effects are pronounced for young voters. This study holds lessons for how restrictive registration procedures can change the shape of the electorate and make it harder to achieve political equality.