The Modifiable Areal Unit Problem in Political Science

Building on the availability of geospatial data, improvements in mapping software, and innovations in spatial statistics, political scientists are increasingly taking geography seriously. As we adopt the tools of geographers, we must also consider the methodological challenges they have identified. We focus on the modifiable areal unit problem (MAUP)-the idea that the size of aggregate spatial units and the location of their borders affect the empirical results we obtain. We first describe the logic of the MAUP, and then demonstrate the MAUP through simulations, showing MAUP-related inconsistency in regression results in randomly generated and real-world data. We identify MAUP concerns, and best practices, in top journals in political science. We conclude by suggesting how scholars may respond in theoretical and empirical terms to concerns about validity and reliability that arise from the MAUP.