Conceptualizing, Measuring, and Mapping State Structures — With an Application To Western Europe, 1950 – 2015

This article addresses long-standing challenges in conceptualizing and measuring decentralization in unitary and federal systems. It first outlines a novel conceptualization of decentralization and its relation to the unitary/federal distinction and a/symmetry, from which it derives static and dynamic typologies of state structures. Building on a critical review of the Regional Authority Index, the article develops a scheme for measuring decentralization and applies it to map state structures in Western Europe from 1950 to 2015.This mapping exercise shows that the proposed scheme yields more accurate measures of decentralization than existing indices and that decentralization differs in kind, rather than merely in degree, between unitary and federal states. By enabling a more effective classification of cases in comparative analysis, the article offers a tool on which theoretical and empirical advances in understanding the causes and effects of state structures can be built