Measuring presidential powers: some pitfalls of aggregate measurement

Abstract

The purpose of this article is to address the issues of validity and reliability in existing additive indices measuring the strength of executives. Many data efforts, such as Frye et al. (2000) as well as Armingeon and Careja (2007), propose indices of presidential power based on a simple accumulation of a set of individual constitutional prerogatives allotted to the head of state according to the design proposed by Shugart and Carey (1992). These indices usually gather and count the powers of presidents on package and partial vetoes, decrees, budgetary powers, referenda provisions, initiation of legislation, cabinet formation, cabinet dismissal, censure, and the dissolution of assemblies. Despite the general acceptance of such measures of presidential power and their widespread use, empirical investigations to ascertain the degree to which existing indices measure a single latent construct, and are valid and reliable, were never conducted. In this article, I refute the assumptions of unimodality and unidimensionality underlying these indices, and challenge their usefulness in allowing researchers to differentiate between presidential, semi-presidential, and parliamentary institutional arrangements. (author's abstract)