The operationalization of democracy and the strength of the democratic peace: a test of the relative utility of scalar and dichotomous measures

Abstract

The idea that democracies are less apt to engage in conflict with each other is a central finding in international relations. Yet the operationalization of democracy in this literature has been relatively unreflective. Since the mid-1990s the majority of studies have used Polity. In this paper we raise substantial concerns about its use, notably that there is a mismatch between conceptualization of democracy as a regime type and using an interval scale to measure it. If our contention is correct, we would expect to find that models that use a dichotomous coding should either pro-vide different results from Polity or at minimum fit the data better. We then test this contention by comparing the results of tests of the democratic peace using Polity in its interval scalar form and several common dichotomous codings of democracy. The tests are supportive of the contention that dichotomous coding better captures the notion of “democracy.” At minimum we believe that findings using Polity should be verified for robustness using a dichotomous coding.