The Methodology of "Varieties of Democracy" (V-Dem)

This article describes and discusses the new generation of methodological responses to measuring democracy and related issues generated by Varieties of Democracy (V-Dem). V-Dem is distinct in several regards in addition to its unique level of disaggregation, by the combination of: historical data extending back to 1900 and for a large selection among them to 1789 for many countries in the world; use of multiple, independent coders for each evaluative question; inter-coder reliability tests incorporated into a custom designed Bayesian item-response theory measurement model; provision of confidence bounds for all point estimates associated with expert-coded questions as well as for all indices; multiple indices reflecting varying theories of democracy; fully transparent aggregation procedures; and that all data are made freely available, including original coder-level judgments (exclusive of any personal identifying information).