Center for Systemic Peace
Center for International Development and Conflict Management (CIDCM): Polity IV Project
The Polity data series, originally designed by Ted Robert Gurr, contains coded annual information on regime and authority characteristics for 161 independent states (fundamentally those with greater than 500,000 total population) in the global state system and covers the years 1800-2002. The Polity database is housed at Center for International Development and Conflict Management (CIDCM), at the University of Maryland, College Park series and is available at http://www.systemicpeace.org/polity/polity4.htm (current data for Polity Project moved to this website) . Monty Marshall has been kind in providing recent updates to the IFs project.
The Polity IV dataset provides substantial information on regime types and behavior. Polity codes were originally assigned according to three general categories of authority patterns: executive recruitment, executive constraints, and political competition. Later, these general categories were disaggregated into six component variables. IFs has drawn primarily on their indices of democracy and autocracy.