We use two alternative measures of regime type. One is based on the Polity IV dataset, which contains separate 0– 10 measures of democracy and authoritarianism for each country-year; following standard practice, we combine these two measures to produce a 21-point scale, which we call POLITY.
The other measure allows for a country’s history of democratic rule to influence its infant and child mortality rates. Several recent studies suggest that new democracies perform less well than established ones (Keefer and Vlaicu 2005; McGuire 2006). A state with 50 years of democratic experience, for example, might reduce infant mortality more quickly (or slowly) than a country with just one year of democratic experience.13 To explore this possibility, we use a variable that is based on the total number of years that each country has been a democracy, beginning in 1900; we take the natural log of this figure (DEMOCRATIC YEARS) to capture the intuition that the marginal benefits of democracy will diminish over time.