Résumé
Previous research shows that elected governments primarily follow the preferences of high-income citizens, but the reasons for this remain controversial. In the present paper, we introduce a new synthetic measure of electoral plutocracy, i.e. the relative electoral weight of the rich compared to the poor for a given government in a parliamentary regime. The index takes into account three sources of electoral distortion that may favor the rich: i) the conversion of persons into votes (turnout), ii) the conversion of votes into seats (representation), iii) the conversion of seats into government portfolios (coalition). Using survey data on parliamentary democracies since the late 1990s, we show that, on average, a person above the median income is electorally worth 1.16 times a person below the median income (and a person from the 10th decile is electorally worth 1.48 times a person from the 1st decile). This is mainly explained by higher turnout and higher participation in governing coalitions of parties supported electorally by the rich. Finally, we illustrate the interest of our index by re-testing the Meltzer-Richard hypothesis on the link between income inequality and redistribution. We show that the positive effect of inequality on redistribution is moderated by the level of electoral plutocracy.