A study by Martin Gilens of Princeton University and Benjamin Page of Northwestern University finds on the basis of multivariate analysis that the United States resembles an oligarchy because "economic elites and organized groups representing business interests have substantial independent impacts on US government policy, while average citizens and mass-based interest groups have little or no independent influence". Gilens and Page confirm the notion that factions have allowed politicians to act independently of their electorate:
Each of four theoretical traditions in the study of American politics--which can be characterized as theories of Majoritarian Electoral Democracy, Economic-Elite Domination, and two types of interest-group pluralism, Majoritarian Pluralism and Biased Pluralism--offers different predictions about which sets of actors have how much influence over public policy: average citizens; economic elites; and organized interest groups, mass-based or business-oriented.
Martin Gilens and Benjamin Page, ‘Testing Theories of American Politics: Elites, Interest Groups and Average Citizens’ (Sep 2014) Perspectives on Politics, Vol. 12, No. 3.