One might worry, however, that this test is too lenient. The ideology-policy correlation is the dominant approach in studies of state responsiveness, and it has been the most fruitful approach to date. However, problems of inference arise because researchers cannot know exactly how diffuse preference measures ought to translate into policy. That is, policy and ideology lack a common metric (Erikson, Wright, and McIver 1993, 93;Matsusaka 2001 but without knowing the mapping of ideology to voter policy preferences, we cannot tell if policy is over-or underresponsive to preferences.Most existing work, by focusing on the ideologypolicy correlation, also does not assess how responsive states are to voter preferences on specific policies. Nor does it tell us how effective state political systems are at translating opinion majorities into public policy. If a majority of voters in a state wants to adopt a lottery or impose an abortion restriction, how likely is the state to do so? In other words, is policy usually congruent with majority will?Both responsiveness and congruence are forms of policy representation, but they capture different dimensions of democratic performance. To be clear, by responsiveness, we mean a positive correlation between opinion and policy; by congruence, we mean that policy actually matches majority opinion. Where majority will is truly sovereign, you would expect both strong responsiveness and a high level of congruence. Policy adoption may increase with higher public support (suggesting responsiveness), but policy may still often be inconsistent with majority opinion (suggesting a lack of congruence),