Comparing Floor-Dominated and Party-Dominated Explanations of Policy Change in the House of Representatives

We test two explanations of the legislative process for their ability to account for the ideological pattern of policy change produced by bills enacted by the House of Representatives, 1953–1996. The Floor-Dominated explanation argues that the floor’s median member largely determines legislative outcomes, while the Party-Dominated explanation claims that power for the majority party. We develop three measures of the ideological pattern of policy change and independent variables that reflect the predictions of the two explanations. While we find support for both explanations, the greater significance, both substantively and statistically, of the Party-Dominated explanation leads us to conclude that the House’s agenda-setting process is largely controlled by the majority party. Scholars have long debated the relative influence of the floor median member and the majority party on the House of Representatives. We derive hypotheses from both theories about the ideological direction in which bills enacted by the House should change policy. We have created a data set for 1953–1996 that locates each enacted bill relative to the status quo policy that it challenges, which enables us to determine the ideological direction of the policy change produced by each bill. We aggregate these bills by year to identify annual patterns in the ideological directions of policy change. We then test each theory’s predictions with these data. In the first section we present our theoretical framework, describing our assumptions about the House’s legislative process and identifying each theory’s hypotheses about the ideological pattern of policy change. Next, we present three measures of the ideological direction of policy change, as well as our causal and control variables. We then offer our findings. Finally, we reflect on the relative efficacy of the two theories, concluding that the majority party is the most important determinant of the ideological pattern of policy change in the House