The Dimensional Structure of Policy Outputs: Distributive Policy and Roll Call Voting

Policy proposals begin life in the legislative arena as high-dimensional ideas that are reduced to a single evaluative dimension by the time they are decided on the legislative floor. While roll-call decisions in Congress are largely unidimensional, little is known about the dimensional structure of policy outputs. Do policy outputs reflect a high-dimensional environment or a low-dimensional structure similar to the legislative floor? This article proposes a theory of policy outputs and investigates this question by examining the dimensional structure of policy outputs. The results indicate that outputs are fundamentally multidimensional. Policy proposals are dynamic through the legislative process. Yet most research assumes that proposals are static, usually defined as they appear on the legislative floor. Most research classifies legislation based on floor behavior using general ideology measures, such as liberal or conservative, and uses this classification to predict the policy consequences of the votes. But do legislative outputs reflect this simple classification? Case-study research suggests that legislators have different reasons for supporting legislation at different stages of the legislative process. The decision to cosponsor a bill is different from the decision to support the bill in committee, or to support the bill on the floor, or to support the public law. Thus, policy proposals are dynamic: they have different underlying dimensional structures as they progress through the legislative process (Hall 1996; Jones 1994; King 1997). While the literature has thoroughly investigated the floor decision stage of legislation, little is known about the output stage, particularly how policy outputs are linked to floor decisions. We propose a theory of legislative outcome space that focuses on how low dimensional legislative decisions become high dimensional policy outputs. Specifically, the question we investigate in this study is, does the dimensional structure of policy outcomes reflect the low dimensions that characterize legislators' voting, or a higher multidimensional process? The first section of this article examines why dimensions and dimensional structures matter for the study of policy and political representation. Next, we propose a theory of legislative decisions and outcomes to explain how policy outcomes relate to floor decisions and activities. The third section describes the distributive program awards data and the NOMINATE method used to evaluate the theory. The fourth section presents the results of our analyses. The article concludes with a discussion of the implications of this paper for studies of congress, agenda setting and representation, and offers avenues for future study. POLITICAL THEORY AND POLICY DIMENSIONS Policy proposals are inherently multidimensional. Following Riker, we define a dimension as "a standard of measurement for relevant variable properties of alternatives and tastes" (1986: 143). In other words, any policy proposal has multiple evaluative characteristics that individually, or in concert, form the basis for decisions. Identifying the number of dimensions in a set of issues can be accomplished by examining coalitions of legislators' preferences or decisions across the issues. A unidimensional issue context creates consistent coalitions of legislators on each side of all issue proposals, with the coalitions changing only as moderate legislators move to either the conservative or liberal coalition depending on how the particular proposal favors either side. A multidimensional issue context creates different patterns of coalitions for different issues. The coalitions vary depending on which dimensions are most salient for particular issues. For example, economic issues may pit a coalition of legislators favoring redistributing wealth against a coalition that favors laissez-faire economic policies. A different coalition pattern would surround social issues, such as abortion, perhaps pitting social conservatives (some of who may favor laissez-faire economics while others favor economic redistribution) against a coalition of social liberals (whose members may also contain both economic liberals and economic conservatives). …