The public and the media commonly refer to members of the United States Congress and other legislatures as "liberals" and "conservatives". The fundamental concern of this project is to provide accurate measurement of liberal/conservatism. As a result of our development of the NOMINATE scaling algorithm in the 1980s, political scientists and economists have used our measurements of Congress in scores of professional publications and used our algorithms as measurement techniques for dozens of other legislatures, ranging from state legislatures in the United States to foreign parliaments to the United Nations General Assembly. The measurements are frequently used in teaching American political history and in introductory courses on American politics.
This project increased the accuracy of measurement for Congress and updated the database current. Moreover, the work on other legislatures has suggested that the decision-making model that underpins NOMINATE does not always extend to other legislatures. Left-right (or liberal-conservative) preferences may be more sharply defined than in Congress. Abstention, as well as Yea and Nay, may be a meaningful choice. The project also provided work on estimation methods that allow for a more general approach to legislative behavior.
A unique feature of our work is that its dynamic feature permits comparisons of liberal/conservatism over time. For example, others have used these measurements to study the evolution of slavery as an issue in congressional politics in the nineteenth century and trade legislation, including reciprocal tariffs and fast track, throughout American history. This dynamic feature allows us to work on models with time-dependent preferences and on supercomputing techniques for large-scale computation.
