Replication Data for: The Dynamics of State Policy Liberalism, 1936--2014

Applying a dynamic latent-variable model to data on 148 policies collected over eight decades (1936–2012), we produce the first yearly measure of the policy liberalism of U.S. states. Our dynamic measure of state policy liberalism marks an important advance over existing measures, almost all of which are purely cross-sectional and thus cannot be used to study policy change. We find that, in the aggregate, the policy liberalism of U.S. states steadily increased between the 1930s and 1970s and then largely plateaued. The policy liberalism of most states has remained stable in relative terms, though several states have shifted considerably over time. We also find surprisingly little evidence of multidimensionality in state policy outputs. Our new estimates of state policy liberalism have broad application to the study of political development, representation, accountability, and other important issues in political science.

本研究将动态潜变量模型（dynamic latent-variable model）应用于1936—2012年八十年间收集的148项政策数据，首次构建了美国各州政策自由主义程度的年度衡量指标。相较于现有衡量指标，我们提出的州政策自由主义动态衡量指标实现了重要突破——现有指标几乎均为纯横截面指标，无法用于研究政策变迁。研究发现，总体而言，美国各州的政策自由主义程度在1930年代至1970年代间稳步提升，随后基本趋于平稳。大部分州的政策自由主义程度在相对维度上保持稳定，但仍有部分州随时间推移发生了显著变化。此外，我们意外发现州政策产出的多维度性证据极为匮乏。我们提出的州政策自由主义全新估算结果，可广泛应用于政治发展、政治代表、问责机制及政治学领域其他重要议题的研究。