The Nationalization of State Interest Group System Density and Diversity

The authors replicate and extend their previous cross-sectional findings on state interest group system density and diversity by demonstrating that their models are useful in understanding change in diversity and density over time. In addition to developing and testing change score analogs of the models, they incorporate into each a homeostatic change process. The results not only support the core of the models but suggest that the unusually rapid growth in the number of groups over this period rendered state interest group systems far more homogeneous in terms of their responsiveness to the variables identified in the previous models.