Dr. Garrett Glasgow (UCSB Political Science)

Title: New Empirical Strategies for the Study of Parliamentary Government Formation

ABSTRACT: In recent years a consensus has developed in political science that the conditional logit (CL) model is the most appropriate strategy for modeling parliamentary government choice (the choice of governing coalition after a parliamentary election). In this paper, we reconsider this approach and make three methodological contributions. First, we employ a mixed model with random coefficients (a mixed conditional logit) that allows us to take account of unobserved heterogeneity in the government formation process and relax the restrictive independence of irrelevant alternatives (IIA) assumption. Second, we demonstrate that the procedure used in the political science literature to test the IIA assumption is biased against finding IIA violations. An improved testing procedure reveals clear evidence of IIA violations, indicating that the CL model is inappropriate for the study of government formation. Third, we note that studies of government formation often contain tens of thousands of unique potential coalitions, most of which have near-zero predicted probability. Thus, substantive interpretation of these models poses a challenge. We develop several strategies for interpreting the substantive influence of variables in models of government choice, including javascript-based interactive graphs.