Political Analysis - Advance Access

The Effect of Misclassifications in Probit Models: Monte Carlo Simulations and Applications

Hug, S. — Fri, 20 Nov 2009 05:37:18 PST

The increased use of models with limited-dependent variables has allowed researchers to test important relationships in political science. Often, however, researchers employing such models fail to acknowledge that the violation of some basic assumptions has in part difference consequences in nonlinear models than in linear ones. In this paper, I demonstrate this for binary probit models in which the dependent variable is systematically miscoded. Contrary to the linear model, such misclassifications affect not only the estimate of the intercept but also those of the other coefficients. In a Monte Carlo simulation, I demonstrate that a model proposed by Hausman, Abrevaya, and Scott-Morton (1998, Misclassification of the dependent variable in a discrete-response setting. Journal of Econometrics 87:239–69) allows for correcting these biases in binary probit models. Empirical examples based on reanalyses of models explaining the occurrence of rebellions and civil wars demonstrate the problem that comes from neglecting these misclassifications.

Finding Jumps in Otherwise Smooth Curves: Identifying Critical Events in Political Processes

Ratkovic, M. T., Eng, K. H. — Thu, 19 Nov 2009 06:30:28 PST

Many social processes are stable and smooth in general, with discrete jumps. We develop a sequential segmentation spline method that can identify both the location and the number of discontinuities in a series of observations with a time component, while fitting a smooth spline between jumps, using a modified Bayesian Information Criterion statistic as a stopping rule. We explore the method in a large-n, unbalanced panel setting with George W. Bush's approval data, a small-n time series with median DW-NOMINATE scores for each Congress over time, and a series of simulations. We compare the method to several extant smoothers, and the method performs favorably in terms of visual inspection, residual properties, and event detection. Finally, we discuss extensions of the method.

Strategic Voting in Plurality Elections

Kselman, D., Niou, E. — Thu, 12 Nov 2009 09:02:57 PST

This paper extends the Calculus of Voting of McKelvey and Ordeshook, providing the first direct derivation of the conditions under which voters will vote strategically: choose their second-most preferred candidate in order to prevent their least-preferred candidate from winning. Addressing this theoretical problem is important, as nearly all empirical research on strategic voting either implicitly or explicitly tests hypotheses which originate from this seminal model. The formal result allows us to isolate the subset of voters to which strategic voting hypotheses properly apply and in turn motivates a critical reevaluation of past empirical work. In making this argument, we develop a unified and parsimonious framework for understanding competing models of tactical voter choice. The typology helps to elucidate the methodological difficulties in studying tactical behavior when faced with heterogeneous explanatory models and suggests the need for both theoretical caution and more precise data instruments in future empirical work.

When Should Political Scientists Use the Self-Confirming Equilibrium Concept? Benefits, Costs, and an Application to Jury Theorems

Lupia, A., Levine, A. S., Zharinova, N. — Tue, 06 Oct 2009 06:59:21 PDT

Many claims about political behavior are based on implicit assumptions about how people think. One such assumption, that political actors use identical conjectures when assessing others’ strategies, is nested within applications of widely used game-theoretic equilibrium concepts. When empirical findings call this assumption into question, the self-confirming equilibrium (SCE) concept provides an alternate criterion for theoretical claims. We examine applications of SCE to political science. Our main example focuses on the claim of Feddersen and Pesendorfer that unanimity rule can lead juries to convict innocent defendants (1998. Convicting the innocent: The inferiority of unanimous jury verdicts under strategic voting. American Political Science Review 92:23–35). We show that the claim depends on the assumption that jurors have identical beliefs about one another’s types and identical conjectures about one another’s strategies. When jurors’ beliefs and conjectures vary in ways documented by empirical jury research, fewer false convictions can occur in equilibrium. The SCE concept can confer inferential advantages when actors have different beliefs and conjectures about one another.