Political Analysis - Advance Access

Analyzing the U.S. Senate in 2003: Similarities, Clusters, and Blocs

Jakulin, A., Buntine, W., La Pira, T. M., Brasher, H. — 2009-06-30

In this paper, we apply information theoretic measures to voting in the U.S. Senate in 2003. We assess the associations between pairs of senators and groups of senators based on the votes they cast. For pairs, we use similarity-based methods, including hierarchical clustering and multidimensional scaling. To identify groups of senators, we use principal component analysis. We also apply a discrete multinomial latent variable model that we have developed. In doing so, we identify blocs of cohesive voters within the Senate and contrast it with continuous ideal point methods. We find more nuanced blocs than simply the two-party division. Under the bloc-voting model, the Senate can be interpreted as a weighted vote system, and we are able to estimate the empirical voting power of individual blocs through what-if analysis.

Modeling New Party Performance: A Conceptual and Methodological Approach for Volatile Party Systems

Mustillo, T. J. — 2009-06-26

This study of new political parties in the Third Wave democracies of Bolivia, Chile, Ecuador, and Venezuela conceptualizes the early life of a party as a developmental phase. The analysis uses latent trajectory modeling to identify five qualitatively distinctive performance profiles, which the author calls "explosive," "contender," "flash," "flat," and "flop" trajectories. This finding challenges the conventional approaches used in the study of new party performance, where scholars classify parties using subjective criteria, often into the successful/failed dichotomy. In unstable party systems, where we expect greater diversity in the performance profiles of new parties, latent trajectory modeling is preferred because it yields a result more consistent with extant theorizing on new parties. In stable systems, as in the case of Chile, the approaches can yield similar results. Nevertheless, the case of Venezuela (1958–88) demonstrates that even in stable party systems, the modeling approach used here can identify important variation that alternatives might miss.

Measuring Bias and Uncertainty in DW-NOMINATE Ideal Point Estimates via the Parametric Bootstrap

Carroll, R., Lewis, J. B., Lo, J., Poole, K. T., Rosenthal, H. — 2009-06-25

DW-NOMINATE scores for the U.S. Congress are widely used measures of legislators’ ideological locations over time. These scores have been used in a large number of studies in political science and closely related fields. In this paper, we extend the work of Lewis and Poole (2004) on the parametric bootstrap to DW-NOMINATE and obtain standard errors for the legislator ideal points. These standard errors are in the range of 1%–4% of the range of DW-NOMINATE coordinates.

Small Chamber Ideal Point Estimation

Peress, M. — 2009-06-24

Ideal point estimation is a topic of central importance in political science. Published work relying on the ideal point estimates of Poole and Rosenthal for the U.S. Congress is too numerous to list. Recent work has applied ideal point estimation to the state legislatures, Latin American chambers, the Supreme Court, and many other chambers. Although most existing ideal point estimators perform well when the number of voters and the number of bills is large, some important applications involve small chambers. We develop an estimator that does not suffer from the incidental parameters problem and, hence, can be used to estimate ideal points in small chambers. Our Monte Carlo experiments show that our estimator offers an improvement over conventional estimators for small chambers. We apply our estimator to estimate the ideal points of Supreme Court justices in a multidimensional space.

Dealing with Weak Instruments: An Application to the Protection for Sale Model

Gawande, K., Li, H. — 2009-06-24

Endogeneity of explanatory variables is now receiving the concern it deserves in the empirical political science literature. Instrumental variables (IVs) estimators, such as two-stage least squares (2SLS), are the primary means for tackling this problem. These estimators solve the endogeneity problem by "instrumenting" the endogenous regressors using exogenous variables (the instruments). In many applications, a problem that the IV approach must overcome is that of weak instruments (WIs), where the instruments only weakly identify the regression coefficients of interest. With WIs, the infinite-sample properties (e.g., consistency) used to justify the use of estimators like 2SLS are on thin ground because these estimators have poor small-sample properties. Specifically, they may suffer from excessive bias and/or Type I error. We highlight the WI problem in the context of empirical testing of "protection for sale" model that predicts the cross-sectional pattern of trade protection as a function of political organization, imports and output. These variables are endogenous. Importantly, the instruments used to solve the endogeneity problem are weak. A method better suited to exact inference with WIs is the limited information maximum likelihood (LIML) estimator. Censoring in the dependent variable in the application requires a nonlinear Tobit LIML estimator.

Predicting Presidential Elections with Equally Weighted Regressors in Fair's Equation and the Fiscal Model

Cuzan, A. G., Bundrick, C. M. — 2009-06-24

Three-decade-old research suggests that although regression coefficients obtained with ordinary least squares (OLS) are optimal for fitting a model to a sample, unless the N over which the model was estimated is large, they are generally not very much superior and frequently inferior to equal weights or unit weights for making predictions in a validating sample. Yet, that research has yet to make an impact on presidential elections forecasting, where models are estimated with fewer than 25 elections, and often no more than 15. In this research note, we apply equal weights to generate out-of-sample and one-step-ahead predictions in two sets of related presidential elections models, Fair's presidential equation and the fiscal model. We find that most of the time, using equal weights coefficients does improve the forecasting performance of both.

Giving Order to Districts: Estimating Voter Distributions with National Election Returns

Kernell, G. — 2009-04-29

Correctly measuring district preferences is crucial for empirical research on legislative responsiveness and voting behavior. This article argues that the common practice of using presidential vote shares to measure congressional district ideology systematically produces incorrect estimates. I propose an alternative method that employs multiple election returns to estimate voters’ ideological distributions within districts. I develop two estimation procedures—a least squared error model and a Bayesian model—and test each with simulations and empirical applications. The models are shown to outperform vote shares, and they are validated with direct measures of voter ideology and out-of-sample election predictions. Beyond estimating district ideology, these models provide valuable information on constituency heterogeneity—an important, but often immeasurable, quantity for research on representatives’ strategic behavior.