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The SAGE Handbook of Political Science, Vol. 1(2), March 2020, ch.22.

The past twenty years have witnessed a sharp increase in the use of experimentation in political science, from field experiments to on-line experimental surveys. This chapter provides a review of the theoretical foundations, the advantages, and the challenges of the experimental methodology both in theory and in practice. Instead of providing a broad analysis of all types of experimental studies, I focus on political economy experiments: incentivized, controlled, laboratory experiments which main goal is to test theoretical predictions and conjectures. I discuss the conceptual features that set political economy experiments apart from other types of experiments and offer a glimpse on the development of this methodology.

Weather, Risk, and Voting: an Experimental Analysis of the Effect of Weather on Vote Choice

The Journal of Experimental Political Science, Vol. 6(1), Spring 2019, 17–32.

A number of theoretical and empirical studies analyze the effect of inclement weather on voter turnout and in turn on parties’ vote share. However, empirical findings suggest that the effect of weather on parties’ vote share is greater than can be explained by its influence on voter turnout alone. This paper provides experimental evidence of the effect of weather on vote choice between more- versus less-risky candidates. Findings show that bad weather depresses risk tolerance, that is, voters are less likely to vote for risky candidates. This effect is sizable and statistically significant.

Policy Preferences in Coalition Formation and the Stability of Minority and Surplus Governments

The Journal of Politics, Vol. 79(1), January 2017, 250–68.

In parliamentary democracies, political parties bargain over cabinet portfolios when forming coalition governments. While most of the theoretical literature predicts that only minimal winning coalitions form in equilibrium, the empirical evidence shows that minority and surplus coalitions are about as frequent. In this article, I bridge the gap between the theoretical predictions and the empirical evidence by developing a non-cooperative bargaining model in which parties are both office seeking and policy pursuing. Parties bargain over cabinet portfolios, which in turn determines the government policy. Parties are farsighted, and when they coalesce with other parties, they take into account not only the expected cabinet portfolio allocation, but also how this allocation would affect the government coalition policy. The model predicts in equilibrium the formation of minimal winning as well as minority and surplus coalitions as a function of a
party’s size, ideal policies, and relative preference for policy versus office.

Voting Systems and Strategic Manipulation: an Experimental Study

Journal of Theoretical Politics, Vol. 27(1), January 2015, 58–85.

This article presents experiments that analyze the strategic behavior of voters under three voting systems: plurality rule, approval voting, and the Borda count. Applying a level-k reasoning model approach, strategic behavior is found to be significantly different under each treatment (voting system). Plurality rule leads voters to play in the most sophisticated (i.e. best response), but not necessarily insincere, manner. Thus, this voting system displays at the same time the highest incidence of best responses and of sincere votes. The opposite holds for the Borda count games, where voters depart from their sincere strategy the most, without playing the best response strategy. Approval voting shows intermediate levels of sophistication and sincere behavior.

Examining monotonicity and saliency using level-k reasoning in a voting game

Games, Vol. 5, 2014, 26–54.

This paper presents an experiment that evaluates the effect of financial incentives and complexity in political science voting experiments. To evaluate the effect of complexity we adopt a level-k reasoning model concept. This model (Nagel, 1995) postulates that players might be of different types, each corresponding to the level of reasoning in which they engage. Furthermore, to postulate the effect of financial incentives on subjects’ choice, we used the Quantal Response Equilibrium (QRE) concept. In a QRE, players’ decisions are noisy, with the probability of playing a given strategy increasing in its expected payoff. Hence, the choice probability is function of the magnitude of the financial incentives. Our results show that low complexity promotes the highest degree of level-k strategic reasoning in every payment treatment. Standard financial incentives are enough to induce equilibrium behavior, and the marginal effect of extra incentives on equilibrium behavior seems to be negligible. High complexity, instead, decreases the rate of convergence to equilibrium play. With a sufficiently high complexity, increasing payoff amounts does promote more strategic behavior in a significant manner. Our results show with complex voting games, higher financial incentives are required for the subjects to exert the effort needed to complete the task.

Coauthor: K. Williams

A Model of Endogenous Government Formation

The American Journal of Political Science, Vol. 57(4), October 2013, 777–793.

Political parties bargain over the allocation of cabinet portfolios when forming coalition governments. Noncooperative theories of legislative bargaining typically predict that the “formateur” enjoys a disproportionate share of government ministry positions. However, empirical evidence indicates that parties receive shares of portfolios proportional to their share of legislative seats that a government party contributes to the government coalition in support of Gamson’s Law of portfolio allocation. This article examines government formation as a process in which both the government coalition and the formateur are determined endogenously. In equilibrium, if parties have similar preferences over cabinet portfolios, the share of seats they are allocated is proportional to the parties’ sizes.

‘O Sole Mio. An Experimental Analysis of Weather and Risk Attitudes in Financial Decisions

The Review of Financial Studies, Vol. 26(7), July 2013, 1824–1852.

Although weather has been shown to affect financial markets and financial decision making, a still open question is the channel through which such influence is exerted. By employing a multiple price list method, this paper provides direct experimental evidence that sunshine and good weather promote risk-taking behavior. This effect is present whether relying on objective measures of meteorological conditions or subjective weather assessments. Finally, employing a psychological test, we find evidence that weather may affect individual risk tolerance through its effect on mood.

CoauthorR. Colacito and P. Fulghieri

The Effects of Identities, Incentives, and Information on Voting

The Journal of Politics, Vol. 73, No. 2, April 2011, Pp. 558-571.

We report on majority voting experiments where subjects are randomly assigned identities in common with a candidate. However, subjects sometimes receive a financial incentive from voting contrary to their identity. We vary the size of the incentive as well as information voters have about the advantage of the incentive. We find that subjects are influenced by their assigned identities, and the effect is stronger when voters have less information. Nevertheless, financial incentives reduce this influence when voters have full information. Our results suggest that identity may have an important affect on voter choices in elections where incentives or information are low.

Coauthor: R. Morton and K. Williams