Revisiting the impact of impure public goods on consumers’ prosocial behavior: A lab experiment in Shanghai

In this study, we implemented a dictator game experiment to examine how the increase of the public characteristic in an impure public good affects individuals’ prosocial behaviour. A within‐subject design was used in the experiment. The dictator game was repeated six times with an impure public good introduced in four of them. We observe that the increase of the public characteristic in an impure public good partly crowds out individuals’ subsequent donations, which could be explained by a seemingly ‘mental accounting’ mental process. In addition, we also find that the selfish behaviour of individuals in dictator games with impure public goods, to some extent, has an inertia influence on their subsequent donations when the impure public good is removed.     

Dragon Slaying with Ambiguity: Theory and Experiments

This paper studies the impact of ambiguity in the best‐shot and weakest‐link models of public good provision. The models are first analyzed theoretically. Then, we conduct experiments to study how ambiguity affects behavior in these games. We test whether subjects' perception of ambiguity differs between a local opponent and a foreign one. We find that an ambiguity‐safe strategy is often chosen by subjects. This is compatible with the hypothesis that ambiguity aversion influences behavior in games. Subjects tend to choose contributions above (respectively, below) the Nash equilibrium in the best‐shot (respectively, weakest‐link) model.     

Adoption externalities as public goods

A public good problem arises naturally in situations characterized by positive externalities or negative externalities. For positive externalities, agents furnish a public good by taking an action. Similarly, for negative externalities, agents furnish a public good by not taking an action. We examine these externalities in a binary choice problem, i.e. adoption externalities. In each case, there is a potential role for government intervention, even when equilibrium transfers are not allowed, since one equilibrium Pareto dominates all others. We analyze the positive and normative features of equilibria in these models, and we explore the possibility of useful government intervention.     

The strategic equivalence of rent-seeking, innovation, and patent-race games

We establish the strategic equivalence of a variety of rent-seeking contests, innovation tournaments, and patent-race games. The results allow us to disentangle negative and positive externalities, and to apply theorems and results intended for rent-seeking games to other games, and vice versa. We conclude with several examples that highlight the practical utility of our results.     

Optimal production of transplant care services

Most organ transplants are from dead donors. National transplant organizations exhibit considerable differences in terms of their donor population rates. Spain's organization is by far the most efficient in this respect. We argue that much of the productivity advantage of Spain's transplant organization proceeds from an efficient organization of the production chain, from organ procurement to transplantation. Transplants from dead donors are analogous to a common resource for the transplant community. Their circulation through the national transplant organization creates public good externalities between the care units in charge of organ retrieval and those in charge of transplantation. A socially efficient production of transplant care services obtains through an optimal control, by the national transplant agency, of both the circulation and the production of transplants. In particular, transplant shortage makes the rotten kid theorem fail in this context. The analysis also produces a natural measure of public good externalities, evaluated from the standpoint of care units.     

Group efforts when performance is determined by the “best shot”

We investigate the private provision of a public good whose level is determined by the maximum effort made by a group member. Costs of effort are either commonly known or privately known. For symmetric perfect-information games, any number of players may be active and we characterize the unique (mixed-strategy) equilibrium in which active contributors use the same strategy. Increasing the number of active players leads to stochastically lower individual efforts and level of the public good. When information is private, the symmetric equilibrium is in pure strategies. Increasing the number of players yields a pointwise reduction in the equilibrium contribution strategy but an increase in equilibrium payoffs. Comparative statics with respect to costs and levels of risk aversion are derived. Finally, whether information is public or private, equilibria are inefficient—we provide mechanisms that improve efficiency.     

Stable Coalition Structures with Externalities

This paper argues that the sign of external effects of coalition formation provides a useful organizing principle in examining economic coalitions. In many interesting economic games, coalition formation creates eithernegativeexternalities orpositiveexternalities for nonmembers. Examples of negative externalities are research coalitions and customs unions. Examples of positive externalities include output cartels and public goods coalitions. I characterize and compare stable coalition structures under the following three rules of coalition formation: the Open Membership game of Yi and Shin (1995), the Coalition Unanimity game of Bloch (1996), and the Equilibrium Binding Agreements of Ray and Vohra (1994).Journal of Economic LiteratureClassification Numbers: C72, C71.     

Digit ratios,the menstrual cycle and social preferences

We examine whether social preferences are partially determined by biological factors. We do this by investigating whether digit ratios (2D:4D) and menstrual cycle information are correlated with choices in ultimatum, trust, public good and dictator games. Digit ratios are thought to be a proxy for prenatal testosterone and oestrogen exposure and the menstrual cycle is a proxy for contemporary variations in a range of hormones. We find that digit ratios predict giving in all games. In our preferred specification, giving in the trust and public good games as well as reciprocity in the trust and ultimatum games vary significantly over the menstrual cycle. We discuss possible mechanisms behind these effects and conclude that biological factors play an important role in shaping social preferences.     

Coalitions, agreements and efficiency

If agents negotiate openly and form coalitions, can they reach efficient agreements? We address this issue within a class of coalition formation games with externalities where agents’ preferences depend solely on the coalition structure they are associated with. We derive Ray and Vohra's [Equilibrium binding agreements, J. Econ. Theory 73 (1997) 30-78] notion of equilibrium binding agreements using von Neumann and Morgenstern [Theory of Games and Economic Behavior, Princeton University Press, Princeton, 1944] abstract stable set and then extend it to allow for arbitrary coalitional deviations (as opposed to nested deviations assumed originally). We show that, while the extended notion facilitates the attainment of efficient agreements, inefficient agreements can nevertheless arise, even if utility transfers are possible.     

Efficient bidding with externalities

We implement a family of efficient proposals to share benefits generated in environments with externalities. These proposals extend the Shapley value to games with externalities and are parametrized through the method by which the externalities are averaged. We construct two slightly different mechanisms: one for environments with negative externalities and the other for positive externalities. We show that the subgame perfect equilibrium outcomes of these mechanisms coincide with the sharing proposals.     

Insurance,self-protection,and the economics of terrorism

This paper investigates the rationale for public intervention in the terrorism insurance market. It argues that government subsidies for terror insurance have the effect of discouraging self-protection and limiting the negative externalities associated with self-protection. Cautious self-protective behavior by a target can hurt public goods like national prestige if it is seen as “giving in” to the terrorists, and may increase the loss probabilities faced by others by encouraging terrorists to substitute toward more vulnerable targets. We argue that these externalities in protection are essential for normative analysis of government intervention in insurance markets and may also explain why availability problems in this market have engendered much stronger government responses than similar problems in other catastrophe insurance markets.     

Endogenous Move Structure and Voluntary Provision of Public Goods: Theory and Experiment

In this paper, we examine voluntary contributions to a public good, embedding Varian's (1994) voluntary contribution game in extended games that allow players to choose the timing of their contributions. We show that predicted outcomes are sensitive to the structure of the extended game, and also to the extent to which players care about payoff inequalities. We then report a laboratory experiment based on these extended games. We find that behavior is similar in the two extended games: subjects avoid the detrimental move order of Varian's model, where a person with a high value of the public good commits to a low contribution, and instead players tend to delay contributions. These results suggest that commitment opportunities may be less damaging to public good provision than previously thought.     

Aggregate comparative statics

In aggregative games, each playerʼs payoff depends on her own actions and an aggregate of the actions of all the players. Many common games in industrial organization, political economy, public economics, and macroeconomics can be cast as aggregative games. This paper provides a general and tractable framework for comparative static results in aggregative games. We focus on two classes of games: (1) aggregative games with strategic substitutes and (2) nice aggregative games, where payoff functions are continuous and concave in own strategies. We provide simple sufficient conditions under which positive shocks to individual players increase their own actions and have monotone effects on the aggregate. The results are illustrated with applications to public good provision, contests, Cournot competition and technology choices in oligopoly.     

Correlated Nash equilibrium

We modify the epistemic conditions for Nash equilibrium only to accommodate Gilboa and Schmeidler's [I. Gilboa, D. Schmeidler, Maxmin expected utility with nonunique prior, J. Math. Econ. 18 (1989) 141-153] maxmin expected utility preferences, and identify the equilibrium concept in n-player strategic games that characterizes the modified epistemic conditions. The epistemic characterization supports the equilibrium concept as a minimal generalization of Nash equilibrium, in the sense that it deviates from Nash equilibrium only in terms of players' attitude towards ambiguity. Consequently, comparing it with Nash equilibrium constitutes a ceteris paribus study of the effects of ambiguity on how a game is played. For example, with ambiguity, (beliefs about) action choices are in general correlated.     

One-sided provision of a public good through bargaining under representative democracy

We examine a trade-off between strategic delegation and the internalization of interregional externalities through bargaining in the context of political economy. We show that in the case of one-sided provision of a public good, if the public good produced by one region generates a sufficiently significant spillover to another region, then interregional negotiation increases the total surplus of the entire economy.     

OPTIMISM AND PESSIMISM IN GAMES

This article considers the impact of ambiguity in strategic situations. It extends the existing literature on games with ambiguity‐averse players by allowing for optimistic responses to ambiguity. We use the CEU model of ambiguity with a class of capacities introduced by Jaffrray and Philippe (Mathematics of Operations Research 22 (1997), 165–85), which allows us to distinguish ambiguity from ambiguity‐attitude, and propose a new solution concept, equilibrium under ambiguity (EUA), for players who may be characterized by ambiguity‐preference. Applying EUA, we study comparative statics of changes in ambiguity‐attitude in games with strategic complements. This extends work in Eichberger and Kelsey (Journal of Economic Theory 106 (2002), 436–66) on the effects of increasing ambiguity if players are ambiguity averse.     

Voluntary contributions when the public good is not necessarily normal

We argue that there are interesting examples of privately provided public goods that do not satisfy the assumption of strict normality, and reconsider voluntary-contribution games in a more general framework. We show that, in general, (1) equalizing transfers between individuals with identical tastes can increase total supply of the public good, and (2) more of the public good can be supplied if agents move sequentially rather than simultaneously. These results are in sharp contrast to earlier conclusions derived in the literature under the assumption of strict normality.     

Kindness,confusion, or … ambiguity?

Other-regarding preferences or decision errors are the main explanations put forward to justify contributions exceeding the non-cooperative optimum in VCM games. An alternative rationale relies on ambiguity aversion. Ambiguity aversion increases the perceived marginal benefit of own contributions, which in equilibrium will exceed the Nash level. We present a series of experiments testing this hypothesis. To control for other-regarding preferences, we run a two-player game in which a human player plays with a virtual agent. Players are assigned either to a risky setting (known probabilities of opponent’s choices) or to an ambiguity setting (probabilities of opponent’s contribution are vague). Results show that ambiguity affects contributions. However, attitude to ambiguity appears to be affected by the location of the aggregate Nash optimum inside the decision space.     

On Monetary Expansion, Terms of Trade and Economic Growth*

In a recent paper Roberts (1978) has extended Ramanathan's model (1975) to a two-sector, two-currency and two-country neoclassical growth model with flexible exchange rates. Under the assumption that the consumption good is relatively capital intensive, Roberts obtains two important propositions: an increase in domestic monetary expansion will increase the domestic overall capital intensity, decrease the foreign overall capital intensity, and worsen the terms of trade for the country importing the investment good; an increase in domestic monetary expansion may increase or decrease the level of trade. In this paper, we add to and generalize these results by using a simple yet thorough comparative statics analysis without the factor intensity condition.¹It will be seen that the complexity and ambiguity of Roberts' results are substantially reduced.     

Bargaining one-dimensional social choices

We analyze bargaining over the one-dimension characteristic of a public good among n impatient players when decisions require q favorable votes, q?2. Stationary subgame perfect equilibrium strategies are characterized for all games with deterministic protocol. We provide a monotonicity condition (satisfied by all single-peak, strictly quasi-concave and concave utilities) that assures uniqueness for every q whenever player's utilities are symmetric around the peak. Without symmetry, the monotonicity condition assures uniqueness for qualified majorities, q>n/2, provided that agents are sufficiently patient and utilities satisfy an additional regularity condition. Asymptotic uniqueness is assured for qualified majorities by imposing only the monotonicity condition.