Reducing Inefficiency in Public Good Provision Through Linking

We characterize the optimal mechanism for the provision of n public goods in an economy with m agents, binary valuations. The mechanism “links” the n problems together because decisions and transfers are based on the whole vector of valuations of the agents. In particular, the decision on whether or not to provide a public good depends not only on the valuations of the agents for that good but, in some cases, also on the valuations for the other goods reported by the low‐valuation agents. For the two‐agent case, we show that the mechanism is asymptotically efficient and we provide an example that compares its relative efficiency with optimal separate provision and with another asymptotically efficient mechanism in the literature.     

Public goods in networks

This paper considers incentives to provide goods that are non-excludable along social or geographic links. We find, first, that networks can lead to specialization in public good provision. In every social network there is an equilibrium where some individuals contribute and others free ride. In many networks, this extreme is the only outcome. Second, specialization can benefit society as a whole. This outcome arises when contributors are linked, collectively, to many agents. Finally, a new link increases access to public goods, but reduces individual incentives to contribute. Hence, overall welfare can be higher when there are holes in a network.     

A Case for Bundling Public Goods Contributions

We extend the model of voluntary contributions to multiple public goods by allowing for bundling of the public goods. Specifically, we study the case where agents contribute into a common pool which is then allocated toward the financing of two pure public goods. We explore the welfare implications of allowing for such bundling vis‐à‐vis a separate contributions scheme. We show that for high income inequality or for identical preferences among agents bundling leads to higher joint welfare. Interestingly, a welfare improvement can in some cases occur despite a decrease in total contributions. On the contrary, when agents are heterogenous, for low income inequality bundling can lead to lower total contributions and may decrease welfare compared to a separate contribution scheme. Our findings have implications for the design of charitable institutions and international aid agencies.     

Social network and private provision of public goods

Using a simple model with interdependent utilities, we study how social networks influence individual voluntary contributions to the provision of a public good. Departing from the standard model of public good provision, we assume that an agent’s utility has two terms: (a) ‘ego’-utility derived from the agent’s consumption of public and private goods, and (b) a social utility which is the sum of utility spillovers from other agents with whom the agent has social relationships. We establish conditions for the existence of a unique interior Nash equilibrium and describe the equilibrium in terms of network characteristics. We show that social network always has a positive effect on the provision of the public good. We also find that, in networks with “small world”-like modular structures, ‘bridging’ ties connecting distant parts of social network play an important role inducing an agent’s contribution to public good. Assumptions and results of the model are discussed in relation to the role of social capital in community-level development projects and to the effect of innovation networks on firms’ R&D investments.     

On the marginal cost of public funds and the optimal provision of public goods

This paper argues that, in models with heterogeneous agents, the concept of the marginal cost of public funds (MCPF) will only be useful if it is compared with an analogous concept for the benefit side. The MCPF does not assume a unique value and is not particularly illuminating in and out of itself. Also gone is the benchmark status of MCPF = 1. Turning to the provision of public goods, using a mechanism design approach, the paper constructs a two-stage proof for Kaplow's [Kaplow, L., 1996. The optimal supply of public goods and the distortionary cost of taxation. National Tax Journal 49, 513–533.] proposition concerning the “irrelevance” of labor supply and distributional concerns in public good provision. This highlights the two fundamental ingredients for his result. First, the provision of public goods per se, when it satisfies the Samuelson's rule, is only potentially Pareto-improving. Second, the actual Pareto improvement will materialize when, or if, one reforms the income tax structure. If the reform is not forthcoming, the decision on public goods provision must rely on redistributional concerns. Finally, the paper generalizes Broadway and Keen's [Boadway, R., Keen, M., 1993. Public goods, self-selection and optimal income taxation. International Economic Review 34, 463–478.] result to a model with many types of agents, many private goods and without making any assumptions regarding which self-selection constraints are or are not binding.     

Tiebout equilibria in local public good economies with spillovers

This paper analyzes the effects of spillovers on the equilibrium population distribution across jurisdictions in a local public good economy with free mobility. Spillovers are parametrized by a matrix [α_ij] where α_ij ∈ [0, 1]. When spillovers are symmetric and close to 0 or 1 (pure local public goods and pure public goods), all equilibrium jurisdiction structures are symmetric. However, any population distribution can be sustained in equilibrium for some value of the spillover parameter α. In the class of utility functions with additive externalities, we identify the unique family of utility functions for which equilibria are symmetric except for an isolated value of α. This is a class of utility functions which are linear in the public good and a power function of the private good, u(c, γ) = − A(1 − c)^β + γ. With this specification of utility, we show that an increase in α results in a more fragmented equilibrium population distribution, and that when spillovers are asymmetric and large, a jurisdiction which is more centrally located (i.e. benefits more from the public goods provided in other jurisdictions) has a larger population in equilibrium.     

Collective decisions with interdependent valuations

Many collective decision problems have in common that individuals’ desired outcomes are correlated but not identical. This paper studies collective decisions with private information about desired policies. Each agent holds private information which mainly concerns his own bliss point, but private information also affects all other agents. We concentrate on two specific mechanism, the median and mean mechanisms establish the existence of symmetric Bayesian Nash equilibria of the corresponding games and compare the performance of the mechanisms for different degrees of interdependencies. Applications of our framework include the provision of public goods and the design of decision processes in international organizations.     

Equilibrium Selection inn-Person Coordination Games

This paper investigates several approaches to equilibrium selection and the relationships between them. The class of games we study aren-person generalized coordination games with multiple Pareto rankable strict Nash equilibria. The main result is that all selection criteria select the same outcome (namely the risk dominant equilibrium) in two-person games, and that most equivalences break for games with more than two players. All criteria select the Pareto efficient equilibrium in voting games, of which pure coordination games are special cases.Journal of Economic LiteratureClassification Numbers: C70, C72, D82.     

English auctions and the Stolper-Samuelson theorem

We prove that the English auction (with bidders that need not be ex ante identical and may have interdependent valuations) has an efficient ex post equilibrium. We establish this result for environments where it has not been previously obtained. We also prove two versions of the Stolper-Samuelson theorem, one for economies with n goods and n factors, and one for non-square economies. Similar assumptions and methods underlie these seemingly unrelated results.     

Better-reply dynamics and global convergence to Nash equilibrium in aggregative games

We consider n-person games with quasi-concave payoffs that depend on a player's own action and the sum of all players' actions. We show that a discrete-time, stochastic process in which players move towards better replies—the better-reply dynamics—converges globally to a Nash equilibrium if actions are either strategic substitutes or strategic complements for all players around each Nash equilibrium that is asymptotically stable under a deterministic, adjusted best-reply dynamics. We present an example of a 2-person game with a unique equilibrium where the derivatives of the best-reply functions have different signs and the better-reply dynamics does not converge.     

The Three-Legged Race: Cooperating to Compete

In the prisoners' dilemma contest several couples play the finitely repeated prisoners' dilemma. Each time a couple cooperates, it scores a point, and a small prize is awarded to the winners. An analogue of the “folk” theorem for repeated games is obtained with subgame perfect equilibrium (SPE). Next, allowing renegotiations within each team, we study a solution concept based on renegotiation-proof equilibrium (RPE). If couples are informed about the score, no equilibrium exists. If they are not, cooperation is the unique equilibrium outcome.Journal of Economic LiteratureClassification Number: C72.     

Abreu–Matsushima Mechanisms: Experimental Evidence

Abreu–Matsushima mechanisms can be applied to a broad class of games to induce any desired outcome as the unique rationalizable outcome. We conduct experiments investigating the performance of such mechanisms in two simple coordination games. In these games one pure-strategy equilibrium is “focal”; we assess the efficacy of Abreu–Matsushima mechanisms for implementing the other pure-strategy equilibrium outcome. Abreu–Matsushima mechanisms induce some choices consistent with the desired outcome, but more choices reflect the focal outcome. Moreover, “strengthening” the mechanism has a perverse effect when the desired outcome is a Pareto-dominated risk-dominated equilibrium.Journal of Economic LiteratureClassification Number: C7.     

Equilibrium selection through incomplete information in coordination games: an experimental study

We perform an experiment on a pure coordination game with uncertainty about the payoffs. Our game is closely related to models that have been used in many macroeconomic and financial applications to solve problems of equilibrium indeterminacy. In our experiment, each subject receives a noisy signal about the true payoffs. This game (inspired by the “global” games of Carlsson and van Damme, Econometrica, 61, 989–1018, 1993) has a unique strategy profile that survives the iterative deletion of strictly dominated strategies (thus a unique Nash equilibrium). The equilibrium outcome coincides, on average, with the risk-dominant equilibrium outcome of the underlying coordination game. In the baseline game, the behavior of the subjects converges to the theoretical prediction after enough experience has been gained. The data (and the comments) suggest that this behavior can be explained by learning. To test this hypothesis, we use a different game with incomplete information, related to a complete information game where learning and prior experiments suggest a different behavior. Indeed, in the second treatment, the behavior did not converge to equilibrium within 50 periods in some of the sessions. We also run both games under complete information. The results are sufficiently similar between complete and incomplete information to suggest that risk-dominance is also an important part of the explanation.      

Long‐term care policy with lazy rotten kids

This paper studies the determination of informal long‐term care (LTC) provided by children in a scenario which is somewhere in between perfect altruism and selfish exchanges. Parents are altruistic but children are purely selfish, and neither side can make credible commitments. The model is based on Becker's “rotten kid” specification except that it explicitly accounts for the sequence of decisions. In Becker's world, with a single good efficiency is achieved. We show that when family aid is introduced the outcome is likely to be inefficient. Still, the rotten kid mechanism is at work and ensures that a positive level of LTC is provided as long as the bequest motive is operative. We identify the inefficiencies by comparing the laissez‐faire (subgame perfect) equilibrium to the first‐best allocation. We first assume that families are identical ex ante and then consider the case where dynasties differ in wealth. We study how the provision of LTC can be improved by public policies. Interestingly, crowding out of private aid by public LTC is not a problem in this setting. With an operative bequest motive, public LTC will have no impact on private aid. More amazingly still, when the bequest motive is (initially) not operative, public insurance may even enhance the provision of informal aid.     

Private money and bank runs

Abstract This paper studies bank runs in a model with private money. We show that allowing claims on demand deposits to circulate as a medium of exchange can help prevent bank runs. In our model, there exists a unique banking equilibrium where no one demands early withdrawals of real goods and agents in need of liquidity use private money to finance consumption. With private money, the unique equilibrium not only eliminates bank runs but also improves banking efficiency. The implications of our model are consistent with the evidence from the banking history of the United States.     

Unequal Contributions from Symmetric Agents in a Local Interaction Model

The main findings of the theory on the private provision of public goods under the assumptions of symmetric agents and normality are that (1) there exists a unique Nash equilibrium in which everybody contributes the same; and (2) this pattern is stable. We show that these findings no longer hold in a context characterized by local interaction. In this context, it is always possible to find preferences satisfying the assumption of normality such that the symmetric Nash equilibrium is unstable, and there exist asymmetric Nash equilibria which are locally stable.     

Cournot-Nash and Lindahl equilibria in pure public “bad” economies

Summary. Using a general equilibrium framework, this paper analyzes the equilibrium provision of a pure public bad commodity (for example pollution). Considering a finite economy with one desired private good and one pure public “bad” we explicitly introduce the concept of Lindahl equilibrium and the Lindahl prices into a pure public bad economy. Then, the Lindahl provision is analyzed and compared with the Cournot-Nash provision. The main results for economies with heterogeneous agents state that the asymptotic Lindahl allocation of the pure public bad is the null allocation. In contrast, the asymptotic Cournot-Nash provision of the public bad might approach infinity. Other results were obtained in concert with the broad analysis of the large finite economies with pure public bad commodities. Received: July 26, 2001; revised version: March 12, 2002 RID="*" ID="*" We are indebt to Nicholas Yannelis and anonymous referee for their valuable comments and suggestions. Correspondence to: B. Shitovitz     

On the folk theorem with one-dimensional payoffs and different discount factors

Proving the folk theorem in a game with three or more players usually requires imposing restrictions on the dimensionality of the stage-game payoffs. Fudenberg and Maskin (1986) assume full dimensionality of payoffs, while Abreu et al. (1994) assume the weaker NEU condition (“nonequivalent utilities”). In this note, we consider a class of n-player games where each player receives the same stage-game payoff, either zero or one. The stage-game payoffs therefore constitute a one-dimensional set, violating NEU. We show that if all players have different discount factors, then for discount factors sufficiently close to one, any strictly individually rational payoff profile can be obtained as the outcome of a subgame-perfect equilibrium with public correlation.     

A MARKET WITH A SOCIAL CONSUMPTION EXTERNALITY*

We model a spatial market in which the utility of each consumer is affected by the consumers who buy precisely the same product. The marginal contribution of consumers x's purchase on consumer y depends on |x–y|, which declines as |x–y| increases. Such modelling of preferences fits goods that signal a consumer's place in society—clothing styles, automobiles and jewellry are examples. For 2n + 1 firms we find the unique symmetric equilibrium and derive comparative statics on the optimal number of firms, the largest number of firms the market can support, and the behaviour of profits per firm as n increases.     

Payoff dominance and risk dominance in the observable delay game: a note

We examine whether the payoff dominant sequential-move (Stackelberg) outcome is realized when timing is endogenized. We adopt the observable delay game formulated by Hamilton and Slutsky [Games Econ Behav 2(1):29–46, 1990]. We find that if one sequential-move outcome is payoff dominant, either (i) the outcome both players prefer is the unique equilibrium; or (ii) two sequential-move outcomes are equilibria and the one both players prefer is risk dominant. In other words, no conflict between payoff dominance and risk dominance in the observable delay game exists, in contrast to other games such as (non pure) coordination games. We also find that even if one of two sequential-move outcomes is the unique equilibrium outcome in the observable delay game, it does not imply that the equilibrium outcome is payoff dominant to the other sequential-move outcome.