A simple sufficient condition for strong implementation

In an important step forward Maskin [E. Maskin, Nash equilibrium and welfare optimality, Rev. Econ. Stud. 66 (1999) 23–38] showed that two properties – monotonicity and no veto power – are together sufficient for Nash implementation. In contrast to the vast literature that followed, this characterization has two major advantages: First, it is often easy to verify, and second, it has an elegant and simple interpretation. However, there does not exist a similar condition for social choice correspondences that are implementable in strong equilibrium. All existing characterizations are either hard to verify or apply only to comprehensive preference domains. In this paper we improve the situation by giving one such condition. Moreover, using well-known examples we show that this is a practical tool.     

A procedural condition necessary and sufficient for cyclic social preference

Several variations and generalizations of the Voting Paradox show that social-preference cycles are not peculiar to majority rule. I offer a new generalization that is demonstrably as general as possible: a relaxation of majority rule is necessary for a cycle of any sort and sufficient for a dominant one—given certain background assumptions, few and familiar. In its “Latin square” proof as well as its assumptions, the sufficiency theorem directly generalizes both the Voting Paradox and Sen's Liberal Paradox.     

The factory system in the British industrial revolution: A complementarity thesis

This paper offers an explanation for the rise of the factory system in Britain during the Industrial Revolution (1770-1850) based on the concept of complementarity: Investment in machinery, process supervision, and improved quality control formed a cluster of complementary activities in which adopting any one increased the marginal return to also adopting the others. Further, factory owners introduced process supervision not only to increase work effort, but also to balance worker incentives among production, quality control, and asset maintenance tasks. To test this hypothesis, I have constructed a new data set from firm studies and archival records. Measures of firms’ adoption of the activities are positively correlated in the cross-section of firms, providing evidence in favor of the complementarity hypothesis.     

Rates of information aggregation in common value auctions

We study the rates at which transaction prices aggregate information in common value auctions under the different information structures in Wilson (Rev. Econ. Stud. 44 (1977) 511) and Pesendorfer and Swinkels (Econometrica 65 (1997) 1247). We consider uniform-price auctions in which k identical objects of unknown value are auctioned to n bidders, where both n and k are allowed to diverge to infinity, and k/n converges to a number in [0,1). The Wilson assumptions lead to information aggregation at a rate proportional to , but the price aggregates information at a rate proportional to in the PS setting. We also consider English auctions, and investigate whether the extra information revealed in equilibrium improves convergence rates in these auctions.     

Zero-sum condition: A necessary and sufficient condition for a transitive voting system

A simple and quick way to ascertain whether or not any given majority voting system can always produce a transitive social preference orderings without imposing any restriction on the distribution of diverse individual preference orderings is to examine whether all individual voting (preference) vectors satisfy the Addition Rule or not. This conclusion was obtained by first reformulating the voting mechanism into that of a linear mapping from T^m defined by q = Σp_i. It was found that the subset P of T that can accommodate all possible individual preference ordering profiles and such that every sum vector q = Σ p_i of its member vectors p_i is contained in T can be expressed as P = {p: p∈ T, s(p) = 0}. It was also pointed out that this is equivalent to the requirement that all individual preference (voting) functions must satisfy the Addition Rule. Finally, Borda's Rule and Saposnik's Contributive Rule were shown to be examples of transitive voting rules which satisfy these necessary and sufficient conditions.     

Social norms and the fertility transition

This paper provides a norm-based explanation for two features of the fertility transition that have been observed in many different settings: the slow response to external interventions and the wide variation in the response to the same intervention. Most societies have traditionally put norms into place to regulate fertility. When the economic environment changes, individuals gradually learn through their social interactions about the new reproductive equilibrium that will emerge in their community. This characterization of the fertility transition as a process of changing social norms is applied to rural Bangladesh, where norms are organized at the level of the religious group and interactions rarely cross religious boundaries. Consistent with the view that changing social norms are driving changes in reproductive behavior in these communities, we find that the individual's contraception decision responds strongly to changes in contraceptive prevalence in her own religious group within the village whereas cross-religion effects are entirely absent. Local changes in reproductive behavior occur independently across religious groups despite the fact that all individuals in the village have access to the same family planning inputs.     

Preferences and normal goods: A sufficient condition

This note contains a sufficient condition for all goods to be normal, in the case of differentiable individual demand. This condition appears as a relationship between the first and second partial derivatives of the utility function. But it is shown that this condition is independant of the utility function chosen and, then, is a characteristic of the preference order.     

A necessary and sufficient condition for non-emptiness of the core of a non-transferable utility game

It is well-known that a transferable utility game has a non-empty core if and only if it is balanced. In the class of non-transferable utility games balancedness or the more general π-balancedness due to Billera (SIAM J. Appl. Math. 18 (1970) 567) is a sufficient, but not a necessary condition for the core to be non-empty. This paper gives a natural extension of the π-balancedness condition that is both necessary and sufficient for non-emptiness of the core.     

The social value of public information with convex costs of information acquisition

In a beauty contest framework, welfare can decrease with public information if the precision of private information is exogenous, whereas welfare necessarily increases with public information if the precision is endogenous with linear costs of information acquisition. The purpose of this paper is to reconcile these results by considering nonlinear costs of information acquisition. The main result of this paper is a necessary and sufficient condition for welfare to increase with public information. Using it, we show that costs of information acquisition are linear if and only if welfare necessarily increases with public information. Thus, welfare can decrease with public information for any strictly convex costs. This is because convex costs mitigate the so-called crowding-out effect of public information on private information, thereby making the social value of public information with endogenous precision closer to that with exogenous precision.     

A necessary and sufficient condition for the equality of the expansion rates in the von Neumann growth model

We derive a necessary and sufficient condition for the equality of the maximal physical and the minimal economic expansion rate in a linear von Neumann model. It is a generalization of Gale's sufficient condition which postulates the absence of independent subsets of commodities. We argue that the von Neumann model is of little economic interest if this condition is not fulfilled, since then only free goods are produced and only some or all of those goods which are not produced at all have positive prices.     

A characterization of the Shapley value in queueing problems

A set of agents stand to receive a service. No two agents can be served simultaneously. A queue has to be organized, and agents having to wait should receive monetary compensations. We characterize the rule assigning positions in the queue and compensations corresponding to the payoffs recommended by the Shapley value of the associated cooperative game. We use a property of independence with respect to increase in some agents’ impatience, and an equal responsibility property.     

Subgame perfect implementation: A necessary and almost sufficient condition

We present a necessary and almost sufficient condition for subgame perfect implementation of social choice correspondences. In societies with at least three individuals, any social choice correspondence which satisfies no veto power and our necessary Condition α is subgame perfect implementable. Thus Condition α is analogous to monotonicity which, by Maskin's celebrated characterization, is necessary and, in a similar way, almost sufficient for Nash implementation.     

A necessary and sufficient condition for the dominance of an improved family of estimators in linear regression models

This article presents a necessary and sufficient condition for the dominance, with respect to the risk under a general quadratic loss function, of the double k-class estimators (characterized by non-stochastic scalars) over the least squares estimator of coefficients in linear regression models.     

A new necessary condition for implementation in iteratively undominated strategies

We uncover a new necessary condition for implementation in iteratively undominated strategies by mechanisms that satisfy the “best element property” where for each agent, there exists a strategy profile that gives him the highest payoff in the mechanism. This class includes finite and regular mechanisms. We conclude that either the quasilinearity-like assumptions of available sufficiency results cannot be completely dispensed with or some mechanisms that do not satisfy the best element property must be employed. We term the condition “restricted deception-proofness.” It requires that, in environments with identical preferences, the social choice function be immune to all deceptions, making it then stronger than incentive compatibility. In some environments the conditions for (exact or approximate) implementation by mechanisms satisfying the best element property are more restrictive than previously thought.     

Another Look at the Radner-Stiglitz Nonconcavity in the Value of Information

This paper revisits the well-known result of R. Radner and J. Stiglitz (1984, in “Bayesian Models of Economic Theory,” Elsevier, Amsterdam) which shows that, under certain conditions, the value of information exhibits increasing marginal returns over some range. Their result assumes that both the number of states and the number of signal realizations are finite, assumptions which preclude most analyses of optimal information acquisition. We provide sufficient conditions that yield this nonconcavity in the value of information in a general framework; the role that these conditions play is clarified and illustrated with several examples. We also discuss the robustness of the nonconcavity result, and the difficulties involved in getting the value of information to be globally concave. Journal of Economic Literature Classification Number: D83.     

The value of information in a principal-agent model with moral hazard: The ex post contracting case

In a principal-agent model with moral hazard, a signal about the principal?s technology — the stochastic mapping from the agent?s action to the outcome — is observed before the contract is offered. The signal is either uninformative (null information), informative and observed only by the principal (private information), or also observed by the agent (public information). We show that, from an ex ante standpoint (before the signal is observed): (i) the agent prefers private to both null and public information; (ii) the principal sometimes prefers null to both private and public information; and (iii) when the principal prefers public to null information, she prefers public to private information, whereas the agent prefers private to public information. In this last situation, we also show that (iv) for any separating equilibrium with private information, there exists a contract with public information that both strictly prefer.     

The value of public information in a Cournot duopoly

We derive alternative sufficient conditions for the value of public information to be either positive or negative in a Cournot duopoly where firms technology exhibits constant returns to scale.     

A two-person game of information transmission

We consider a statistical decision problem faced by a two player organization whose members may not agree on outcome evaluations and prior probabilities. One player is specialized in gathering information and transmitting it to the other, who takes the decision. This process is modeled as a game. Qualitative properties of the equilibria are analyzed. The impact of improving the quality of available information on the equilibrium welfares of the two individuals is studied. Better information generally may not improve welfare. We give conditions under which it will.     

A unified treatment of finite and infinite economies: limited arbitrage is necessary and sufficient for the existence of equilibrium and the core

Summary. A single condition, limited arbitrage, is shown to be necessary and sufficient for the existence of a competitive equilibrium and the core in economies with any number of markets, finite or infinite, with or without short sales. This extends earlier results of Chichilnisky [8] for finite economies. This unification of finite and infinite economies is achieved by proving that in Hilbert spaces limited arbitrage is necessary and sufficient for the compactness of the Pareto frontier. Limited arbitrage has also been shown to be necessary and sufficient for a resolution of the social choice paradox [9], [10], [12], [13], [14]. Received: August 4, 1995; revised version: April 11, 1997     

A note on the value of public information in monopoly

The paper shows that in the standard model of monopoly with asymmetric information and second-degree price discrimination, the monopolist prefers to reveal public information under a form of stochastic dependence that is weaker than the affiliation of private values, private signals, and public signals.