Self-enforced collusion through comparative cheap talk in simultaneous auctions with entry

Campbell (J Econ Theory 82:425–450, 1998) develops a self-enforced collusion mechanism in simultaneous auctions based on complete comparative cheap talk and endogenous entry, with two bidders. His result is difficult to generalize to an arbitrary number of bidders, since the entry-decision stage of the game is characterized by strategic substitutes. This paper analyzes more-than-two-bidder, symmetric-prior cases. Two results are proved: (1) as the number of objects grows large, a full comparative cheap talk equilibrium exists and it yields asymptotically fully efficient collusion; and (2) there is always a partial comparative cheap talk equilibrium. All these results are supported by intuitive equilibria at the entry-decision stage (J Econ Theory 130:205–219, 2006; Math Soc Sci 2008, forthcoming). Numerical examples suggest that full comparative cheap talk equilibria are not uncommon even with few objects.     

On price equilibrium with multi-product firms

In this paper, we provide a result that shows existence and uniqueness of Nash equilibrium in cases in which existing methods are problematic. This result is based on a theorem by Kellogg (Proc Am Math Soc 60:207–210, 1976) that provides conditions for the existence of a unique fixed point. We apply it to the simple logit discrete choice model and the CES representative consumer model, where asymmetric cost firms produce multiple vertically and horizontally differentiated products and compete in prices.     

Strategyproof sharing of submodular costs:budget balance versus efficiency

Summary. A service is produced for a set of agents. The service is binary, each agent either receives service or not, and the total cost of service is a submodular function of the set receiving service. We investigate strategyproof mechanisms that elicit individual willingness to pay, decide who is served, and then share the cost among them. If such a mechanism is budget balanced (covers cost exactly), it cannot be efficient (serve the surplus maximizing set of users) and vice-versa. We characterize the rich family of budget balanced and group strategyproof mechanisms and find that the mechanism associated with the Shapley value cost sharing formula is characterized by the property that its worst welfare loss is minimal. When we require efficiency rather than budget balance – the more common route in the literature – we find that there is a single Clarke-Groves mechanism that satisfies certain reasonable conditions: we call this the marginal cost pricing mechanism. We compare the size of the marginal cost pricing mechanism's worst budget surplus with the worst welfare loss of the Shapley value mechanism. Received: October 26, 1998; revised version: December 3, 1999     

Secure implementation in Shapley–Scarf housing markets

This paper considers the object allocation problem introduced by Shapley and Scarf (J Math Econ 1:23–37, 1974). We study secure implementation (Saijo et al. in Theor Econ 2:203–229, 2007), that is, double implementation in dominant strategy and Nash equilibria. We prove that (1) an individually rational solution is securely implementable if and only if it is the no-trade solution, (2) a neutral solution is securely implementable if and only if it is a serial dictatorship, and (3) an efficient solution is securely implementable if and only if it is a sequential dictatorship. Furthermore, we provide a complete characterization of securely implementable solutions in the two-agent case: a solution is securely implementable if and only if it is either a constant solution or a serial dictatorship.     

Unambiguous events and dynamic Choquet preferences

This paper explores the relationship between dynamic consistency and existing notions of unambiguous events for Choquet expected utility preferences. A decision maker is faced with an information structure represented by a filtration. We show that the decision maker’s preferences respect dynamic consistency on a fixed filtration if and only if the last stage of the filtration is composed of unambiguous events in the sense of Nehring (Math Social Sci 38:197–213, 1999). Adopting two axioms, conditional certainty equivalence consistency and constrained dynamic consistency to filtration measurable acts, it is shown that the decision maker respects these two axioms on a fixed filtration if and only if the last stage of the filtration is made up of unambiguous events in the sense of Zhang (Econ Theory 20:159–181, 2002).     

Sustainable markets with short sales

Market objectives can conflict with long-term goals. Behind the conflict is the impatience axiom introduced by T. Koopmans to describe choices over time. The conflict is resolved here by introducing a new concept, sustainable markets. These differ from Arrow-Debreu markets in that traders have sustainable preferences and no bounds on short sales. Sustainable preferences are sensitive to the basic needs of the present without sacrificing the needs of future generations and embody the essence of sustainable development (Chichilnisky in Soc Choice Welf 13(2):231–257, 1996a; Res Energy Econ 73(4):467–491, 1996b). Theorems 1 and 2 show that limited arbitrage is a necessary and sufficient condition describing diversity and ensuring the existence of a sustainable market equilibrium where the invisible hand delivers sustainable as well as efficient solutions (Chichilnisky in Econ Theory 95:79–108, 1995; Chichilnisky and Heal in Econ Theory 12:163–176, 1998). In sustainable markets prices have a new role: they reflect both the value of instantaneous consumption and the value of the long-run future. The latter are connected to the independence of the axiom of choice at the foundations of mathematics (Godel 1940).     

The role of ethics and product personality in the intention to purchase organic food products: a structural equation modeling approach

The aim of the present study is to examine the role of ethical dimensions and product personality in the purchasing intention of organic food products. The Prospect method (Caprara et al. in Test Psicomet Metodol 7(3–4):113–128, 2000), which integrates the Five factors model of personality (cf. Digman in Annu Rev Psychol 41(1):417–440, 1990) and the Theory of planned behavior (Ajzen in Organ Behav Hum Decis Process, 50(2):179–211, 1991) extended to an ethical dimension, was employed, by using a Structural Equation Modeling approach. Results showed that moral norms—i.e., personal beliefs regarding what is right or wrong (Parker et al. in Br J Soc Psychol, 34(2):127–137, 1995)—can be considered the main motivator of purchasing intention, and they are, in turn, affected by subjective norms and product personality traits of Naturalness and Authenticity. Marketing implications for firms operating in the organic food industry are discussed, in their intent to shift from a “niche” market to a broader diffusion of these products.     

New unit-consistent intermediate inequality indices

This paper introduces a class of intermediate inequality indices that is, at the same time, ray-invariant and unit-consistent. These measures allow us to make possible keeping some of the good properties of Krtscha’s (Models and measurement of welfare and inequality. Springer, Heidelberg, 1994) index while maintaining the “centrist” attitude no matter howmuch the income increases.By doing so, we approach the intermediate inequality concept suggested by Del Río and Ruiz-Castillo (Soc Choice Welfare 17:223–239, 2000) and generalize it in order to extend the range of income distributions that are comparable according to this ray-invariance criterion.     

On purification of measure-valued maps

This paper presents new methods to obtain purification results for continuum games, which don’t make use of the “many more players than strategies” assumption (Yannelis in Econ Theory (in press) 2007) or of Loeb spaces (Loeb and Sun in Illinois J Math 50, 747–762, 2006). The approach presented doesn’t use nonstandard analysis; it is based on standard measure theory and in particular on the super-nonatomicity notion introduced in Podczeck (J Math Econ (in press) 2007). Thanks to Erik Balder, Peter Loeb, Yeneng Sun, and Nicholas Yannelis for helpful comments.     

The extended and generalized Shapley value: Simultaneous consideration of coalitional externalities and coalitional structure

The Shapley value assigns, to each game that is adequately represented by its characteristic function, an outcome for each player. An elaboration on the Shapley value that assigns, to characteristic function games, a “partition function” outcome is broadly established and accepted, but elaborations to encompass games with externalities (represented by partition functions) are not. Here, I show that simultaneous consideration of the two elaborations (“generalization” and “extension”) obtains a unique Shapley-type value for games in partition function form. The key requirement is that the “Extended, Generalized Shapley Value” (EGSV) should be “recursive”: the EGSV of any game should be the EGSV of itself. This requirement forces us to ignore all but the payoffs to bilateral partitions. The EGSV can be conceptualized as the ex ante value of a process of successive bilateral amalgamations. Previous Shapley value extensions, if generalized, are not recursive; indeed, they iterate to the EGSV.     

International student migration to Germany

The past decades have witnessed an impressive growth of international student mobility. This article presents first empirical evidence on international student migration to Germany, one of the most important destination countries for international students worldwide. While previous research in the field has mainly used data on international trade in educational services, I use a novel approach that analyzes student mobility as a form of migration, using data on international student migrants. An augmented gravity equation is the basis for the theoretical and empirical framework. I also provide extensive sensitivity checks of the empirical results and estimates using both the usual log-linearized and a multiplicative specification of the gravity equation, following recent work by Santos Silva and Tenreyro (Rev Econ Stat 88(4): 641–658, 2006). The results provide evidence for the importance of distance—a familiar result from the empirical migration literature. Unlike for international migration on the whole, the importance of disposable income in the home country does not seem to be too big for students, and student migrant flows from politically unfree countries are significantly lower.     

Convergence under replication of rules to adjudicate conflicting claims

We study the behavior of rules for the adjudication of conflicting claims when there is a large number of claimants with small claims. We model such situations by replicating some basic problem. We show that under replication, the random arrival rule [Math. Soc. Sci. 2 (1982) 345] behaves like the proportional rule, the rule that is the most often recommended in this context. Also, under replication, the minimal overlap rule [Math. Soc. Sci. 2 (1982) 345] behaves like the constrained equal losses rule, the rule that selects a division at which all claimants experience equal losses subject to no-one receiving a negative amount.     

Market Games in Large Economies with a Finite Number of Types

We study market games derived from an exchange economy with a continuum of agents, each having one of finitely many possible types. The type of agent determines his initial endowment and utility function. It is shown that, unlike the well-known Shapley–Shubik theorem on market games (Shapley and Shubik in J Econ Theory 1:9–25, 1969), there might be a (fuzzy) game in which each of its sub-games has a non-empty core and, nevertheless, it is not a market game. It turns out that, in order to be a market game, a game needs also to be homogeneous. We also study investment games – which are fuzzy games obtained from an economy with a finite number of agents cooperating in one or more joint projects. It is argued that the usual definition of the core is inappropriate for such a model. We therefore introduce and analyze the new notion of comprehensive core. This solution concept seems to be more suitable for such a scenario. We finally refer to the notion of feasibility of an allocation in games with a large number of players. Some of the results in this paper appear in a previous draft distributed by the name “Cooperative investment games or Population games”. An anonymous referee of Economic Theory is acknowledged for his/her comments     

Bidding for surplus in network allocation problems

In this paper we study non-cooperative foundations of network allocation rules. We focus on three allocation rules: the Myerson value, the position value and the component-wise egalitarian solution. For any of these three rules we provide a characterization based on component efficiency and some balanced contribution property. Additionally, we present three mechanisms whose equilibrium payoffs are well defined and coincide with the three rules under consideration if the underlying value function is monotonic. Non-monotonic value functions are shown to deal with allocation rules applied to monotonic covers. The mechanisms are inspired by the implementation of the Shapley value by Pérez-Castrillo and Wettstein [Bidding for the surplus: a non-cooperative approach to the Shapley value, J. Econ. Theory 100 (2) (2001) 274-294].     

Moments of truncated <Emphasis Type="Italic">t</Emphasis> and <Emphasis Type="Italic">F</Emphasis> distributions

Truncated distributions commonly arise in economics and related areas, see, for example, Lee (Econ Lett 3:165–169, 1979), Lien (Econ Lett 19:243–247, 1985; Econ Lett 20:45–47, 1986), Burdett (Econ Lett 52:263–267, 1996), Sercu (Insur: Math and Econ 20:79–95, 1997), Abadir and Magdalinos (Econom Theory 18:1276–1287, 2002), and Horrace (J Econom 126:335–354, 2005). In this note, we consider the most commonly encountered truncated distributions with heavy tails: the truncated t distribution and the truncated F distribution. For each of these distributions, we derive explicit expressions for the moments and estimation procedures by the method of moments and the method of maximum likelihood. An application is illustrated to a popular data set in the econometric literature.      

Expected consumer’s surplus as an approximate welfare measure

Except for a knife-edge case of preferences, the percentage error from using the change in expected consumer’s surplus (ECS) to approximate the willingness to pay for a change in the distribution of a random price is unbounded, in contrast to Willig’s (Am Econ Rev 66:589–597; 1976) famous approximation result for nonrandom prices. If the change is smooth on the space of random variables, and either the initial price is nonrandom or state-contingent payments are possible, then the change in ECS locally approximates the willingness to pay well. Unfortunately, this smoothness fails in some important applications. I thank Hector Chade, Glenn Ellison, Peter Hammond, Manuel Santos, seminar participants at Arizona State, Stanford and Yale and participants of the Midwest Economic Theory meetings at Indiana University and the 2004 Summer Econometric Meetings for comments.     

Bargaining and the observability of contractual commitments via third parties

This paper analyzes a two-stage model of bilateral bargaining where one of the agents has the option to delegate. A first approach is to assume that the contract between the agent and his representative is perfectly observable and can be renegotiated. Commitment effects arise although renegotiation is possible. Then, perfect observability of the contract is weakened to observe it with certain probability. Commitment effects as pure-strategy equilibria exist if this probability is sufficiently close to 1, in contrast to Bagwell's [1995] findings that imperfect observability undermines commitment. Considering the realistic case of the actual agreement between two parties being private information, the commitment value as equilibrium outcome disappears since having closed a renegotiation-proof contract offers costless self-insurance against strategic misunderstandings. The author is grateful for helpful comments from Vasco Santos, participants at the International Atlantic Economic Conference, October 7–10, 1999, Montreal, Canada, an anonymous referee, and David M. Aadland.     

Characterizing the Vickrey combinatorial auction by induction

This note studies the allocation of heterogeneous commodities to agents whose private values for combinations of these commodities are monotonic by inclusion. This setting can accommodate the presence of complementarity and substitutability among the heterogeneous commodities. By using induction logic, we provide an alternative proof of Holmstrom’s (Econometrica 47:1137–1144, 1979) characterization of the Vickrey combinatorial auction as the unique efficient, strategy-proof, and individually rational allocation rule on a smoothly connected domain of value profiles. Our approach is elementary, not involving smoothness, and intuitive in the sense that familiar properties of the single-item second-price auction provide the first step in our induction on the number of auctioned items. Moreover, our method of proof can be applied to domains which may not be smoothly connected, including nonconvex ones. The authors acknowledge the helpful comments of anonymous referee. Serizawa greatly benefited from discussion with Rajat Deb.     

Bequest Values for Marine Resources: How Important for Indigenous Communities in Less-Developed Economies?

Communities owning and living on ancestral land tend to have a strong sense of stewardship over the land and its resources, which may translate into an economic value to present generations of being able to pass on ancestral lands to future generations (i.e. bequest value). This study estimates bequest values to local users of a traditional fishing ground on the Coral Coast of Fiji, using a contingent valuation approach. Using monetary as well as time-based contributions, bequest values are estimated at between FJ$1.25–1.41 (US$1.25–1.41 (US0.64–0.73) per individual per week, or FJ183.90 (US183.90 (US106.91) per household per year. This represents a significant proportion of stated average household expenditure, comparable to spending on durable household goods, and clothes and footwear. These results suggest that low-income groups may have significant bequest values, which should be accounted for in developing-economy valuation studies.     

Reduced game and converse consistency

The initiating points of the current paper are the axiomatic characterizations, in terms of consistency, of the equal allocation of nonseparable cost value (by Moulin), the Shapley value (by Hart and Mas-Colell), and the prenucleolus (by Orshan). The basic axioms are the same, but three different reduced games can be used to distinguish these three solutions. The main purpose of the paper is to illustrate that besides the definitions of reduced games are different, the axiom converse consistency also plays an important role to distinguish these three solutions.