The empirical content of Cournot competition

We consider the testable implications of the Cournot model of market competition. Our approach is nonparametric in the sense that we abstain from imposing any functional specification on market demand and firm cost functions. We derive necessary and sufficient conditions for (reduced form) equilibrium market price and quantity functions to be consistent with the Cournot model. In addition, we present identification results for the corresponding inverse market demand function and the firm cost functions. Finally, we use our approach to derive testable restrictions for the models of perfect competition, collusion and conjectural variations. This identifies the conditions under which these different models are empirically distinguishable from the Cournot model. We also investigate empirical issues (measurement error and omitted variables) related to bringing our testable restrictions to data.     

The micro economics of group behavior: General characterization

We study the demand function of a group of S members facing a global budget constraint. Any vector belonging to the budget set can be consumed within the group, with no restriction on the form of individual preferences, the nature of individual consumptions or the form of the decision process beyond efficiency. Moreover, only the group aggregate behavior, summarized by its demand function, is observable. We provide necessary and (locally) sufficient restrictions that fully characterize the group's demand function, with and without distribution factors. We show that the private or public nature of consumption within the group is not testable from aggregate data on group behavior.     

On behavioral complementarity and its implications

We study the behavioral definition of complementary goods: if the price of one good increases, demand for a complementary good must decrease. We obtain its full implications for observable demand behavior (its testable implications), and for the consumer's underlying preferences. We characterize those data sets which can be generated by rational preferences exhibiting complementarities. The class of preferences that generate demand complements has Leontief and Cobb-Douglas as its as extreme members.     

Product differentiation and location decisions under demand uncertainty

We investigate Hotelling's duopoly game of location-then-price choices with quadratic transportation costs and uniformly distributed consumers under the assumption that firms are uncertain about the exact location of demand. We characterize the unique equilibrium and the socially optimal locations. Contrary to the individual-level random utility models, location uncertainty is a differentiation force. In equilibrium, increases in the variance of the uncertainty lead to greater differentiation, higher expected equilibrium prices and profits, and a greater welfare loss.     

Distance and beyond: What drives financial flows to emerging economies?

A major theme in the empirical literature is whether country-specific ‘pull’ or external ‘push’ factors drive international capital flows. In this paper we show that pull-push interactions matter: the response of international investors to country-specific developments depends on global volatility/liquidity stress conditions. We model asset-trade behaviour of investors: with limited information, strong institutional quality ‘pulls’ asset demand; mounting tensions in global markets amplify portfolio adjustments. We derive an empirically testable equation for cross-border bank flows to emerging economies (EMEs) and focus on pull-push interactions that trigger financial vulnerabilities. We find that global volatility amplifies demand for institutional quality, prior to the recent crisis, implying that EMEs with weak institutional settings are exposed to sharp capital retrenchments. In the aftermath of the crisis, the liquidity easing in advanced economies drives down concerns for EMEs' developments, boosting flows and challenging EMEs' ability to use capital controls to mitigate unbridled flows.     

An Empirical Study of Dynamic Labor Demand with Integrated Forcing Processes

In this paper, we examine a version of the Sargent (1978) and Kennan (1979) labor demand model under the assumption that the forcing processes are nonstationary. We derive a simple model of dynamic labor demand and highlight the important econometric and time-series implications of the optimization problem. The empirical results are surprisingly favorable and consistent with the underlying dynamic theory. Specifically, we find estimates that imply adjustment costs are about fourfold more important than disequilibrium costs in determining the dynamic demand for labor.     

Collective consumption and welfare

Abstract.  In this paper, we present a collective model of household demand based on Pareto‐efficiency. In addition, we suppose that (a) each household member is egoistic and consumption is purely private, (b) there is a set of distribution factors and (c) there is one exclusive good. Then we derive the testable restrictions that are implied by this theoretical setting and show how welfare comparisons at the individual level can be performed. JEL classification: D11     

Afriat's theorem for general budget sets

Afriat proved the equivalence of a variant of the strong axiom of revealed preference and the existence of a solution to a set of linear inequalities. From this solution he constructed a utility function rationalizing the choices of a competitive consumer. We extend Afriat's theorem to a class of nonlinear, nonconvex budget sets. We thereby obtain testable implications of rational behavior for a wide class of economic environments, and a constructive method to derive individual preferences from observed choices. We also show that by increasing in a regular way the number of observed choices from our class of budget sets one can fully identify the underlying preference relation.     

Optimal Liquidity Provision Through a Demand Deposit Scheme: The Jacklin Critique Revisited

We derive conditions such that optimal liquidity provisions through a demand deposit scheme can be sustainably implemented in a subgame perfect Nash equilibrium under the assumption that renegade investors have free access to ex post asset markets. As our qualitative main finding we demonstrate that such sustainability is more likely for ‘poor’ than for ‘rich’ scheme participants in terms of future income. By establishing sustainability for low future income populations, our formal analysis therefore offers an important qualification of Jacklin's (1987) influential claim that an optimal demand deposit scheme is not sustainable whenever there exists the possibility of an ex post asset market.     

Noncooperative versus cooperative R&D with endogenous spillover rates

This paper deals with a general version of a two-stage model of R&D and product market competition. We provide a thorough generalization of previous results on the comparative performance of noncooperative and cooperative R&D, dispensing in particular with ex-post firm symmetry and linear demand assumptions. We also characterize the structure of profit-maximizing R&D cartels where firms competing in a product market jointly decide R&D expenditure, as well as internal spillover, levels. We establish the firms would essentially always prefer extremal spillovers, and within the context of a standard specification, derive conditions for the optimality of minimal spillover.     

MISERY LOVES COMPANY: EQUILIBRIUM PORTFOLIOS WITH HETEROGENEOUS CONSUMPTION EXTERNALITIES*

The present article extends the Arrow–Debreu portfolio model to consumption externalities. It is assumed that each investor has a von Neumann–Morgenstern utility that is a function of her own consumption and of the average consumption in the group to which she belongs. Individual degrees of risk aversion and conformism are heterogeneous within each group and between the different groups in the economy. We show that, under some conditions on the degree of conformism in the economy, the optimal portfolio and consumption choices observed at equilibrium in each group with consumption externalities are equivalent to those that are optimal without any externality, but with an adjusted degree of risk aversion. If these conditions are not fulfilled, groups have no representative agent and the demand for pure zero‐mean lotteries may be positive, thereby showing that not all diversifiable risks are washed away at equilibrium. We characterize the relationship between the distribution of conformism in the economy to the competitive allocation of risk and to the equity premium. We provide conditions for the two‐fund separation property to hold.     

Subjective probability over a subjective decision tree

A state space has been assumed as a primitive for modeling uncertainty, which presumes that the analyst knows all the uncertainties a decision maker (DM) perceives. This is problematic because states are private information of the DM, and hence are not directly observable to the analyst. Dekel et al. [Representing preferences with a unique subjective state space, Econometrica 69 (2001) 891-934] derive, rather than assume, the subjective state space from preference over suitable choice objects.In a dynamic setting, a decision tree, that is, a pair consisting of a state space and a filtration, has been taken as a primitive. This assumption is also problematic—a decision tree should be derived rather than assumed as a primitive. We formulate a three-stage extension of the above literature in order to model a DM who anticipates subjective uncertainty to be resolved gradually over time. We identify also subjective beliefs on the subjective state space.     

On the multiplicity of monetary equilibria: Green-Zhou meets Lagos-Wright

Green and Zhou relax the assumption, made in early search-based models of monetary exchange, of indivisible money. Their paper and various extensions make much technical progress, and derive some interesting substantive results. In particular, they show there is an indeterminacy of steady-state monetary equilibria. We reconsider this result in the framework of Lagos and Wright, which is more tractable. We show that a similar multiplicity arises, and is much easier to derive and understand. We also compare the results to those in related nonmonetary models, and discuss how they depend on details, including the number of agents and the timing.     

Nonlinear pricing with self-control preferences

A basic assumption of economics is that consumers choose what they want. However, many consumers find it difficult to stop overeating, overspending, smoking, procrastinating, etc, even though they want to. In reality, consumers have temptation and it is psychologically costly to exercise self-control. To clarify the implications of the existence of temptation and self-control costs, this paper studies a firm's optimal selling strategy exploiting the behavioral features of consumers. We characterize optimal nonlinear pricing schemes for a monopoly when self-control is costly for consumers. Since consumers have a preference for commitment, the firm faces a trade-off between offering a small menu that makes the consumers’ self-control easier and offering a large menu that achieves better price discrimination. We show that the optimal menu resembles the one in the standard nonlinear pricing problem with a price ceiling, where the upper bound on prices is determined endogenously by a participation constraint. The ceiling motivates the firm to offer a relatively flat and compact price schedule, serving more consumers with low demand. The characterization also shows that the firm may earn less if consumers have temptation.     

An Afriat Theorem for the collective model of household consumption

We provide a nonparametric ‘revealed preference’ characterization of rational household behavior in terms of the collective consumption model, while accounting for general individual preferences that can be non-convex. Our main result is the Collective Afriat Theorem, which parallels the well-known Afriat Theorem for the unitary model. First, it provides a characterization of collectively rational consumption behavior in terms of collective Afriat inequalities. Next, it implies the Collective Axiom of Revealed Preference (CARP) as a testable necessary and sufficient condition for data consistency with collective rationality. Finally, the theorem has some interesting testability implications. With only a finite set of observations, the nature of consumption externalities (positive or negative) in the intra-household allocation process is non-testable. The same non-testability conclusion holds for privateness (with or without externalities) or publicness of consumption. By contrast, concavity of individual utility functions (representing convex preferences) turns out to be testable. In addition, monotonicity is testable for the model that assumes all household consumption is public.     

The economics of BitCoin price formation

This is the first article that studies BitCoin price formation by considering both the traditional determinants of currency price, e.g., market forces of supply and demand, and digital currencies specific factors, e.g., BitCoin attractiveness for investors and users. The conceptual framework is based on the Barro (1979) model, from which we derive testable hypotheses. Using daily data for five years (2009–2015) and applying time-series analytical mechanisms, we find that market forces and BitCoin attractiveness for investors and users have a significant impact on BitCoin price but with variation over time. Our estimates do not support previous findings that macro-financial developments are driving BitCoin price in the long run.     

Bundling as an optimal selling mechanism for a multiple-good monopolist

Multiple objects may be sold by posting a schedule consisting of one price for each possible bundle and permitting the buyer to select the price-bundle pair of his choice. We identify conditions that must be satisfied by any price schedule that maximizes revenue within the class of all such schedules. We then provide conditions under which a price schedule maximizes expected revenue within the class of all incentive compatible and individually rational mechanisms in the n-object case. We use these results to characterize environments, mainly distributions of valuations, where bundling is the optimal mechanism in the two and three good cases.     

Convergence of the Aumann–Davis–Maschler and Geanakoplos bargaining sets

Summary. Geanakoplos [17] defined a notion of bargaining set, and proved that his bargaining set is approximately competitive in large finite transferable utility (TU) exchange economies with smooth preferences. Shapley and Shubik [26] showed that the Aumann–Davis–Maschler bargaining set is approximately competitive in replica sequences of TU exchange economies with smooth preferences. We extend Geanakoplos result to nontransferable utility (NTU) exchange economies without smooth preferences, and we extend the Shapley and Shubik result to non-replica sequences of NTU exchange economies with smooth preferences.Received: November 11, 1996This revised version was published online in February 2005 with corrections to the cover date.     

Shooting fish in the barrel? Examining the standard test of the Lucas variability hypothesis

The LVH (Lucas variability hypothesis) says that the reaction of real output to changes in nominal demand depends negatively upon the variability of the rate of change of nominal demand. The LVH was first proposed as a testable prediction from R. E. Lucas' 1973 model of the business cycle – known as the misperceptions model. The LVH has frequently been successfully tested on cross-country data sets. We first replicate the standard test result. We then proceed to show that the test suffers from the problem that the same LVH-test result appears – qualitatively and quantitatively – even in models having the reverse causal structure, from the one assumed by Lucas. We have consequently shown that the LVH-test is developed within a framework where it is hard to miss -hence the title.     

Excess demand functions with incomplete markets—a global result

The purpose of this paper is to give a global characterization of excess demand functions in a two-period exchange economy with incomplete real asset markets. We show that continuity, homogeneity and Walras’ law characterize the aggregate excess demand functions on any compact price set which maintains the dimension of the budget set.