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.     

Efficient Intra-Household Allocations and Distribution Factors: Implications and Identification

This paper provides an exhaustive characterization of testability and identifiability issues in the collective framework in the absence of price variation; it thus provides a theoretical underpinning for a number of empirical works that have been developed recently. We first provide a simple and general test of the Pareto-efficiency hypothesis, which is consistent with all possible assumptions on the private or public nature of goods, all possible consumption externalities between household members, and all types of interdependent individual preferences and domestic production technology. The test is proved to be necessary and sufficient. We then provide conditions for the identification of the sharing rule and the Engel curves of individual household members for a variety of different observational schemes.     

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.     

Household Decisions and Equilibrium Efficiency

A general equilibrium model is introduced where a household may consist of several members, each with individual preferences and/or resources. When households obey collective rationality, certain intrahousehold externalities can be fully internalized by the respective households so that competitive exchange among households is efficient. As a rule, however, such intrahousehold externalities are not fully internalized by individual household members acting in their personal interest so that competitive exchange among such individuals is only efficient in exceptional cases.     

Deviant generations, Ricardian equivalence, and growth cycles

Two equilibrium possibilities are known to obtain in a standard overlapping-generations model with dynastic preferences: either the altruistic bequest motive is operative for every generation (in which case, Ricardian equivalence obtains) or it is not, for any generation. Dynamic equilibria, where the bequest motive is occasionally operative, cannot emerge. This paper studies bequest-giving behavior and out-of-steady-state bequest and growth dynamics in a Ak model with intra- and inter-generational consumption externalities. These externalities, by their very presence, do not destroy Ricardian equivalence. They may, however, give rise to deviant generations—generations that do not leave a bequest having received an inheritance, and vice versa—and that seals the fate for Ricardian equivalence. Consumption externalities may also generate interesting indeterminacies and endogenous growth cycles that did not exist otherwise.     

A testable model of consumption with externalities

This paper presents a nonparametric model of interdependent preferences, where an individual's consumption may act as an externality on the preferences of other consumers. We assume that individual price consumption data is observed for all consumers. It is known that the general consumption model with externalities imposes few restrictions on the observed data, where the consistency requirement is Nash rationalizability. We motivate potential games as an important sub class of games where the family of concave potential games is refutable and imposes stronger restrictions on observed data. We use this framework to extend the analysis of Brown and Matzkin [D. Brown, R. Matzkin, Testable restrictions on the equilibrium manifold, Econometrica 64 (1996) 1249-1262] on refutable pure exchange economies to pure exchange economies with externalities. Finally, we discuss an application of this model to inter-household consumption data.     

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     

CONSUMPTION EXTERNALITIES, PREFERENCE CHANGES AND THE 'SAMARITAN'S DILEMMA'

This paper examines the desirability of an exogenously induced change in the preferences of individuals in an economy characterized by (i) asymmetrical, localized positive consumption externalities, (ii) private, non-market, negotiation-free transfers, and (iii) the ‘Samaritan's dilemma.’ A model is analysed in which a benefactor (individual 1) makes an unrestricted voluntary transfer to a beneficiary (individual 2) who ran use the transfer to increase 2's consumption of either a purely private good x or a good y that generates external benefits for 1. Once 1 makes a transfer to 2, 1 cannot control how 2 spends it. If 2 fails to take into account this externality, then good y is under consumed and a loss in social welfare results. When such externalities and their concomitant welfare losses arise, conventional solutions are frequently inappropriate, impractical or impossible. This power shows that exogenously inducing the adoption of new externality internalizing preferences by the benefactor and the beneficiary not only increases the benefactor's transfer and the beneficiary's consumption of good y but also produces a ‘socially superior’ state. The welfare improvement is measured in terms of a welfare criterion that is based on the initial and new preferences of each individual     

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.     

I’LL NEVER FORGET MY FIRST CIGARETTE: A REVEALED PREFERENCE ANALYSIS OF THE “HABITS AS DURABLES” MODEL*

We provide a revealed preference analysis of the “habits as durables” model. This approach avoids the need to impose a functional form on the underlying utility function. We show that our characterization is testable by means of linear programming methods, and we demonstrate its practical usefulness by means of an application to cigarette consumption using a Spanish household consumption data set. We find that the “habits as durables” model has better empirical fit in terms of predictive success compared to the “short memory habits” and life cycle models.     

Will the consumption externalities' effects in the Ramsey model please stand up?

According to the prior literature, in a Ramsey model, consumption externalities have no impact on steady state behavior, once labor supply is exogenous. In contrast, this paper argues that — in the presence of technical change — consumption externalities always affect steady state behavior, via their impact on the elasticity of marginal utility of consumption.     

Strategy-Proof Probabilistic Decision Schemes for One-Dimensional Single-Peaked Preferences

Collective decision problems are considered with a finite number of agents who have single-peaked preferences on the real line. A probabilistic decision scheme assigns a probability distribution over the real line to every profile of reported preferences. The main result of the paper is a characterization of the class of unanimous and strategy-proof probabilistic schemes with the aid of fixed probability distributions that play a role similar to that of the phantom voters in H. Moulin (Public Choice35 (1980), 437-455). Thereby, the work of Moulin (1980) is extended to the probabilistic framework. Journal of Economic Literature Classification Numbers: D71, D81.     

Collective household labor supply: nonparticipation and income taxation

In this paper, we adopt the usual assumptions of the collective approach, i.e., individualism and efficiency, to study household labor supply. The theoretical innovation is 2-fold. First, we incorporate the decision to participate in the labor market in the initial setting. Second, we abandon the assumption of linearity of the budget constraint. We show that (i) structural elements such as preferences or the outcome of the decision process can be recovered, and (ii) testable restrictions are generated from the observation of the household labor supplies. We also examine, for this model, how to simulate the incidence of fiscal reforms.     

Groups, collective decisions and markets

We consider a general equilibrium model where multi-member households make efficient collective consumption decisions and operate in a competitive market environment. Individuals have the option to leave the household and make it on their own or join another household. We study the effect of these outside options on household formation, household stability and equilibrium existence.     

Pigouvian pricing and stochastic evolutionary implementation

We study the implementation of efficient behavior in settings with externalities. A planner would like to ensure that a group of agents make socially optimal choices, but he only has limited information about the agents’ preferences, and can only distinguish individual agents through the actions they choose. We describe the agents’ behavior using a stochastic evolutionary model, assuming that their choice probabilities are given by the logit choice rule. We prove that there is a simple price scheme with the following property: regardless of the realization of preferences, a group of agents subjected to the price scheme will spend the vast majority of time in the long run behaving efficiently. The price scheme defines a game that may possess multiple equilibria, but we are able to obtain a unique and efficient selection from this set because of the stochastic nature of the agents’ choice rule. We conclude by comparing the performance of our price scheme with that of VCG mechanisms.     

Do Addicts Behave Rationally?

The theory of rational addiction assumes that addicts' behavior is fully rational. Common sense and psychological introspection suggest, however, that addictive behavior is irrational. Without knowledge of the addicts' preferences this dispute cannot be resolved. This paper reports the results of an experiment in which addictive preferences were induced. It turns out that ‘addicts’ consume systematically too much compared to the optimal consumption decision. We explain this systematic excess consumption in terms of the psychologically salient features of addictive goods.     

Subgame perfect implementation: A full characterization

Moore and Repullo [Subgame perfect implementation, Econometrica 56 (1988) 1191-1220], and Abreu and Sen [Subgame perfect implementation: a necessary and almost sufficient condition, J. Econ. Theory 50 (1990) 285-299] introduce distinct necessary and sufficient conditions for SPE implementation, when the number of players is at least three. This paper closes the gap between the conditions—a complete characterization of the SPE implementable choice rules is provided. The characterization consists of α^*, which strengthens α of Abreu-Sen by adding it a restricted veto-power condition, and the unanimity condition. Under strict preferences α^* is equal to α.     

Consumption externalities, production externalities, and efficient capital accumulation under time non-separable preferences

The effects of consumption and production externalities on economic performance under time non-separable preferences are examined both theoretically and numerically. We show that a consumption externality alone has long-run distortionary effects if and only if labor is supplied elastically. With fixed labor supply, it has only transitional distortionary effects. Production externalities always generate long-run distortions, irrespective of labor supply. The optimal tax structure to correct for the distortions is characterized. We compare the implications of this model with those obtained when the consumption externality is contemporaneous. While some of the long-run effects are robust, there are also important qualitative and quantitative differences, particularly along transitional paths.     

Do rational demand functions differ from irrational ones? Evidence from an induced budget experiment

Various studies (e.g. Becker, 1962; Ariely et al., 2003) have noted anomalies concerning the relationship between observed demand and the preferences presumed to motivate it. We re-examine these findings using experimental choice data. After separating our subjects’ choices into rational and irrational subsets based on consistency with the axioms of revealed preference, we estimate and compare demand coefficients. Mirroring Ariely et al.'s ‘coherently arbitrary’ choice, both rational and irrational demand estimates exhibit negative price and positive endowment coefficients. However, a comparison of the full set of demand coefficients indicates significant differences between the two, yielding an observable artefact of the preference hypothesis. Relaxing the goodness-of-fit of the revealed preference test (Afriat, 1987; Varian, 1994) does not alter our findings.     

Inter-temporal choices with temporal reference dependence

I develop an intertemporal choice model for rational deviators whose preferences depend not only on their actual consumption but also on comparison to their beliefs about the optimal consumption. The standard decision maker is loss averse with respect to this belief-dependent reference point. When psychologically weighted loss aversion is low, a decision maker deviates from the standard intertemporal choice behavior and over-consumption, as well as the alternative possibility of under-consumption can be rationalized. When the decision maker has time-varying degrees of loss aversion, he re-optimizes the consumption plan through adjusted beliefs as subsequent selves realize that past decision for the present period is no longer optimal. In the dynamic model, I solve for consistent intertemporal optimization rules by which a dynamic deviator should meet rational intertemporal consistency at each point in time. Finally, I demonstrate that the dynamic reference dependent model can solve a puzzling feature in lifecycle consumption data.