The competitive firm and the role of information about uncertain factor prices

This paper studies the role of information about uncertain input prices for a competitive firm. The production decision has to be taken when the price of an input factor is perceived as random. However, a signal is observable in advance, conveying some information about the future factor price. Transparency is linked to the informational content of this signal. The impact of a higher level of transparency is analyzed from an ex ante perspective, i.e. before the information signal is observed. The change of factor use, production amount and cost are determined by comparing the strength of the curvatures of total and marginal product. By contrast, ex ante profit always increases, independently of the shape of the production function.     

Certainty Independence and the Separation of Utility and Beliefs

Economists often operate under an implicit assumption that the tastes of a decision maker are quite stable, while his beliefs change with the availability of new information. We show that for a general class of preferences, a separation of a key component of tastes, the utility function, from the other components of the representation is possible only if the decision maker's preferences satisfy a mild but not completely innocuous condition, called ‘certainty independence’. We also outline the axiomatic characterization of the preferences that obtain such separation, which are a subset of the biseparable preferences.     

The genericity of beliefs-determine-preferences models revisited

Barelli [P. Barelli, On the genericity of full surplus extraction in mechanism design, J. Econ. Theory 144 (2009) 1320-1332] defines beliefs-determine-preferences (BDP) models and argues that BDP models are nongeneric in a topological sense. In this note, we point out some difficulties in Barelli?s approach. Furthermore, we follow the idea of Heifetz and Neeman [A. Heifetz, Z. Neeman, On the generic (im)possibility of full surplus extraction, Econometrica 74 (2006) 213-233] to propose a more relevant notion of BDP^? model. We prove that BDP^? models are generic, which is opposite to Barelli?s conclusion.     

Blackwell's ordering and public information

We characterize a precise comparative static on welfare and the amount of public information in an economy under uncertainty. Results dating to Hirshleifer (Amer. Econom. Rev. 61 (1971) 561) have suggested that information can have negative value in such a setting, but counterexamples using competitive equilibrium outcomes have suppressed general results to this effect. We show that under the solution concept of implementable allocations, the negative relationship between more public information in the sense of Blackwell and welfare is fully general. Furthermore, Blackwell's ranking is necessary as well as sufficient to obtain our ranking, and hence ours provides an equivalent characterization of his ordering.     

Never choose the uniquely largest a characterization

Summary In this paper we characterize choice behaviour that picks the second largest element if there is a uniquely largest; otherwise, the largest elements are picked. Having defined our choice function, we offer a complete characterization of the latter in terms of pure choice function conditions. Similarities to and divergences from conventional choice theory are explained. We discuss the motivations underlying our exercise and provide several examples for the axiomatized choice behaviour.Helpful discussions with R. Deb, M. R. Johnson, P. K. Pattanaik, A. Sen, Y. Xu, and participants at a seminar on individual and social choice in Osnabrück, November 1993, are gratefully acknowledged. One of the authors wishes to thank the British Council and the University of Osnabrück for financial support. We are also grateful to the Department of Economics at Queen Mary and Westfield College, London, for its hospitality.     

The dynamics of risk-sensitive allocations

This paper describes Pareto optimal allocations when agents have risk-sensitive preferences as formulated by Hansen and Sargent (IEEE Trans. Automat. Control 40(5) (1995) 968-971). Necessary and sufficient conditions are given for the existence and stability of steady states at which Pareto weights are time-invariant. When all agents are risk-sensitive with the same power reward function there is a unique interior steady state which is stable when the power is positive and unstable when the power is negative. When there is at least one agent with time-additive preferences eventually all risk-sensitive agents have zero Pareto weights.     

On the genericity of full surplus extraction in mechanism design

Heifetz and Neeman [A. Heifetz, Z. Neeman, On the generic (im)possibility of full surplus extraction, Econometrica 74 (2006) 213-233], using convex combinations of models, showed that full surplus extraction (FSE) in mechanism design is generically impossible, contrary to the seminal work of Cremer and McLean [J. Cremer, R. McLean, Full extraction of the surplus in Bayesian and dominant strategy auctions, Econometrica 53 (1988) 345-361]. Since Cremer and McLean did not allow convex combinations of models, the two results are not comparable. We show that FSE is generically impossible when convex combinations of models are not allowed, provided that we do not hold fixed the cardinality of models.     

Subjective probabilities on “small” domains

The Savagian choice-theoretic construction of subjective probability does not apply to preferences, like those in the Ellsberg Paradox, that reflect a distinction between risk and ambiguity. We formulate two representation results—one for expected utility, the other for probabilistic sophistication—that derive subjective probabilities but only on a “small” domain of risky events. Risky events can be either specified exogenously or in terms of choice behavior; in the latter case, both the values and the domain of probability are subjective. The analysis identifies a mathematical structure—called a mosaic—that is intuitive for both exogenous and behavioral specifications of risky events. This structure is weaker than an algebra or even a λ-system.     

Differentiating ambiguity and ambiguity attitude

The objective of this paper is to show how ambiguity, and a decision maker (DM)'s response to it, can be modelled formally in the context of a general decision model. We introduce a relation derived from the DM's preferences, called “unambiguous preference”, and show that it can be represented by a set of probabilities. We provide such set with a simple differential characterization, and argue that it is a behavioral representation of the “ambiguity” that the DM may perceive. Given such revealed ambiguity, we provide a representation of ambiguity attitudes. We also characterize axiomatically a special case of our decision model, the “α-maxmin” expected utility model.     

Observable restrictions of general equilibrium models with financial markets

This paper examines whether general equilibrium models of exchange economies with incomplete financial markets impose restrictions on prices of commodities and assets given the stochastic processes of dividends and aggregate endowments. We show that the assumption of time-separable expected utility implies restriction on the cross-section of asset prices as well as on spot commodity prices. However, a relaxation of the assumption of time separability will generally destroy these restriction.     

The exact law of large numbers via Fubini extension and characterization of insurable risks

A Fubini extension is formally introduced as a probability space that extends the usual product probability space and retains the Fubini property. Simple measure-theoretic methods are applied to this framework to obtain various versions of the exact law of large numbers and their converses for a continuum of random variables or stochastic processes. A model for a large economy with individual risks is developed; and insurable risks are characterized by essential pairwise independence. The usual continuum product based on the Kolmogorov construction together with the Lebesgue measure as well as the usual finitely additive measure-theoretic framework is shown further to be not suitable for modeling individual risks. Measurable processes with essentially pairwise independent random variables that have any given variety of distributions exist in a rich product probability space that can also be constructed by extending the usual continuum product.     

Errors in self-reported earnings: The role of previous earnings volatility and individual characteristics

I report the measurement error in self-reported earnings for a developing country using a novel data set. The data set consists of two cross-sections of the Federated States of Micronesia (FSM) wage and salary sectors; additionally, a subset of the two cross-sections may be linked to create a panel. Administrative data from FSM Social Security office are matched to the FSM Census data for the wage and salary sectors. I find that the error in annual self-reported earnings is centered on zero. Additionally, I find strong evidence for mean reversion in the data suggesting non-classical measurement error. I identify the impact of prior years' earnings variability on the current reporting of earnings using administrative data on earnings histories. Prior earnings volatility strongly affects measurement error in current period. However, the effect of prior shocks diminish significantly over time—suggesting that first-differencing and fixed-effects techniques will not improve accuracy.     

Informational smallness and the scope for limiting information rents

For an incomplete-information model of public-good provision with interim participation constraints, we show that efficient outcomes can be approximated, with approximately full surplus extraction, when there are many agents and each agent is informationally small. The result holds even if agents' payoffs cannot be unambiguously inferred from their beliefs. The contrary result of Neeman [Z. Neeman, The relevance of private information in mechanism design, J. Econ. Theory 117 (2004) 55-77] rests on an implicit uniformity requirement that is incompatible with the notion that agents are informationally small because there are many other agents who have information about them.     

Strategic argumentation

I analyze a game between an uninformed decision maker and a possibly biased expert. The expert receives a set of arguments, and each argument favors one of two alternatives. He can disclose each argument credibly, but cannot prove whether he has disclosed everything. In all equilibria, the biased expert sends messages containing arguments both for and against his preferred alternative. However, the decision maker is not influenced by the unfavorable arguments revealed by the biased expert. The latter is able to convince the decision maker to choose the biased expert?s preferred alternative only if he reveals sufficiently many favorable arguments.     

Corrigendum to “Reserve price signaling” [J. Econ. Theory 135 (1) (2007) 253-268]

We find an error in [H. Cai, J. Riley, L. Ye, Reserve price signaling, J. Econ. Theory 135 (1) (2007) 253-268]. The existence of the separating signaling equilibrium is not challenged, but the related comparative statics, while valid in the case without informational externalities between bidders, do not generalize to the case with informational externalities as claimed by the authors. General results on the influence of the number of bidders are obtained in a linear specification of the informational externalities.