Discrepancies between ex ante and ex post efficiency under identical subjective probabilities

Summary. Starr (1973) showed that, if people have different subjective probabilities, ex ante and ex post efficiency conflict. Conversely, under the simple preferences that he considered, the discrepancy between ex ante and ex post efficiency disappears when subjective probabilities are identical. Here I consider identical subjective probabilities, but more general preferences. First, risk attraction is admitted. Second, I dispense with the double requirement (dubbed IZU) of additive separability and state-independence of the utility of zero-date consumption, an unrealistic requirement when modeling the investment in durable goods. I find that, under IZU, and as long as ex post preferences satisfy the natural assumption of quasiconcavity (and satisfy some technical qualifications), an ex ante efficient allocation is indeed ex post efficient, but the converse is not necessarily true under risk attraction. If, on the other hand, IZU is violated, then one can have ex ante efficient allocations that are not ex post efficient, and vice-versa, even under risk aversion. Received: June 25, 1999; revised version: March 2001     

Invention under uncertainty and the threat of ex post entry

This article proposes a theoretical framework for studying the invention of new products when demand is uncertain. In this framework, under general conditions, the threat of ex post entry by a competitor can deter invention ex ante. Asymmetric market power in the ex post market exacerbates the problem. The implications of these general results are examined in a series of examples that represent important markets in the computer industry. The first is a model that shows how an operating system monopolist, by its mere presence, can deter the invention of complements, to its own detriment as well as that of society. The implications of policies such as patent protection, price regulation, and mandatory divestiture are considered. Three additional examples consider the ability of a monopolist in one market to commit to bundling an unrelated product, a pair of horizontally differentiated firms that can add a new feature to their products, and a platform leader that can be challenged in its base market by the supplier of a complementary product.     

Sequential communication with ex post participation constraints

This paper examines an informed principal-agent game with ex post participation constraints for the agent. It shows that the players do not lose by communicating in turn among themselves rather than simultaneously if and only if the principal communicates first. It then considers every Bayesian incentive compatible allocation rules that assign non-negative payoffs for one player in a bilateral asymmetric information framework. It provides necessary and sufficient conditions for sequential communication to be as efficient as simultaneous communication in implementing these allocation rules when the player with unbounded payoffs moves first.     

The public management of risk: Separating ex ante and ex post monitors

When a firm undertakes risky activities, the conflict between social and private incentives to implement safety care requires public intervention which can take the form of both monetary incentives and also ex ante or ex post monitoring, i.e., before or after an accident occurs. We delineate the optimal scope of monitoring depending on whether public monitors are benevolent or corruptible. We show that separating the ex ante and the ex post monitors increases the likelihood of ex post investigation, helps prevent capture and improves welfare.     

Ex ante and ex post long-run average cost functions

The traditional, neoclassical derivation of the long-run average cost(LAC) function is based on minimizing the cost of a given output. However, there are a number of reasons why the theoretical concept of this ex ante LAC function is likely to differ significantly from ex post cost-output observations when output is stochastic. In agriculture, the farmer's decision making criterion is assumed to be one of minimizing the cost of producing some planned output level. Average cost is then a function, inter alia, of planned output rather than realized output. It is argued that there is no operational significance in the cost-realized output relationship; in practice, the farmer's concern is with the cost-planned output relationship. This paper proposes a two-stage procedure to estimate the latter relationship. Cross-section data on UK dairy farms for 1980/1 are used to show significant differences in the ex ante and ex post relationships.     

Equally-distributed equivalent utility,ex post egalitarianism and utilitarianism

We provide an axiomatization of expected equally-distributed equivalent-utility social welfare functions in the context of Harsanyi?s impartial observer theorem. For this family of social welfare functions, we show what additional axiom is necessary and sufficient for the observer to exhibit aversion to ex post inequality. We also relate this axiomatization to our axiomatization in a companion paper of generalized utilitarian social welfare functions. Given certain richness assumptions, the only social welfare functions that belong to both families are the utilitarian.     

Ex post bidding and efficient coordination unemployment

Abstract.  We study the implementation of constrained‐efficient allocations in labour markets where a basic coordination problem leads to an equilibrium matching friction. We argue that these allocations can be achieved in a non‐cooperative equilibrium if wages are determined by ex post bidding. This holds true even in finite‐sized markets where the equilibrium‐matching process has decreasing returns to scale – where the 'Hosios rule' does not apply – both with and without heterogeneity. JEL classification: D83, J64     

Optimal algorithms and lower partial moment: ex post results

Portofolio management in the finance literature has typically used optimization algorithms to determine security allocations within a portfolio in order to obtain the best trade-off between risk and return. These algorithms, despite some improvements, are restrictive in terms of an investor's risk aversion (utility function). Since individual investors have different levels of risk aversion, this paper proposes two portfolio-optimization algorithms that can be tailored to the specific level of risk aversion of the individual investor and performs ex postevaluation tests of the algorithm performance.     

Risk aversion and incentive compatibility with ex post information asymmetry

Summary. The paper extends Diamond's (1984) analysis of financial contracting with information asymmetry ex post and endogenous “bankruptcy penalties” to allow for risk aversion of the borrower. The optimality of debt contracts, which Diamond obtained for the case of risk neutrality, is shown to be nonrobust to the introduction of risk aversion. This contrasts with the costly state verification literature, in which debt contracts are optimal for risk averse as well as risk neutral borrowers. Received: December 7, 1998; revised version: June 9, 1999     

隐名合伙应当缓行——关于公务员隐性投资的法律思考

我国现行法律没有承认隐名合伙，是具有前瞻性的，我国国情仍然不适宜设立隐名合伙制度，隐名合伙应当缓行。公务员参与隐名投资、采取隐名合伙的形式从事营利性活动是非法的。我们应当继续固守反对隐名合伙的理念，既可以克服隐名合伙的缺陷，又可以发挥有限合伙的优势；既可以为中小企业或投资者拓展融资或投资渠道，又能有效防止“官商勾结”和公务员隐性投资。     

Complexity and individual rationality in a dynamic duopoly: an experimental study

This paper reports the results of a dynamic duopoly experiment where individual decisions are matched with optimal strategies in treatments with different strategic environments. Experimental evidence confirms that the rival's behavior is a factor affecting the individual performance. At the aggregate level, we have found that the subjects' ability to identify the theoretical benchmark increases (decreases) when the rival is cooperative (aggressive). Moreover, the analysis of individual dynamic decisions shows that the subjects follow a best reply process and that learning is quicker when the rival is cooperative. This evidence points out that the intensity of competition is a determinant of the complexity of a oligopoly situation.     

隐名合伙应当缓行——关于公务员隐性投资的法律思考

我国现行法律没有承认隐名合伙,是具有前瞻性的,我国国情仍然不适宜设立隐名合伙制度,隐名合伙应当缓行.公务员参与隐名投资、采取隐名合伙的形式从事营利性活动是非法的.我们应当继续固守反对隐名合伙的理念,既可以克服隐名合伙的缺陷,又可以发挥有限合伙的优势;既可以为中小企业或投资者拓展融资或投资渠道,又能有效防止"官商勾结"和公务员隐性投资.     

Payoff equivalence between Bayesian and ex post individually rational dominant strategy mechanisms

Summary. An efficient, interim individually rational, ex post budget balanced Bayesian mechanism is shown to be payoff equivalent to an ex post individually rational and ex ante budget balanced dominant strategy mechanism. This result simplifies the search for mechanisms that implement efficient allocation rules by pointing to a class of Groves mechanisms. It eliminates the strict requirement of common knowledge of priors and can be applied to many problems of incomplete information. Received: October 22 1996; revised version: November 25, 1997     

The rationality of EIA forecasts under symmetric and asymmetric loss

The United States Energy Information Administration publishes annual forecasts of nationally aggregated energy consumption, production, prices, intensity and GDP. These government issued forecasts often serve as reference cases in the calibration of simulation and econometric models, which climate and energy policy are based on. This study tests for rationality of published EIA forecasts under symmetric and asymmetric loss. We find strong empirical evidence of asymmetric loss for oil, coal and electricity prices as well as natural gas consumption, electricity sales, GDP and energy intensity.     

Ex post vs. ex ante pricing: Optional calling plans and tapered tariffs

We study optimal nonuniform pricing in a setting where a customer's demand at the start of a billing period contains a random variable whose realization becomes known by the end of the billing period. In this context, an optional calling plan is a tariff which the consumer must select based on his/her expectations about the random variable, whereas, under a tapered tariff, the consumer's choice of usage charge is made after he/she knows the realization of the random variable. We show that for low to moderate levels of uncertainty about the random variable entering the demand function, the optional calling plan approach to nonuniform pricing yields higher expected profit than does the tapered tariff approach, given risk-neutral consumers. We illustrate this finding with a case study and argue that it is consistent with the historical evolution of tariffs in the interexchange telecommunications market.     

Interim efficient allocations under uncertainty

This paper considers an exchange economy under uncertainty with asymmetric information. Uncertainty is represented by multiple priors and posteriors of agents who have either Bewley's incomplete preferences or Gilboa-Schmeidler's maximin expected utility preferences. The main results characterize interim efficient allocations under uncertainty; that is, they provide conditions on the sets of posteriors, thus implicitly on the way how agents update the sets of priors, for non-existence of a trade which makes all agents better off at any realization of private information. For agents with the incomplete preferences, the condition is necessary and sufficient, but for agents with the maximin expected utility preferences, the condition is sufficient only. A couple of necessary conditions for the latter case are provided.     

The complexity of resource allocation and price mechanisms under bounded rationality

Summary We develop a framework for designing and evaluating the complexity of mechanisms that allocate resources in a distributed setting to agents or processors with bounded computational ability. We discuss several mechanisms and describe the construction of efficient price based mechanisms, which exploit the decentralized aspects of the problem. These price mechanisms are polynomial in the number of resources, precision of the solution, and the logarithm of the number of agents.We thank Thomas Marschak and a anonymous referee for helpful suggestions. This research was been supported by National Science Foundation Grant IRI-8902813.     

有限理性经济人假说下的财务报告列报和使用

本文在分析西蒙的有限理性经济人假说理论的基础上,论述了其经济意义:知识具有时间和主体的相对性;一般人们发现和选择的只能是满意的方案而不是最优方案;有限理性经济人在进行经济活动时,一般遵循的是程序理性穴Procedualrationality雪而非结果理性穴Rationalityofoutcome雪;无论是完全理性经济人假说,还是有限理性经济人假说,其本质都是经济人假说,经济人的行为动机一定是追求利益最大化。根据这一意义,提出了在有限理性经济人假说理论下,财务报告所列报的是根据财务报告目标要求,依据会计规则所产生的财务信息,这种财务信息必定存在“规则性失真”和信息的不完全性;此外,会计规则内容在不同时期会发生变动,以适应不同时期不同利益集团之间利益协调的改变,为此,财务报告的列报内容也会发生相应的改变。这一结论的现实意义是:人们使用财务报告时,首先,必须具备必要的经济学、会计学、管理学等相关知识;其次,对财务报告所提供的信息应允许有一定范围的“失真”;第三,对信息的不全面性和不完整性以及财务报告内容的变化要有充分的估计和思想准备。只有这样,才能正确地理解和使用财务报告。