从事前效率问题到事后效率问题——不完全合同理论的几类经典模型比较

通过对不完全合同经典理论模型的组成要素的梳理和分类,本文首次将不完全合同理论的模型分为四种类型:行动事前不可缔约而事后可缔约的事前效率问题模型,行动事前和事后都不可缔约的事前和事后效率问题模型,事前部分可缔约的事前和事后效率问题模型,收益事后不可证实的事前和事后效率问题模型。这些不同的理论被纳入一个统一的框架中进行表述。传统的产权理论具有一些缺陷,而事后不可缔约的模型更适合研究权威、授权、科层等问题。相对于关于投资激励的事前效率问题,事后效率问题的来源要多得多。对事前与事后缔约性问题的探讨以及对事后效率问题的研究是丰富不完全合同理论发展的动力。     

Courts of Law and Unforeseen Contingencies

We study a contracting model with unforeseen contingencies inwhich the court is an active player. Ex ante, the contractingparties cannot include the risky unforeseen contingencies inthe contract they draw up. Ex post, the court observes whetheran unforeseen contingency occurred and decides whether to voidor uphold the contract. If the contract is voided by the court,the parties can renegotiate a new agreement ex post. There aretwo effects of a court that voids contracts. The parties' incentivesto undertake relationship-specific investment are reduced, andthe parties enjoy greater insurance against the unforeseen contingenciesthat the ex ante contract cannot account for. In this context,we fully characterize the optimal decision rule for the court.The behavior of the optimal court is determined by the trade-offbetween the need for incentives and the gains from insurancethat voiding in some circumstances offers to the agents.     

不完全契约理论:一个综述

标准的契约理论或委托-代理理论假定契约是完全的,然而现实中的契约是不完全的。契约的不完全会导致事前的最优契约失效,当事人在面临被“敲竹杠”的风险时会做出无效率的专用性投资。经济学家们在研究如何最大程度地减少由于契约不完全所导致的效率损失时,发展了一个新兴的不完全契约理论。本文以一个基本模型为基点,围绕专用性投资效率问题,从司法干预、赔偿、治理结构、产权以及履约等多个视角,全面地介绍了不完全契约理论的产生、发展、应用以及面临的挑战和未来的前景。     

不确定性与早期劳动合同 --契约理论的一个新发展

在劳动力市场上 ,劳动者和厂商未来的生产率都具有不确定性。早期劳动合同或签约由于一方面可以保证劳动者被排除在劳动力市场之外 ,同时也保证了厂商被排除在事后职位市场的风险之外 ,因而厂商和劳动者具有签订早期劳动合同的激励。尽管早期劳动合同或签约存在成本 ,但只要事前利益超过事后无效率的损失 ,那么早期劳动合同或签约就会发生。对于那些不能获得完全市场保险的人来说 ,签约是一种帕累托最优。早期劳动合同或签约是市场失灵的一种证明 ,早期劳动合同是一种不完全合同 ,也是一种非正式合同 ,它是对契约理论的一个发展。     

Incomplete contract, bargaining and optimal divisional structure

When complete contracting is not possible, allocating control structure becomes the second-best arrangement. This paper analyzes the design of optimal divisional structure within an organization where ex post bargaining between the potential divisional managers is possible. In much the same light as Aghion and Tirole (J Political Econ 105(1):1?C29, 1997), we study the control problem in the context of search for projects. Our model shows that when the managers cannot bargain with one another, internal integration is preferred to internal separation. Where bargaining is possible, formal divisional structure defines both the ex post bargaining position of the two managers and their incentive to search ex ante. When the managers tend to arrive at a more favorable project to the principal via bargaining, the general leader of a firm may want to choose separation instead to increase the probability of bargaining, as the symmetrical incentive requires both managers to search and get informed.     

The Reasons for Enlarging Gap of E-Commerce between China and USA

E-Commerce in China and USA almost synchronously initiated. However, nowadays the differences of E-Commerce between the two countries are larger. In this paper, we try to find out what brings about the differences of E-Commerce between the two countries. We consider the contracting process of E-Commerce and analyze ex ante, ongoing and ex post transaction cost of E-Commerce contract. The conclusion is that the differences in economy and institution between China and USA result in the differences of transaction cost, which make for the differences in status quo of E-Commerce between the two countries.     

Information-constrained optima with retrading: An externality and its market-based solution

This paper studies the efficiency of competitive equilibria in environments with a moral hazard problem and unobserved states, both with retrading in ex post spot markets. The interaction between private information problems and the possibility of retrade creates an externality, unless preferences have special, restrictive properties. The externality is internalized by allowing agents to contract ex ante on market fundamentals determining the spot price or interest rate, over and above contracting on actions and outputs. Then competitive equilibria are equivalent with the appropriate notion of constrained Pareto optimality. Examples show that it is possible to have multiple market fundamentals or price-islands, created endogenously in equilibrium.     

Bargaining In International Trade Under Exchange-Rate Uncertainty

This paper examines the implications of various contracting alternatives between exporting and importing firms on the volume of international transactions. the contracts that we study are determined in a bargaining situation under exchange-rate uncertainty. First we look at contracts which entail an ex ante commitment on price and quantity of exports without the possibility of renegotiation ex post. Second, spot contracts, i.e., the price and the quantity of exports are negotiated after the exchange the rate is known. A third type of contracts consists of ex ante commitment and ex post renegotiation.     

Should we write prenuptial contracts?

A successful marriage requires for both parties to make investments in their relationship and marital assets. How such assets would be divided if and when the parties divorce is an important factor determining each party's ex ante investment incentives. Using the incomplete contracting approach, we characterize the optimal asset division rule, one that provides the parties with the best investment incentives. We then discuss the circumstances under which the spouses would agree, in equilibrium, to contract out state-imposed rules governing the allocation of marital assets upon divorce. We conclude by exploring the implications of our results in the context of various asset division rules currently discussed by policy-makers.     

A transaction cost model of contract choice: The case of petroleum exploration

The growing literature on transaction costs posits that the structures of contracts involving exchange under uncertainty are influenced by the costs incurred by the contracting parties prior to, as well as after, a contract is signed. This research investigates the contractual responses to the substantial uncertainty attending the exchange of rights to underground petroleum deposits. It develops a transaction cost model to explain the payment structure found in these contracts. The model identifies the major transaction costs associated with the payment types used in oil and gas exploration contracts, including ex ante measurement costs and ex post production inefficiencies, and explains their effect on contract structure. Testable implications concerning variations in the payment structure of petroleum exploration contracts are generated and tested using data from private oil and gas mineral rights leasing contracts in four western states. The study has direct public policy significance in that it delineates the implications of different payment structures of oil and gas leasing contracts. These implications can be used to evaluate proposals to reform federal oil and gas leasing policies. In addition, while there has been considerable analysis of federal offshore oil and gas leasing contracts, there has been a dearth of research on private onshore oil leasing practices. This study helps to fill this empirical void.     

Alternative theories of wage dispersion

We analyze labor market models where the law of one price fails—i.e., models with equilibrium wage dispersion. We begin considering ex ante heterogeneous workers, but highlight a problem with this approach: If search is costly the market shuts down. We then assume homogeneous workers but ex post heterogeneous matches. This model is robust to search costs, and delivers equilibrium wage dispersion. However, we prove that the law of two prices holds: Equilibrium implies at most two wages. We explore other models, including one combining ex ante and ex post heterogeneity which is robust and delivers more realistic wage dispersion.     

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     

EX POST VERSUS EX ANTE MEASURES OF THE USER COST OF CAPITAL

Should we use ex post or ex ante measures of user costs to calculate the contribution of capital in a growth accounting exercise? The answer, based on a simple model of temporary equilibrium, is that ex post is better in theory. In practice researchers usually calculate ex post user costs by assuming that the rate of return is equalized across assets. But this is only true if expectations are correct. In general, the ex post rate of return differs between assets, even though ex ante it is the same. I propose a hybrid method. The index of capital services is estimated using ex ante weights; the contribution of capital is the growth of this index multiplied by the ex post income share of capital. I show that this method is theoretically correct if the production function is CES. I compare the ex post, ex ante and hybrid methods using data for 31 U.K. industries from 1970 to 2000.     

Ex ante valuation of atmospheric visibility

In a world incomplete markets for environmental goods, ex ante planned expenditures rather than ex post realized outcomes explain the values which individuals attach to these goods. We use the distance function to develop restrictions from a model of ex ante consumer behaviour involving these goods. A Contigent valuation approach is then employed to estimate policy-relavant components of the ex ante economic values that recreationists attach to differing subjective probabilities of alternative atmospheric visibility levels at a wilderness location and at an urban location in Oregon. Marginal valuations of probability changes are similar at the two sites. Marginal rates of time preference for resolving uncertainities vary between 10 and 50% and are inversely related to education. Existence value averages 10% of total value, and evidence is mixed that site-specific value act as surrogates for general environmental preferences.     

Simple contracts, renegotiation under asymmetric information, and the hold-up problem

In this article it is demonstrated that voluntary bargaining over a collective decision under asymmetric information may well lead to ex post efficiency if the default decision is non-trivial. It is argued that the default decision may be interpreted as a ‘simple’ contract that the parties have written ex ante. This result is used in order to show that simple unconditional contracts which are renegotiated may allow the hold-up problem to be solved, even if the parties’ valuations are private information.     

Public versus private ownership: Quantity contracts and the allocation of investment tasks

The government wants a certain good or service to be provided. Should the required assets be publicly or privately owned or should a partnership be formed? Building on the incomplete contracting approach, we argue that the initially specified quantity of an ex ante describable basic good can have important effects on investment incentives, which has been neglected in the literature so far. We also study how the tasks of investing in quality improvements and cost reductions should be assigned. We show how the optimal contracts and governance structures depend on the exogenous parameters of the model such as the nature of the investments and the parties' bargaining powers.     

Incentive Contracts for Natura 2000 Implementation in Forest Areas

The implementation of nature conservation policy is often based on contracts between public authorities and landowners. In this article, we model incentive contracts in forest areas in the presence of adverse selection and moral hazard when the conservation outcome is uncertain ex ante but observable ex post. The results show that agents who are likely to achieve a higher level of conservation should be offered a contract where transfers depend on the final outcome, with a bonus for a high ecological level of the forest. When conservation measures are correlated with forest management, we show that the contractual measures involve distorted transfers. We analyse the payment mechanisms used in France and Denmark in the context of the Natura 2000 policy. These mechanisms result in overcompensation and under-performance since they do not take the problem of moral hazard and natural variability into account.     

Ex post participation constraint in a principal–agent model with adverse selection and moral hazard

This paper analyzes optimal contracting when an agent has private information before contracting and exerts hidden effort that stochastically affects the output. Additionally, the contract is constrained to satisfy the agentʼs ex post participation. We highlight three features of this model. First, the agent faces countervailing incentives. Second, the separation of types is never optimal. Third, the optimal constant bonus rewarding success is distorted downward below its efficient level.     

Increasing consumer well-being: risk as potential driver of happiness

This article investigates the relation between risk and individual well-being. We propose a theoretical model of happiness that makes a distinction between ex ante evaluations of happiness and ex post assessments. The main assumptions of the model are tested through three studies based on anchoring vignettes. We show that, even if, ex ante, consumers fear high risk and do not associate it to a high level of happiness, their ex post evaluation of well-being is generally higher when identical consequences result from a high-risk situation than from a low-risk situation. Control over risk-taking reinforces the gap between ex ante and ex post measures of happiness. Thus, our article provides empirical evidence about a positive relation between risk and individual well-being, suggesting that risky experiences have the potential to increase consumer well-being.     

Unequal uncertainties and uncertain inequalities: an axiomatic approach

In this paper, we provide an axiomatic characterization of social welfare functions for uncertain incomes. Our most general result is that a small number of reasonable assumptions regarding welfare orderings under uncertainty rule out pure ex ante as well as pure ex post evaluations. Any social welfare function that satisfies these axioms should lie strictly between the ex ante and the ex post evaluations of income distributions. We also provide an axiomatic characterization of the weighted average of the minimum and the maximum of ex post and ex ante evaluations.