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。     

On competitive balance in the group stage of the UEFA Champions League*

This article examines competitive balance in the group stage of the UEFA Champions League over the last two decades (1999/2000–2017/2018). Competitive balance is considered both before and after a competition. Have the groups been designed in such a way as to ensure similar levels of competitive balance ex ante? Have the demonstrated strengths (ex post competitive balance) of the different groups been similar over each season? What is the relationship between the competitive balance in the designed groups and that achieved in the same groups after the competition? Are the performance achieved in terms of ex post competitive balance similar to ex ante competitive balance levels? We found that, despite expectations, the groups' ex ante competitive balance was not homogeneous. Although ex ante competitive balance serves as a good predictor, on average, of ex post competitive balance, we observed significant differences at the levels of group and seasons. Therefore, it is possible to improve the design mechanism of the groups that make up the group stage of the champions so that they are composed homogeneously in terms of ex ante competitive balance.     

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.     

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.     

Water allocation,crop choice,and priority services

We analyze the problem of allocating irrigation water among heterogeneous farmers when water supply is stochastic. If farmers are risk-neutral, a spot market for water is efficient; while the oft-used uniform rationing system is inefficient, both ex ante and ex post. Indeed, we show that it leads farmers to overexpose to risk, thus making shortages more severe and more frequent in case of drought. We propose instead a regulation by priority classes extending Wilson, and we derive an efficiency result. We characterize the set of farmers that would win or lose from such a reform. We also argue that a system of priority classes may be preferred to a spot market system, because scarcity is easier to manage ex ante than ex post, and because this system facilitates the supply of insurance to risk-averse agents.     

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.     

Complexity and Renegotiation: A Foundation for Incomplete Contracts

The paper considers a hold-up model where only one of n future trading opportunities will prove to be efficient, and where ex post renegotiation of the ex ante contract cannot be prevented. As the environment becomes more complex ( n →∞), the outcome under any message-contingent long-term contract converges to that of the "incomplete contracting" model where trade is contractible ex post , but not ex ante . When trades are costly to describe, both ex ante and ex post , the incomplete contracting result is extended to a broader class of environments.     

Experiments on unemployment benefit sanctions and job search behavior

This paper presents the results of an experimental study on unemployment benefit sanctions. The experimental set-up allows us to distinguish between the effect of benefit sanctions once they are imposed (the ex post effect) and the threat of getting a benefit sanction imposed (the ex ante effect). We find that both effects matter. Moreover, the ex ante effect turns out to be substantial and bigger than the ex post effect. Benefits sanctions stimulate the outflow from unemployment.     

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.     

Risk Aversion and Personality Type

The finance literature supports an increasing role for behavioral aspects of investment decision-making. Among other factors such as demographics, personality type may influence risk tolerance as well. This paper explores the relationship between personality type dimensions of the Myers-Briggs Type Indicator (MBTI) and the moments approach to individual investor risk tolerance inherent in expected utility theory (EUT). Our study uses survey results to relate ex ante EUT tolerance for variance and skew to MBTI measures. Results indicate that personality type does explain individual ex ante EUT risk tolerance. Our results further suggest that the relationship between personality type and individual ex ante EUT risk tolerance is non-linear in form.     

The role of ex ante and ex post decisions in the valuation of life

This paper examines the use of ex ante and ex post criteria in the evaluation of projects involving the risk of death. One issue concerns the appropriate welfare function, and it is argued that this should reflect both ex post and ex ante considerations, but not in the form of restrictions on the welfare function. The second issue concerns the form of compensation. The argument in favour of ex post compensation as a means of reducing the cost of risk-bearing needs to be modified when risks involve more than a single dimension as they do in projects involving the risk of death.     

A note on budget balance under interim participation constraints: the case of independent types

We provide a simple proof of the equivalence between ex ante and ex post budget balance constraints in Bayesian mechanism design with independent types when participation decisions are made at the interim stage. The result is given an interpretation in terms of efficient allocation of risk.     

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.     

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.     

风险偏好的差异性与融资的多样性

我们认为,公众公司(public company)的企业价值不仅依赖于企业家事后的管理行动,而且依赖于企业家的事前努力。为了实现企业价值最大化,不仅需要给予投资者企业的控制权以遏止企业家的机会主义行为,而且还需要激励企业家的事前努力。也就是说,企业价值不仅受到控制权安排的影响,而且离不开一份企业家收益与企业绩效直接挂钩的激励计划。在如此一份激励计划下,投资者的风险偏好差异性不再是无关紧要的,因为一种区分投资者偏好的融资方式可以节约企业的融资成本,使企业有更多的现金流来激励企业家努力工作。本文证明了,多样性的融资方式,即适当比例的债权—股权融资,在一定的条件下是一种最优的融资机制。而且,在企业家拥有一定初始财富的假定下,我们解释了为什么存在各种各样的资本结构。     

Location decisions of a polluting firm and the time consistency of environmental policy

This paper considers location decisions of a monopolist, who faces a tax on its emissions in the home country, under ex post that is, time consistent, and ex ante, that is precommitment, environmental policies. We show that the monopolist will relocate more often under ex post optimal emission taxes. A government which cannot commit to an ex ante emission tax and sets its tax ex post after abatement effort has been chosen, is unable to affect the monopolist’s location decision, because it cannot commit to strategically reduce its tax level in the first stage. Domestic welfare is often higher under ex post emission taxes whenever the monopolist relocates under both policy regimes. Otherwise, welfare is higher under government commitment to an ex ante emission tax level. Thus, government commitment to a policy is not always welfare improving.     

Ordinary Shares and Managers

We argue that ordinary shares undermine any inherent commitment of its holders to resist renegotiating away ex post inefficiencies. Yet, in a dynamic adverse selection problem, such ex post inefficiencies are optimal from an ex ante point of view. We show that shareholders may use a manager in combination with a golden parachute (managerial severance payments) as a commitment device not to renegotiate ex post.     

EX ANTE INVESTMENT,EX POST REMEDIES,AND PRODUCT LIABILITY*

A firm can increase product safety through ex ante investment and can remedy quality problems after sales. An increase in product liability raises returns to ex ante investment through higher consumer demand, but may also negatively affect the investment incentive due to more ex post remedial activities. The trade‐off between these “output” and “substitution” effects can result in an inverted U‐shaped relationship between product liability and ex ante investment. We find that the firm prefers full liability, but consumer surplus can be higher under partial liability. We further identify conditions under which full liability or partial liability is socially optimal.     

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.     

Estimating Demand for Local Telephone Service with Asymmetric Information and Optional Calling Plans

In this paper, I study the theoretical and econometric implications of agents' uncertainty concerning their future consumption when a monopolist offers them either a unique, mandatory nonlinear tariff or a choice in advance from a menu of optional two–part tariffs. Agents' uncertainty is resolved through individual and privately known shocks to their types. In such a situation the principal may screen agents according to their ex ante or ex post type, by offering either a menu of optional tariffs or a standard nonlinear schedule. The theoretical implications of the model are used to evaluate a tariff experiment run by South Central Bell in two cities in Kentucky in 1986. The empirical approach explicitly accounts for the existence of informational asymmetries between local telephone users and the monopolist, leading to different, nested, econometric specifications under symmetric and asymmetric information. The empirical evidence suggests that there exists a significant asymmetry of information between consumers and the monopolist under both tariff regimes. All expected welfare components failed to increase with the introduction of optional tariffs for the estimated value of the parameters.