ON ADDITIVE METHODS TO SHARE JOINT COSTS*

The Shapley value theory is extended to cost functions with multiple outputs (or to production functions with multiple inputs) where each output is demanded by a different agent and the level of demand varies. Beyond the Additivity and Dummy axioms (Shapley's original axioms) we insist that the cost-share of an agent should not decrease when she increases her demand (Demand Monotonicity). This property rules out the Aumann-Shapley pricing formula, as well as any method charging average cost for homogeneous goods. We characterize the class of cost sharing methods satisfying Additivity, Dummy, Demand Monotonicity and Cross Monotonicity. The last says that when outputs i and j are cost complements (resp-cost substitutes) the cost share of i is non decreasing (resp-non increasing) in the demand of j. Two prominent methods in the class are the Shapley-Shubik method (i.e. the Shapley value of the Stand Alone cost game) and serial cost sharing (which extends to multiple goods a formula due to Moulin and Shenker). They are characterized respectively by a lower bound and by an upper bound on individual cost shares.     

Energy portfolio risk management using time-varying extreme value copula methods

This work is concerned with the statistical modeling of the dependence structure between three energy commodity markets (WTI crude oil, natural gas and heating oil) using the concept of copulas and proposes a method for estimating the Value at risk (VaR) of energy portfolio based on the combination of time series models with models of the extreme value theory before fitting a copula. Each return series is modeled by AR-(FI) GARCH univariate model. Then, we fit the GPD distribution to the tails of the residuals to model marginal residuals distributions. The extreme value copula to the iid residuals is fitted and we simulate from it to construct N portfolios and estimate VaR. As a first step, the method is applied to a two-dimensional energy portfolio. In second step, we extend method in trivariate context to measure VaR of three-dimensional energy portfolio. Dependences between residuals are modeled using a trivariate nested Gumbel copulas. Methods proposed are compared with various univariate and multivariate conventional VaR methods. The reported results demonstrate that GARCH-t, conditional EVT and FIGARCH extreme value copula methods produce acceptable estimates of risk both for standard and more extreme VaR quantiles. Generally, copula methods are less accurate compared with their predictive performances in the case of portfolio composed of exchange market indices.     

Value at risk estimation by threshold stochastic volatility model

This article proposes a threshold stochastic volatility model that generates volatility forecasts specifically designed for value at risk (VaR) estimation. The method incorporates extreme downside shocks by modelling left-tail returns separately from other returns. Left-tail returns are generated with a t-distributional process based on the historically observed conditional excess kurtosis. This specification allows VaR estimates to be generated with extreme downside impacts, yet remains empirically widely applicable. This article applies the model to daily returns of seven major stock indices over a 22-year period and compares its forecasts to those of several other forecasting methods. Based on back-testing outcomes and likelihood ratio tests, the new model provides reliable estimates and outperforms others.     

Unionized Bertrand Duopoly and Strategic Export Policy

The paper reports that an export subsidy is optimal for a unionized Bertrand duopoly. Following results published by Brander and Spencer ( Journal of International Economics , 1988, pp. 217–34), this establishes the robustness of export subsidization to the mode of competition (Cournot or Bertrand), and contrasts with nonunion results in the literature. If both firms are unionized and both governments pursue active trade policies, a subsidy remains optimal except for a narrow range of extreme substitutability between products. Nations with a lower opportunity cost of labor employ more aggressive policies in equilibrium.     

Playing for Your Own Audience: Extremism in Two‐Party Elections

This paper considers a two‐party election with a single‐dimensional policy space. We assume that each voter has a higher probability of observing the position of the party he is affiliated with than the position of the other party, an assumption that is consistent with the National Election Studies (NES) electoral data set. In equilibrium, the two parties locate away from the median, because the voters who dislike a party's platform observe its policy choice with a lower probability, and its own audience like policy choices that cater to its taste. As the asymmetry in voter information or the cost of voting increases, the parties adopt more extreme platforms, while if there are fewer extreme voters the opposite effect occurs. Making voters more symmetrically informed about the two parties' platforms increases the welfare of society, while asymmetric information acquisition by the voters is worse than no information acquisition at all.     

Distributive and Additive Costsharing of an Homogeneous Good

Individual users demand different quantities of a homogeneous good produced under variable returns. We describe the family of costsharing methods that allocate costs in proportion to demands when returns are constant, and commute with the additivity and composition of cost functions. Two simple such methods are average cost pricing and incremental costsharing. All other methods in the family combine elements of the average cost and incremental ones. Serial costsharing stands out prominently in the family, whereas the Shapley–Shubik method, and all values from the associated stand alone cooperative game, are excluded.Journal of Economic LiteratureClassification Numbers: D63, C71.     

Surplus may measure waste

When production decisions are distorted by externalities, the traditional Marshallian surplus in the input markets contains, in addition to its other components, a measure of the waste (benefit) so generated. In an extreme example of the common property type, it is shown to contain nothing but waste. That suggests another reason for caution in interpreting surpluses but also opens a new way for measuring the cost of distortions.     

Bidding for the future: signaling in auctions with an aftermarket

This paper considers auctions where bidders compete for an advantage in future strategic interactions. When bidders wish to exaggerate their private information, equilibrium bidding functions are biased upwards as bidders attempt to signal via the winning bid. Signaling is most prominent in second-price auctions where equilibrium bids are “above value.” In English and first-price auctions, signaling is less extreme since the winner incurs the cost of her signaling choice. The opportunity to signal lowers bidders’ payoffs and raises revenue. When bidders understate their private information, separating equilibria need not exist and the auction may not be efficient.     

Litigation with Symmetric Bargaining and Two-Sided Incomplete Information

We construct game-theoretic foundations for bargaining in theshadow of a trial. Plaintiff and defendant both have noisy signalsof a common-value trial judgment and make simultaneous offersto settle. If the offers cross, they settle on the average offer;otherwise, both litigants incur an additional cost and the judgmentis imposed at trial. We obtain an essentially unique Nash equilibriumand characterize its conditional trial probabilities and judgments.Some of the results are intuitive. For example, an increasein trial cost (or a decrease in the range of possible outcomes)reduces the probability of a trial. We obtain a precise nonlinearexpression for the relationship. Other results reverse findingsfrom previous literature. For example, trials are possible evenwhen the defendant's signal indicates a higher potential judgmentthan the plaintiff's signal, and when trial costs are low, middlingcases (rather than extreme cases) are more likely to settle.     

HOME MARKET EFFECTS IN THE CHAMBERLINIAN–RICARDIAN WORLD

According to conventional home market effects, free trade tends to shrink the market share for a smaller economy in differentiated manufacturing goods, and in the extreme, leads to a complete hollowing out of the industry. Departing from the original Helpman–Krugman modelling assumptions behind the home market effects, we introduce a technology advantage in terms of the difference in fixed cost and/or marginal cost between trading partners and prove that home market effects will be offset and even reverse if a small economy has better technology than another country. With a higher elasticity of substitution, the marginal cost advantage becomes more important if it is to dominate the home market effect. We also show that even with an identical country size, the intra‐industry trade addressed in the existing literature may not occur; it will occur only if the technology differential lies within a certain range that is positively affected by the level of transport cost.     

The Level of Wage Bargaining as a Firm–Union Choice

There is a trade-off between central bargaining which allows local externalities to be internalized and local bargaining which gives firms and unions the scope to determine both wages and employment simultaneously and efficiently in the sense of McDonald and Solow (1981). A model of strong unions is presented where workers are also concerned with relative wages. The trade-off is resolved by the individual firm and union on the basis of choice, using the Pareto-criterion. In the presence of a small extra contract cost under local bargaining, the main findings are: (i) central bargaining is Pareto-optimal only for extreme values of the reservation income level—a change in unemployment remuneration may cause centralization to breakdown; and (ii) centralization may also be sustained as a suboptimal Nash-equilibrium through workers' concern with relative wages—the familiar Keynesian coordination failure.     

Network topology and the efficiency of equilibrium

Different kinds of networks, such as transportation, communication, computer, and supply networks, are susceptible to similar kinds of inefficiencies. These arise when congestion externalities make the cost for each user depend on the other users' choice of routes. If each user chooses the least expensive (e.g., the fastest) route from the users' common point of origin to the common destination, the result may be Pareto inefficient in that an alternative choice of routes would reduce the costs for all users. Braess's paradox represents an extreme kind of inefficiency, in which the equilibrium costs may be reduced by raising the cost curves. As this paper shows, this paradox occurs in an (undirected) two-terminal network if and only if it is not series-parallel. More generally, Pareto inefficient equilibria occur in a network if and only if one of three simple networks is embedded in it.     

Hospital cost sharing incentives: evidence from Iceland

Hospitals’ incentives to provide health care are influenced by the degree of cost sharing between the purchaser and the provider. In most OECD countries, governments remunerate hospitals according to the activity performed. Activity is usually measured through a diagnosis related groups (DRGs) system. This study estimates the degree of cost sharing of the NordDRG classification system (the DRG version of the Nordic countries) in Iceland during 2003–2005. We first apply ordinary least square (OLS) methods to estimate the degree of cost sharing by regressing the price for each individual patient against its cost. Second, we propose an instrumental-variable approach to address the potential endogeneity of costs. The OLS estimates suggest that the degree of cost sharing is in the range 0.16–0.17 (i.e. 1$ increase in cost is associated with an increase in reimbursement by 0.16–0.17$ increase in cost is associated with an increase in reimbursement by 0.16–0.17). The instrumental-variable approach provides some evidence of endogeneity, and suggests that cost sharing is overestimated by OLS. The instrumented estimates of cost sharing are 0.11, 0.13 and 0.14 in 2003, 2004 and 2005, respectively. Regardless of the method applied, most cost sharing is associated with the retrospective features of the classification system (such as the type of treatment provided).     

当代专利制度改革的理论思潮:劫持论与反向劫持论

专利劫持论者指责专利权人基于劣质专利,选择事后主张,以诉讼相威胁,达到敲竹杠的目的;专利反向劫持论者则强调专利权人的委屈,制造业巨头们无视独立发明人或小企业主的权利主张,恣意免费使用专利技术,专利劫持和反向劫持之间似乎有着不可协调的矛盾。当前专利钓饵不断兴风作浪,将大量发明者推向专利流氓阵营。因此,既要反对专利劫持,又要避免走向反向专利劫持。专利制度改革应该综合两者观点,通过降低专利实施中交易成本、信息不对称和不确定性来维护专利制度的正当性。     

On demand responsiveness in additive cost sharing

Under partial responsibility, the ranking of cost shares should never contradict that of demands.The Solidarity axiom says that if agent i demands more, j should not pay more if k pays less. It characterizes the quasi-proportional methods, sharing cost in proportion to `rescaled' demands.Full responsibility rules out cross-subsidization for additively separable costs. Restricting solidarity to submodular cost characterizes the fixed-flow methods, containing the Shapley-Shubik and serial methods.The quasi-proportional methods meet—but most fixed-flow methods fail—Group Monotonicity: if a group of agents increase their demands, not all of them pay less. Serial cost sharing is an exception.     

THE VALUE OF HOUSEHOLD SERVICES: A SURVEY OF EMPIRICAL ESTIMATES*

This paper surveys the various estimates that have been made of the value of household services, summarizing the methods used and comparing the statistical results. It concludes that there is wide variability in the results obtained, much of which can be attributed to the differing methods. The highest values are obtained with methods based upon the opportunity cost of women in paid employment, lower with methods based upon the cost of a single housekeeper, and lowest with methods based upon pricing individual services performed. On the basis of time use studies, three factors are found to affect very strongly the value of services performed: family size, wife's market-work status, and age of youngest child. The value of total household services should include not only the wife's contribution, but also that of the husband and children, which may amount to as much as a third of the total. The increasing burden of more children, however, appears to fall mainly on the wife, with some relief from older children; the amount of time spent by husbands appears relatively invariant to number of children or work status of the wife.     

A Monte Carlo simulation estimating US hospital cost reductions associated with hypotension control in septic ICU patients

Objective: This economic analysis extends upon a recent epidemiological study to estimate the association between hypotension control and hospital costs for septic patients in US intensive care units (ICUs).

Methods: A Monte Carlo simulation decision analytic model was developed that accounted for the probability of complications—acute kidney injury and mortality—in septic ICU patients and the cost of each health outcome from the hospital perspective. Probabilities of complications were calculated based on observational data from 110?US hospitals for septic ICU patients (n?=?8,782) with various levels of hypotension exposure as measured by mean arterial pressure (MAP, units: mmHg). Costs for acute kidney injury (AKI) and mortality were derived from published literature. Each simulation calculated mean hospital cost reduction and 95% confidence intervals based on 10,000 trials.

Results: In the base-case analysis hospital costs for a hypothetical “control” cohort (MAP of 65?mmHg) were $699 less per hospitalization (95% CI: $342–$1,116) relative to a “case” cohort (MAP of 60?mmHg). In the most extreme case considered (45?mmHg vs 65?mmHg), the associated cost reduction was $4,450 (95% CI: $2,020–$7,581). More than 99% of the simulated trials resulted in cost reductions. A conservative institution-level analysis for a hypothetical hospital (which assumes no benefit for increasing MAP above 65?mmHg) estimated a cost decline of $417 for a 5?mmHg increase in MAP per ICU septic patient. These results are applicable to the US only.

Conclusions: Hypotension control (via MAP increases) for patients with sepsis in the ICU is associated with lower hospitalization cost.     

论现代企业降低成本的新途径

降低成本是企业管理追求的目标之一。随着我国市场经济和现代企业制度的初步建立 ,传统的降低成本的方法已经受到严峻的挑战。为了适应现代企业发展的要求 ,本文重点探讨了开拓降低成本的新途径和新方法。     

股票转让方式与极端收益风险——兼论新三板市场引入做市转让制度的经济后果

在极端收益风险形成机理的现有研究中,交易环节是其逻辑链条中缺失的一环;对于做市转让制度的实施效果,现有实证研究也普遍忽视了其对极端收益风险的影响.文章从交易环节入手,提出了一个解释极端收益风险形成机理的新假说,并以新三板市场引入做市转让制度为契机,实证考察了股票转让方式和极端收益风险之间的关系.研究发现:(1)与实施协议转让的股票相比,实施做市转让的股票极端收益风险显著较低,但更多的做市商并未带来显著更低的极端收益风险;(2)做市转让方式对股价暴涨风险的抑制作用在熊市中较强,对股价暴跌风险的抑制作用则在牛市中较强;(3)股票转让方式对极端收益风险的影响主要通过股票流动性路径起作用,而信息有效性路径会起作用主要是因为信息有效性和股票流动性之间的高相关性.使用处理效应模型来控制自选择偏差的影响,使用不同的极端收益风险度量指标,延长极端收益风险的计算窗口,均不改变上述实证结果.这表明,交易环节是影响极端收益风险的重要因素,做市转让方式的引入有助于降低新三板挂牌公司的极端收益风险.文章对于深入理解极端收益风险形成机理、改善新三板市场交易机制具有重要的意义.     

Social norms, information, and trust among strangers: theory and evidence

Can a social norm of trust and reciprocity emerge among strangers? We investigate this question by examining behavior in an experiment where subjects repeatedly play a two-player binary “trust” game. Players are randomly and anonymously paired with one another in each period. The main questions addressed are whether a social norm of trust and reciprocity emerges under the most extreme information restriction (anonymous community-wide enforcement) or whether trust and reciprocity require additional, individual-specific information about a player’s past history of play and whether that information must be provided freely or at some cost. In the absence of such reputational information, we find that a social norm of trust and reciprocity is difficult to sustain. The provision of reputational information on past individual decisions significantly increases trust and reciprocity, with longer histories yielding the best outcomes. Importantly, we find that making reputational information available at a small cost may also lead to a significant improvement in trust and reciprocity, despite the fact that most subjects do not choose to purchase this information.