Embodied and Disembodied Technical Change in Fisheries: An Analysis of the Sète Trawl Fishery, 1985–1999

Overfishing and excess capacity in mostfisheries around the world have generated considerableand increasing concern about their biological and economic performance ramifications. Theseproblems, in part, stem from substantialinvestment in technical improvements to boats andequipment in fishing fleets, which exacerbatesexcess fishing capacity and low returns tofishing effort and investment, given regulatoryand biological constraints. However, little attempt hasbeen made to quantify the extent or effects oftechnical change in fisheries. In this paper, we usedetailed data on innovation patterns for 19vessels in the Sète trawl fleet of southernFrance to evaluate the contributions oftechnical change to catch rates. We find thatembodied technical change enhanced productivity by approximately one percent per year between 1985 and 1999, but that external (disembodied) events counteractedthis trend, causing a net output decline ofabout three percent per year.     

A Stochastic Frontier Production Function with Flexible Risk Properties

This paper considers a stochastic frontier production function which has additive, heteroscedastic error structure. The model allows for negative or positive marginal production risks of inputs, as originally proposed by Just and Pope (1978). The technical efficiencies of individual firms in the sample are a function of the levels of the input variables in the stochastic frontier, in addition to the technical inefficiency effects. These are two features of the model which are not exhibited by the commonly used stochastic frontiers with multiplicative error structures.An empirical application is presented using cross-sectional data on Ethiopian peasant farmers. The null hypothesis of no technical inefficiencies of production among these farmers is accepted. Further, the flexible risk models do not fit the data on peasant farmers as well as the traditional stochastic frontier model with multiplicative error structure.     

商业银行利率风险计量模型及实证分析--非平移收益曲线条件下的随机免疫策略

传统的久期理论建立在收益曲线平移等严格假设条件上，因而其在实践中的有效性大大降低了。根据Markowitz（1959）等理论可推导出：资产价格的总风险包括收益的方差和全久期向量两部分；假若商业银行采取现金中性（cash neutrality）的资产交易策略，风险计量模型可转换为线性规划问题，从而可以构建基于利率风险最小化模型的随机免疫策略。也就是说，引入随机免疫的理念来替代经典的免疫理论，通过实证分析得出：无现金交易条件下的随机免疫策略能够降低利率风险。     

“Itô's Lemma” and the Bellman Equation for Poisson Processes: An Applied View

Using the Hamilton-Jacobi-Bellman equation, we derive both a Keynes-Ramsey rule and a closed form solution for an optimal consumption-investment problem with labor income. The utility function is unbounded and uncertainty stems from a Poisson process. Our results can be derived because of the proofs presented in the accompanying paper by Sennewald (2006). Additional examples are given which highlight the correct use of the Hamilton-Jacobi-Bellman equation and the change-of-variables formula (sometimes referred to as ``Itô's Lemma'') under Poisson uncertainty.     

Jointness in production and farmers' willingness to supply non-marketed ecosystem services

This paper highlights how farmers' willingness to supply non-marketed ecosystem services (ES) is influenced by whether or not the non-marketed ES are produced jointly with agricultural products. When marketed products and non-marketed ES share some production inputs the production relationships between the two may be complementary, competitive or substitutive. Using a cost minimization framework, it is shown how complementary relationships lead to costless voluntary provision of non-marketed ES (typically the case for ES that are supportive of provisioning ES for marketed farm products). It is also shown how competitive production relationships lead to provision of non-marketed ES at lower cost than when non-marketed ES are direct substitutes for farm products or are produced outside of agriculture. The paper closes by showing how the minimum willingness to accept (WTA) payment for ES that are complementary/competitive is less than or equal to the minimum WTA for the same ES produced in substitute or independent production relationships.     

The opportunity cost of duality

A dual representation of a technology, e.g., a cost function, may not contain all of the technological information, but it will contain all of the information about input vectors that would be chosen by a cost-minimizing firm. At least this much is clear for deterministic technologies. The main question addressed in this paper is whether the same can be said about stochastic technologies and their dual representations. Despite some pessimism expressed in the stochastic frontier literature on this question, we argue that there is no extra cost imposed in the stochastic case. Thus, the conclusion of this paper is: Just dual it!     

Absorbing Team Games

A team is a group of people having the same motives but possibly different available actions. A team game is a game where two teams face each other. An absorbing game is a repeated game where some of the entries are absorbing, in the sense that once they are chosen the play terminates, and all future payoffs are equal to the payoff at the stage of termination. We prove that every absorbing team game has an equilibrium payoff and that there are -equilibrium profiles with cyclic structure. Journal of Economic Literature Classification Numbers: C72, C73.     

公共支出对我国技术效率的影响分析

文章首先应用随机前沿方法,估计了我国31省市的时变随机前沿生产函数模型,结果表明提高公共支出占GDP的比例能显著地降低技术效率,而提高公共支出的组成部分占GDP的比例对技术效率有显著的促进作用,其现实意义就是优化公共支出结构对我国的技术效率有促进作用.其次,计算了我国31省市的技术效率,结果发现东部与西部之间的技术效率差距较大,而且在进一步扩大之中.再次,对TFP变化率进行了分解,分析表明:不论是从全国还是从东中西部三地区看,对技术效率影响最大的因素都是规模经济性,而技术进步和资源配置效率影响较小.最后,根据我国目前以规模经济性对TFP变化率为主要影响因素的实际情况,指出从公共收支视角来提高技术进步和资源配置效率对TFP变化率的影响,缩短东西部技术效率的差距,是一条高效率的公共支出发展之路.     

Two–step sequential sampling

Choosing the sample size in advance is a familiar problem: often, additional observations appear to be desirable. The final sample size then becomes a random variable, which has rather serious consequences.
Two such sample extension situations will be considered here. In the first situation, the observed sample variance determines whether or not to double the original sample size. In the second situation, the variances observed in two independent samples are compared; their ratio determines the number of additional observations.     

Heteroscedasticity and Non-Monotonic Efficiency Effects of a Stochastic Frontier Model

We consider a model that provides flexible parameterizations of the exogenous influences on inefficiency. In particular, we demonstrate the model's unique property of accommodating non-monotonic efficiency effect. With this non-monotonicity, production efficiency no longer increases or decreases monotonically with the exogenous influence; instead, the relationship can shifts within the sample. Our empirical example shows that variables can indeed have non-monotonic effects on efficiency. Furthermore, ignoring non-monotonicity is shown to yield an inferior estimation of the model, which sometimes results in opposite predictions concerning the data.