中国大豆产业国际竞争力分析

本文介绍了中国大豆进出口现状以及通过国际竞争力评价指标体系说明中国大豆出口的竞争优势与劣势,综合中国大豆产业所存在的问题和所具有的优势,提出在WTO的规则下,中国应采取的对策.     

Column generation with free replicability in DEA

The evaluation of efficiency scores in data envelopment analysis is based on the construction of artificial decision making units subject to some assumptions, usually requiring convexity of the production possibility set. This demands divisibility in input and output, which is not always possible. The so-called free replicability model, proposed by Henry Tulkens, permits input and output to enter in only discrete amounts. The model is of a mixed integer programming type, for which the number of variables, here corresponding to the decision making units, may be critical in order to reach an optimal solution.     

Coordinating contracts for a financially constrained supply chain

We consider a financially constrained supply chain in which a supplier (leader) sells products to a retailer (follower) who has no access to bank financing due to her low credit rating. However, the supplier can borrow from a bank and offer trade credit to the retailer to alleviate her financial constraint. Failure to pay off a bank loan or trade credit incurs a variable default cost. We analyze the centralized version of the supply chain to obtain new coordination requirements. We then examine whether revenue-sharing, buyback, and all-unit quantity discount contracts can coordinate our supply chain. We show that the all-unit quantity discount contract fails to coordinate. However, the revenue-sharing and buyback contracts can coordinate the supply chain, but only when the supply chain has a sufficient total working capital. Moreover, they cannot allocate profit flexibly unless the supplier has a large enough working capital. Finally, we design a generalized revenue-sharing contract that coordinates the supply chain with flexible profit allocation, and also show by numerical examples its superiority over the revenue-sharing and buyback contracts.     

To Leave an Area After Disaster: How Evacuees from the WTC Buildings Left the WTC Area Following the Attacks

How people leave a devastated area after a disaster is critical to understanding their ability to cope with risks they face while evacuating. Knowledge of their needs for communications about these risks is particularly crucial in planning for emergency responses. A convenience sample of 1,444 persons who survived the World Trade Center (WTC) attacks on September 11, 2001 were surveyed to ascertain their initial and ultimate destinations once they had left the buildings, how they arrived there, the role of types of obstacles they encountered, and the need for information and the seeking of other people as potential factors in influencing the process of leaving immediately. This survey was part of a larger, original survey. Results showed differences in how people traveled by mode to initial and ultimate destinations, how immediately they left the area, and factors associated with when they left. How they traveled and when they left were associated with where people lived, their tendency in times of stress to seek out other people including who they knew in the immediate area (e.g., co‐workers or friends), the physical conditions surrounding them, and the importance to some of waiting for more information. Many people indicated they did not leave immediately because they had no information about where to go or what services would be available to them. Perceptions and communications about risks they were facing were reflected in the choices they considered in how and when to leave the area. These findings have numerous ramifications for understanding and guiding personal behavior in catastrophic situations.     

Coverage probabilities of nonparametric simultaneous confidence bands for a survival function

Simultaneous confidence bands provide a useful adjunct to the popular Kaplan–Meier product limit estimator for a survival function, particularly when results are displayed graphically. They allow an assessment of the magnitude of sampling errors and provide a graphical view of a formal goodness-of-fit test. In this paper we evaluate a modified version of Nair's (1981) simultaneous confidence bands. The modification is based on a logistic transformation of the Kaplan–Meier estimator. We show that the modified bands have some important practical advantages.     

运输服务贸易统计数据的正向调整

过去三十年间,服务贸易在全球经济生活中的地位日趋重要,吸引越来越多研究者的关注。一些研究者集中分析服务业市场开放政策对母国经济及行业绩效的积极作用,另一些则借助经济模型探讨服务贸易对全球经济一体化的影响。本文则将视角放在运输服务贸易统计问题上,力图证明运输服务贸易出口普遍被低估,在进一步的经济分析之前需要首先调整相关数据以获得更为准确的分析结果。     

比较优势、最终消费与我国贸易顺差 ——兼论全球经济危机和人民币汇率对贸易顺差的冲击

 当前研究认为我国贸易顺差来源于国内实际因素,至于是何种实际因素却存在分歧。本文建立的贸易收支决定模型认为,本国供给相对上升,本国需求相对下降,本国供给相对于本国需求过剩,是我国贸易顺差形成的根本原因。根据模型还可知,全球经济危机虽然导致我国进出口大幅下降,但对我国贸易顺差的作用相对较小;人民币升值对本国相对需求影响较小,但是对本国相对供给影响较大,如果人民币大幅度升值,我国大部分劳动密集型产业则会丧失比较优势,我国贸易顺差因此而出现拐点。     

Nonparametric covariate adjustment for receiver operating characteristic curves

The accuracy of a diagnostic test is typically characterized using the receiver operating characteristic (ROC) curve. Summarizing indexes such as the area under the ROC curve (AUC) are used to compare different tests as well as to measure the difference between two populations. Often additional information is available on some of the covariates which are known to influence the accuracy of such measures. The authors propose nonparametric methods for covariate adjustment of the AUC. Models with normal errors and possibly non‐normal errors are discussed and analyzed separately. Nonparametric regression is used for estimating mean and variance functions in both scenarios. In the model that relaxes the assumption of normality, the authors propose a covariate‐adjusted Mann–Whitney estimator for AUC estimation which effectively uses available data to construct working samples at any covariate value of interest and is computationally efficient for implementation. This provides a generalization of the Mann–Whitney approach for comparing two populations by taking covariate effects into account. The authors derive asymptotic properties for the AUC estimators in both settings, including asymptotic normality, optimal strong uniform convergence rates and mean squared error (MSE) consistency. The MSE of the AUC estimators was also assessed in smaller samples by simulation. Data from an agricultural study were used to illustrate the methods of analysis. The Canadian Journal of Statistics 38:27–46; 2010 © 2009 Statistical Society of Canada     

国家间投入产出模型方法、研制与应用

 国家间投入产出模型是研究国际竞争力、产业和贸易关联,直到气候变化最重要和最有效的应用分析工具,近年来在全世界范围的应用越来越广泛。但是,尽管我国的国际和区域经济联系不断加强,国家间投入产出模型的研制和应用在国内还没有得到足够的重视和发挥应有的作用。国家信息中心参加研制了1985、1990、1995、2000和2005年亚洲国家间投入产出模型。本文对国家间投入产出模型、以及中国非竞争型投入产出模型的研制进行系统介绍,并定义和系统梳理其基本应用方法。     

进口对中国经济增长驱动作用的实证分析

文章通过理论与实证分析阐述了进口对中国经济增长的驱动作用。理论上主要从当前的国际环境及中国的国情两方面论述了适当增加进口的必要性和可行性。实证上则是利用动态分布滞后(ADL)模型对进口与GDP关系进行协整分析并通过建立误差修正模型(ECM)进一步说明进口对中国经济增长的促进作用。最后根据以上分析提出建议:中国应适当增加进口以解决当前存在的贸易问题。