The Protective Impact of a Covariate on Competing Failures with an Example from a Bone Marrow Transplantation Study

Starting from an applied Bone Marrow Transplantation(BMT) study, the problem of “unexpected protectivity” in competing risks models is introduced, which occurs when one covariate shows a protective impact not expected from a medical perspective. Current explanations found in the statistical literature suggest that unexpected protectivity might be due to the lack of independence between the competing failures. Actually, in the presence of dependence, the Kaplan-Meier curves are not interpretable. Conversely, the cumulative incidence curves remain interpretable, and therefore seem to be a candidate for solving the problem. We discuss the particular nature of dependence in a competing risks framework and illustrate how this dependence may be created via a common frailty factor. A Monte Carlo experiment is set up which accounts also for the association between the observable covariates and the frailty factor. The aim of the experiment is to understand whether and how the bias showed by the estimates could be related to the omitted frailty variable. The results show that dependence alone does not cause false protectivity, and that the cumulative incidence curves suffer the same bias as the survival curves and therefore do not seem to be a solution to false protectivity. Conversely, false protectivity may occur according to the magnitude and the sign of the dependence between the frailty factor and the covariate. The paper ends with some suggestions for empirical research. This revised version was published online in July 2006 with corrections to the Cover Date.     

中国与哈萨克斯坦双边贸易与区域经济合作的比较优势与风险分析——一项基于地理区位与跨国公共品供给的实证研究

新亚欧大陆桥和中哈石油管道的开通及中哈之间签署的一系列双边和多边协定。为跨国区域经济合作创造了良好的跨国公共产品与跨国俱乐部产品供求基础；地理区位优势和跨国公共产品有效供给是国际贸易和跨国区域经济合作比较优势充分发挥的重要条件和基本前提；双边贸易和跨区域合作中既有比较优势，又面临风险。中国与哈萨克斯坦双边经贸必须充分发挥双方的优势，防止贸易摩擦、贸易不平衡性、贸易波动性、地缘政治和恐怖主义活动带来的风险。     

农业产业化的经营风险与风险控制

与独立的非产业化经营相比,农业产业化经营存在更多、更大的潜在风险.这是由农业产业化经营本身的组织制度安排、契约关系、要素规模、技术水平和对外部环境的依赖等特点决定的.农业产业化经营的风险类型主要包括自然风险、市场风险、资产风险、技术风险和契约风险等.根据农业产业化经营的风险特点及其表现形式,结合农业产业化实践,吸取国外农业风险管理的经验和教训,农业产业化经营风险管理应该是政府、市场、企业、农民自助的多元复合结构管理模式.     

Evaluating the Efficacy of a Mental Models Approach for Improving Occupational Chemical Risk Protection

Chemical risk protection in the workplace relies partly on informing workers about possible risks using material safety data sheets (MSDS). This article reports on phase 2 of a project (phase 1 reported in Cox et al.), which employed a mental models approach to improve on data sheets as communicative interventions for perchloroethylene in dry cleaning and rosin-based solder flux in the electronics industry within small businesses in the United Kingdom (small enterprises (SEs) < 25 employees in the workplace). It focuses on the efficacy of a multimethod evaluation strategy to assess (1) the capacity of a mental models approach to yield contextually relevant data for intervention design and (2) the effectiveness of the strategy itself in validating the mental models data. The evaluation was conducted using postal questionnaires and semi-structured verbal protocols to provide responses to the alternative intervention content and to prioritize risk messages. User discussion groups were then employed, particularly as a means of establishing whether contextual information could be obtained that would differ qualitatively from the kind elicited through individual (semi) structured methods. We conclude that the mental models approach as part of an iterative process including systematic multimethod evaluation is successful in supporting the design of relevant communications to the users of chemicals. The overall viability of communicative interventions in the context of health and safety in small businesses remains in question. Future research might aim to develop a more holistic approach to interventions in complex occupational contexts.     

论高校贷款办学风险及其防范

高校为了适应高等教育大众化的要求,扩大办学规模,加快发展高等教育事业,同时为了解决资金紧缺而引入贷款机制.文章对贷款所产生的风险进行分析,揭示贷款风险不良后果的主要表现,并在风险防范方面提出了若干建议.     

"一带一路"背景下中国海外利益在小国的保护研究

在推进“一带一路”中,中国在小国的物质性与非物质性海外利益均面临风险,原因主要有内外两个方面:从内部看,对小国尚存错误认知,人文外交总体规划待完善,也存在着企业或个人的不规范行为;从外部看,“一带一路”沿线小国的脆弱性、对外依赖性及边缘性特征导致中国的海外利益遭受风险。中国应根据海外利益的具体风险状况及遭受风险原因制定措施,从自身出发,纠正对小国的错误认知,建立小国专属投资政策,增强针对小国的避险意识,开展有效宣传以改善中国形象;针对小国特性,提高应对突发事件能力,增强对小国的战略惩戒能力。从而有效保护中国在“一带一路”沿线小国的海外利益,并为沿线小国稳步构建命运共同体服务。     

“网运分离”模式下我国铁路运输业路运的竞争

为铁路运输业引入竞争以提高其效率,是一切改革方案的最终目的。“网运分离”模式为此提供了可能。虽然从理论上分析,“网运分离”后铁路运输业存在多种竞争形式,但真正有效的是线路运营权的竞争和与其它运输方式间的竞争两种。从有效竞争理论和可竞争市场理论分析,在我国铁路运输业引入竞争,需要政府、企业、社会多方面的努力。     

代耕农——新农村建设中的“租约农民”——以惠州博罗县石湾镇铁场村为例

近年来,随着珠江三角洲地区工业化步伐进程的加快与地区经济差异扩大,发达地区农民将田地以签定合同或达成口头协议的方式租给落后地区农民耕种,出现了“代耕农”群体。由于与传统的租佃关系形成制度背景不同,产生了新型的农业租佃关系。本文分析了新型的农业租佃关系构成,与传统农业租佃关系进行了比较,并进一步对“新农村”建设中“租约”农民的问题提出了一些建议。     

中国转型期的社会安全隐患与对策

中国转型期面临着严重的社会安全隐患,具体表现为多重风险共生、社会自身在保障安全方面具有脆弱性、社会应对风险的思维具有极化倾向。为了走向更加安全的社会,不仅要充分认识社会安全问题的重要性,而且要完善风险管理体系,实施多元化风险管理策略,正确认识国家的作用,高度重视风险教育,积极实践新型发展观。     

Mixtures of Toxic Agents and Attributable Risk Calculations

Calculations of attributable risks have attracted increasing interest recently. However, these efforts have been limited to mostly one agent, radiation, and no interactions with effects of other toxic agents have been taken into account. This paper outlines a generic approach to the calculation of attributable risks for an exposure to several toxic agents and interaction effects associated with them. In this calculation, the partition of interaction terms between the agents responsible is of particular importance. At present, there are no rules on how to assign equitable shares, so one methodology will be proposed and others discussed briefly. For one example of an assignment, the standard errors of the attributable risks are determined in terms of the uncertainties of the input parameters, thus setting the stage for a comparison of the different shares of responsibility.