Acceptance sampling based on truncated life tests for generalized Rayleigh distribution

This paper considers the problem of an acceptance sampling plan for a truncated life test when the lifetime follows the generalized Rayleigh distribution. For different acceptance numbers, confidence levels, and values of the ratio of the fixed experiment time to the specified mean life, the minimum sample sizes necessary to ensure the specified mean life are found. The operating characteristic values of the sampling plans and producer's risk are discussed. Some tables are presented and the use of the tables is illustrated by a numerical example.     

A robust prediction error criterion for pareto modelling of upper tails

Estimation of the Pareto tail index from extreme order statistics is an important problem in many settings. The upper tail of the distribution, where data are sparse, is typically fitted with a model, such as the Pareto model, from which quantities such as probabilities associated with extreme events are deduced. The success of this procedure relies heavily not only on the choice of the estimator for the Pareto tail index but also on the procedure used to determine the number k of extreme order statistics that are used for the estimation. The authors develop a robust prediction error criterion for choosing k and estimating the Pareto index. A Monte Carlo study shows the good performance of the new estimator and the analysis of real data sets illustrates that a robust procedure for selection, and not just for estimation, is needed.     

Risk of Error and the Kappa Coefficient of a Binary Diagnostic Test in the Presence of Partial Verification

The accuracy of a binary diagnostic test is usually measured in terms of its sensitivity and its specificity, or through positive and negative predictive values. Another way to describe the validity of a binary diagnostic test is the risk of error and the kappa coefficient of the risk of error. The risk of error is the average loss that is caused when incorrectly classifying a non-diseased or a diseased patient, and the kappa coefficient of the risk of error is a measure of the agreement between the diagnostic test and the gold standard. In the presence of partial verification of the disease, the disease status of some patients is unknown, and therefore the evaluation of a diagnostic test cannot be carried out through the traditional method. In this paper, we have deduced the maximum likelihood estimators and variances of the risk of error and of the kappa coefficient of the risk of error in the presence of partial verification of the disease. Simulation experiments have been carried out to study the effect of the verification probabilities on the coverage of the confidence interval of the kappa coefficient.     

网上购物风险来源、类型及其影响因素研究

从风险来源的角度深入地研究了网上购物感知风险类型与其相对强度,对于企业从风险来源上降低和管理网上风险具有重要的指导意义.文章发现消费者在网上购物时,风险主要来源于产品本身、远距离交易、互联网这种交易模式和网站这四个方面.研究结果揭示了,当消费者在网上购物的时候,所感受到最强烈的三个风险分别是,来自于产品本身的产品绩效风险、来自于远距离交易的服务风险和来自于网站的来源风险.最后,研究还发现,消费者网上购物感知风险的强弱与消费者的年龄、网络购物频率之间存在较强的相关性,年龄越大,感知风险越强;网上购物频率越高,感知风险越低.     

基于管理式医疗的全民社会医疗保险初探

管理式医疗是美国占主导地位的医疗保险形式,可以看成是医疗保险公司运用期权思想管理风险的一种风险管理模式.深入剖析了我国医疗保险现存的问题,在公平与效率兼顾的基础上,借鉴美国管理式医疗的风险管理方法,提出了适合我国国情的全民社会医疗保险模式的构想,即以政府委托社会保障部门作为管理式医疗组织者,通过买入社区医疗服务网络这个买方期权,对冲其对投保人承担的卖出买方期权的风险,建立社会保障部门、社区医疗服务机构和投保人三方三位一体的风险管理模式.     

Multiobjective Decision-Tree Analysis1

Single-objective-based decision-tree analysis has been extensively and successfully used in numerous decision-making problems since its formal introduction by Howard Raiffa more than two decades ago. This paper extends the traditional methodology to incorporate multiple noncommensurate objective functions and use of the conditional expected value of the risk of extreme and catastrophic events. The proposed methodology considers the cases where (a) a finite number of actions are available at each decision node and (b) discrete or continuous states of nature can be presented at each chance node. The proposed extension of decision-tree analysis is introduced through an example problem that leads the reader step-by-step into the methodological procedure. The example problem builds on flood warning systems. Two noncommensurate objectives—the loss of lives and the loss of property (including monetary costs of the flood warning system)–are incorporated into the decision tree. In addition, two risk measures—the common expected value and the conditional expected value of extreme and catastrophic events—are quantified and are also incorporated into the decision-making process. Theoretical difficulties associated with the stage-wise calculation of conditional expected values are identified and certain simplifying assumptions are made for computational tractibility. In particular, it is revealed that decisions concerning experimentation have a very interesting impact on the noninferior solution set of options—a phenomenon that has no equivalence in the single-objective case.     

我国现代物流的风险及物流保险需求分析

物流业已成为近几年我国经济领域中最活跃、最热门的新兴行业之一,第三方物流形态正引起人们的重视,其发展空间很大。但我国现代物流运行却涉及制度和法律风险、合同风险以及责任范围加大的风险。在现代物流中传统保险不能解决第三方物流公司面临的代位追偿等问题,而2004年推出的物流保险也存在物流保险责任范围小、计收保费依据不科学、不能满足快速发展的市场需求等缺陷。因此,我国急需发展现代物流综合保险,而根据物流市场的需要,进一步开发适销对路的险种是其中的关键。第三方物流企业也应根据需要选择物流综合保险策略,从而降低风险。     

科技型人才聚集环境及聚集效应分析(一)——制度环境对科技型人才聚集效应的影响分析

制度环境是影响科技型人才聚集效应产生与提升的重要环境因素。在论述了科技型人才聚集效应概念和特征的基础上,分析了制度环境的内涵,从人才身份管理制度、人才配置制度、人才产权制度、人才使用制度以及人才激励制度五方面探讨了制度环境对科技型人才聚集效应的影响,提出了优化我国制度环境的对策,以促进科技型人才聚集经济性效应的产生与提升。     

非对称信息下证券公司道德风险定价模型的研究

由于证券市场上非对称信息状态的存在,信息差别给证券投资者保护制度带来了不容忽视的道德风险结果,本文通过建立证券公司道德风险定价模型,计算出了证券公司向证券投资者保护基金机构缴纳保护基金的费率基准。据此,在保护证券投资者利益的基础上,证券投资者保护基金机构可以向证券公司按照给出的费率基准收取保护基金,从而减少证券公司道德风险的发生。     

基于CIR模型的利率风险计量及实证——以我国国债市场为例

本文以我国国债市场为例,利用4种期限类型(7年期、8年期、10年期和20年期)的国债收益率样本数据对CIR模型进行实证分析得出,CIR模型较适宜于中国当前的金融市场实际;在实证研究中,考虑广义矩方法(GMM)可能存在某些问题,如效率不高。并且使用Nowman(1997)提出的最大似然估计法(MLE)对上述利率动态模型进行估计。在此基础上,构建了基于利率期限结构的久期模型并进行经验计算。