Failure Probability Under Parameter Uncertainty

In many problems of risk analysis, failure is equivalent to the event of a random risk factor exceeding a given threshold. Failure probabilities can be controlled if a decisionmaker is able to set the threshold at an appropriate level. This abstract situation applies, for example, to environmental risks with infrastructure controls; to supply chain risks with inventory controls; and to insurance solvency risks with capital controls. However, uncertainty around the distribution of the risk factor implies that parameter error will be present and the measures taken to control failure probabilities may not be effective. We show that parameter uncertainty increases the probability (understood as expected frequency) of failures. For a large class of loss distributions, arising from increasing transformations of location‐scale families (including the log‐normal, Weibull, and Pareto distributions), the article shows that failure probabilities can be exactly calculated, as they are independent of the true (but unknown) parameters. Hence it is possible to obtain an explicit measure of the effect of parameter uncertainty on failure probability. Failure probability can be controlled in two different ways: (1) by reducing the nominal required failure probability, depending on the size of the available data set, and (2) by modifying of the distribution itself that is used to calculate the risk control. Approach (1) corresponds to a frequentist/regulatory view of probability, while approach (2) is consistent with a Bayesian/personalistic view. We furthermore show that the two approaches are consistent in achieving the required failure probability. Finally, we briefly discuss the effects of data pooling and its systemic risk implications.     

产蛋鸡饲粮中添加磷脂的效果试验

选用罗曼褐壳蛋鸡152只．随机分成4组,基础饲报中添加0．5％、10％和1．5％磷脂为试验组,试验期30d。试验结果表明：各组间平均蛋重天显著性差异（P＞0．05）;添加1．5％磷脂的试验Ⅲ组在产蛋数、产蛋率方面均极显著高于对照组和其他试验组（P＜0．01）：试验Ⅲ组的料蛋比显著低于其他组,但蛋破损率较高。     

Modified BLUEs and BLIEs of the location and scale parameters and the population mean using ranked set sampling

Ranked set sampling (RSS) is a sampling procedure that can be used to improve the cost efficiency of selecting sample units of an experiment or a study. In this paper, RSS is considered for estimating the location and scale parameters a and b>0, as well as the population mean from the family F((x?a)/b). Modified best linear unbiased estimators (BLUEs) and best linear invariant estimators (BLIEs) are considered. Numerical computations with different location-scale distributions and different sample sizes are conducted to assess the efficiency of the suggested estimators. It is found that the modified BLIEs are uniformly higher than that of BLUEs for all distributions considered in this study. The modified BLUE and BLIE are more efficient when the underlying distribution is symmetric.     

On Pitman's measure of closeness of k-records

Pitman closeness of both the upper and lower k-record statistics to the population quantiles of a location–scale family of distributions is studied. For the population median, the Pitman-closest k-record is also determined. In the case of symmetric distributions, the Pitman closeness probabilities of k-record statistics are shown to be distribution-free, and explicit expressions are also derived for these probabilities. Exact expressions are derived for the required probabilities for uniform and exponential distributions. Numerical results are given for these families and also the Pitman-closest k-record is determined.     

Linear estimation for the extended exponential power distribution

Tiao and Lund [The use of OLUMV estimators in inference robustness studies of the location parameter of a class of symmetric distributions. J Amer Statist Assoc. 1970;65(329):370–386] tabulated the coefficients of the best linear unbiased estimators (BLUEs) of location and scale for a particular family of symmetric distributions. This family was a reparameterization of the extended exponential power distribution (EEPD) with the shape parameter restricted to be greater than or equal to one. In this work, we consider the BLU estimation of the location and scale parameters of the EEPD when the shape parameter is one-third and one-half. We obtain closed-form expressions for the single and product moments of the order statistics when the shape parameter is in general in the form of a reciprocal of an integer. These expressions are then used to determine the BLUEs and the corresponding variances for complete samples of size 20 and less. We consider some other linear estimators of the location and scale parameters and then compare them with the BLUEs. Finally, we present a numerical example to illustrate the developed results.     

人口、经济总量、经济结构及技术进步对中国S02影响的实证分析——对Grossman污染分解方程的拓展

通过对Grossman污染分解方程进行拓展,加入了人口增长效应、收入效应,并对技术效应进行了进一步的分解,建立了新的污染物分解动态方程,以探讨影响污染物排放量的各种效应。在此基础之上,利用动态计量经济学的方法,以中国1985到2008年S02排放的数据进行分析,验证了人口增长效应是S02增加的重要原因;技术效应对减少S02的排放起到的作用逐渐加大。因此,在人口众多的中国,影响污染物排放的因素应该考虑到人口的规模效应。另外,国家需要继续加大能源利用技术和污染物处理技术的研发和应用来减少环境污染。     

ROC Curves in Non‐Parametric Location‐Scale Regression Models

Abstract. The receiver operating characteristic (ROC) curve is a tool of extensive use to analyse the discrimination capability of a diagnostic variable in medical studies. In certain situations, the presence of a covariate related to the diagnostic variable can increase the discriminating power of the ROC curve. In this article, we model the effect of the covariate over the diagnostic variable by means of non‐parametric location‐scale regression models. We propose a new non‐parametric estimator of the conditional ROC curve and study its asymptotic properties. We also present some simulations and an illustration to a data set concerning diagnosis of diabetes.     

信息化、成本优势与小企业的规模有效性

近年来,相对于小型企业来说,大中型企业在市场份额和单位数比重方面持续下滑的趋势相当明显。根据施蒂格勒的“适存论”,相对于“大中型”来说,“小型”似乎成了当前市场上更有效的规模形态。这一现象的背后到底隐藏着怎样的逻辑？通过构建中国制造业2003--2009年间的面板数据模型,实证验证信息化对于提升“小型”这种规模形态之有效性的正面影响,以及生产成本和协调成本在信息化与企业规模有效性之间的中介作用。以期为本土制造业更加有效地利用信息化机遇构建核心竞争优势、实现新的产业发展提供决策借鉴。     

用古代五行学说组建企业高层管理团队的研究

管理团队是近些年在管理学上的讨论热点 ,西方国家已对其进行了较多的研究。文章在阐述了中国古代五行学说的理论基础上 ,对企业内高层管理团队的角色进行了五形人的探讨 ,并对管理团队职位的生克乘侮关系和组建规模进行了分析研究。     

论增强党性与克服自由主义

自由主义在新的历史条件下有各种表现 ,它的危害性不可低估。自由主义得以泛滥的重要原因是党员的党性不强。因此 ,加强党性锻炼 ,提高抵御自由主义侵蚀的自觉性 ,确有必要。