Some results on generalized ageing classes

In this paper we provide new results about generalized ageing classes on the excess lifetime of a renewal process. We also obtain some characterizations of generalized ageing classes by means of the residual life at random time.     

三大冲突的交融:中国资本流动性过剩内在机理分析

当前中国宏观经济面临诸多问题,其重要原因就在于中国资本流动性过剩.而资本流动性过剩产生的实质则是三大冲突的交融:即实体经济与虚拟经济的冲突,转轨期新体制与旧体制的冲突和开放经济下内外均衡的冲突.为此解决中国宏观经济运行矛盾的突破口在于解决资本流动性过剩,其战略思路应该以金融全球化背景为出发点,适应国际货币体系调整,以国家安全作为重点,实现三大均衡:一是实体经济和虚拟经济的均衡;二是新旧体制交叉期的制度均衡;三是开放条件下内外均衡.     

Binomial Mixture Modeling of University Credits

The paper reviews finite mixture models for binomial counts with concomitant variables. These models are well known in theory, but they are rarely applied. We use a binomial finite mixture to model the number of credits gained by freshmen during the first year at the School of Economics of the University of Florence. The finite mixture approach allows us to appropriately account for the large number of zeroes and the multimodality of the observed distribution. Moreover, we rely on a concomitant variable specification to investigate the role of student background characteristics and of a compulsory pre-enrollment test in predicting gained credits. In the paper, we deal with model selection, including the choice of the number of components, and we devise numerical and graphical summaries of the model results in order to exploit the information content of the concomitant variable specification. The main finding is that the introduction of the pre-enrollment test gives additional information for student tutoring, even if the predictive power is modest.     

A characterization of the dilation order and its applications

LetX andY be two random variables with finite expectationsE X andE Y, respectively. ThenX is said to be smaller thanY in the dilation order ifE[ϕ(X-E X)]≤E[ϕ(Y-E Y)] for any convex functionϕ for which the expectations exist. In this paper we obtain a new characterization of the dilation order. This characterization enables us to give new interpretations to the dilation order, and using them we identify conditions which imply the dilation order. A sample of applications of the new characterization is given. Partially supported by MURST 40% Program on Non-Linear Systems and Applications. Partially supported by “Gruppo Nazionale per l'Analisi Funzionale e sue Applicazioni”—CNR.     

A robust version of the hurdlemodel

The excess of zeros is not a rare feature in count data. Statisticians advocate the Poisson-type hurdle model (among other techniques) as an interesting approach to handle this data peculiarity. However, the frequency of gross errors and the complexity intrinsic to some considered phenomena may render this classical model unreliable and too limiting. In this paper, we develop a robust version of the Poisson hurdle model by extending the robust procedure for GLM of Cantoni and Ronchetti (2001) to the truncated Poisson regression model. The performance of the new robust approach is then investigated via a simulation study, a real data application and a sensitivity analysis. The results show the reliability of the new technique in the neighborhood of the truncated Poisson model. This robust modelling approach is therefore a valuable complement to the classical one, providing a tool for reliable statistical conclusions and to take more effective decisions.     

Partial Ordering and Aging Properties of Order Statistics When the Sample Size is Random: A Brief Review

In many practical situations, order statistics arise naturally with random sample size. In this article, we review results on partial orderings and aging properties of such order statistics. The comparison of order statistics for different sample sizes is also discussed here.     

A fourth order rotatable design in three dimensions

The necessary and sufficient conditions for a set of points to form a rotatable design of order four have been given by Patel and Arapkoske (1985). One such set of 104 points for three factors which satisfies these conditions is given in this paper.     

从PPI变化看当前稳增长与化解过剩产能

我国经济稳增长必须把化解过剩产能作为一项重要任务,这既是减少经济波动的需要,也是转变经济发展方式,为新兴产业发展腾笼换鸟的必然要求。建议多管齐下,实行五大战略:坚持实施扩大内需战略,大力促进消费需求增长和稳步推进城市化;坚持实施"走出去"战略,积极拓展国际新兴市场和转移国内过剩生产能力;坚持实施产业创新升级战略,大力优化行业技术和产品结构;坚持实施淘汰落后产能战略,严格控制过剩行业产能扩张;坚持建立健全产业引导调控战略,促进产业有序竞争发展。     

Hexavalent Chromium and Lung Cancer in the Chromate Industry: A Quantitative Risk Assessment

The purpose of this investigation was to estimate excess lifetime risk of lung cancer death resulting from occupational exposure to hexavalent-chromium-containing dusts and mists. The mortality experience in a previously studied cohort of 2,357 chromate chemical production workers with 122 lung cancer deaths was analyzed with Poisson regression methods. Extensive records of air samples evaluated for water-soluble total hexavalent chromium were available for the entire employment history of this cohort. Six different models of exposure-response for hexavalent chromium were evaluated by comparing deviances and inspection of cubic splines. Smoking (pack-years) imputed from cigarette use at hire was included in the model. Lifetime risks of lung cancer death from exposure to hexavalent chromium (assuming up to 45 years of exposure) were estimated using an actuarial calculation that accounts for competing causes of death. A linear relative rate model gave a good and readily interpretable fit to the data. The estimated rate ratio for 1 mg/m3-yr of cumulative exposure to hexavalent chromium (as CrO3), with a lag of five years, was RR=2.44 (95% CI=1.54-3.83). The excess lifetime risk of lung cancer death from exposure to hexavalent chromium at the current OSHA permissible exposure limit (PEL) (0.10 mg/m3) was estimated to be 255 per 1,000 (95% CI: 109-416). This estimate is comparable to previous estimates by U.S. EPA, California EPA, and OSHA using different occupational data. Our analysis predicts that current occupational standards for hexavalent chromium permit a lifetime excess risk of dying of lung cancer that exceeds 1 in 10, which is consistent with previous risk assessments.     

基于货币需求的我国流动性过剩成因分析

区别于以往对流动性的研究,本文基于流动性定义,从货币需求角度对货币流动性需求的形成、货币流动性供给限制和货币流动性实现机制的一般规律进行了探讨,以此为基础分析了我国流动性过剩形成的原因,即:由于我国金融体制缺乏有效风险防控机制,形成了当前社会财富总值和流动性货币需求的互为因果、互为促进的恶性循环。从这一结论出发指出了流动性过剩对我国国民经济的危害并针对性的提出了政策建议。