Simultaneous sparse model selection and coefficient estimation for heavy-tailed autoregressive processes

We propose a sparse coefficient estimation and automated model selection procedure for autoregressive processes with heavy-tailed innovations based on penalized conditional maximum likelihood. Under mild moment conditions on the innovation processes, the penalized conditional maximum likelihood estimator satisfies a strong consistency, O_P(N^?1/2) consistency, and the oracle properties, where N is the sample size. We have the freedom in choosing penalty functions based on the weak conditions on them. Two penalty functions, least absolute shrinkage and selection operator and smoothly clipped average deviation, are compared. The proposed method provides a distribution-based penalized inference to AR models, which is especially useful when the other estimation methods fail or under perform for AR processes with heavy-tailed innovations [Feigin, Resnick. Pitfalls of fitting autoregressive models for heavy-tailed time series. Extremes. 1999;1:391–422]. A simulation study confirms our theoretical results. At the end, we apply our method to a historical price data of the US Industrial Production Index for consumer goods, and obtain very promising results.     

盛名难副: 明星 CEO 与负面信息隐藏

以 2009 年 ～ 2016 年间 A 股上市公司为研究样本，采用双重差分法研究明星 CEO 成名后负面信息的披露策略． 以 CEO 是否登上媒体发布的榜单作为明星 CEO 的代理变量，研究结果表明: 明星 CEO 上榜将显著增加隐藏负面信息的可能性，验证了“名声俘获假说”; 明星CEO上榜后发生财务重述的概率显著增加，而一旦退出榜单其隐藏负面信息的可能性则显著降低，验证了名声的负面效应． 机制检验表明明星 CEO 通过管理层权力抑制负面信息披露． 另 外，上榜前盈余质量较低、代理问题较严重的公司，其明星 CEO 隐藏负面信息的可能性更高．文章丰富了 CEO 个人特质对信息披露行为的影响及其经济后果的研究，对于资本市场的健康发展具有一定的启示意义．     

以科学态度对待中国文化或文学传统

弘扬中华民族的优秀文化文学传统,其深远历史意义与重大现实意义无论怎样估价都不会过分。然而,在当下"国学热"中却出现了一些令人忧思的症候:读经复古,诋毁或否定五四新文化、新文学运动的历史意义便是其中显著的两种。应该以科学态度对这两种症候进行深度剖析,对中国文化、特别是儒家文化传统以及五四新文化新文学的"反传统"给出实事求是的科学阐释。     

Efficient Estimation of an Additive Quantile Regression Model

Abstract. In this paper, two non‐parametric estimators are proposed for estimating the components of an additive quantile regression model. The first estimator is a computationally convenient approach which can be viewed as a more viable alternative to existing kernel‐based approaches. The second estimator involves sequential fitting by univariate local polynomial quantile regressions for each additive component with the other additive components replaced by the corresponding estimates from the first estimator. The purpose of the extra local averaging is to reduce the variance of the first estimator. We show that the second estimator achieves oracle efficiency in the sense that each estimated additive component has the same variance as in the case when all other additive components were known. Asymptotic properties are derived for both estimators under dependent processes that are strictly stationary and absolutely regular. We also provide a demonstrative empirical application of additive quantile models to ambulance travel times.     

我国南珠产业的困境及其治理研究

在我国具有悠久历史的南珠产业,因环境和效益的双重制约而不得不面对能否继续存在的困境.这并非偶然,而是政府、市场和社区同时失灵的一种必然结果,其根源在于缺乏合理的产业政策和管理框架.南珠产业要实现可持续发展,公共政策当有所作为.其主要任务是根除“公地悲剧”和“劣币驱逐良币”等问题的制度性诱因,引导产业实现从规模粗放扩张向精品集约发展的转变.当务之急是:明确南珠产业发展目标,建立产业保护区,开展海域利用空间规划,修正现行海域利用规则,加强珍珠市场监管,培育行业自我组织和管理能力,创设珍珠养殖风险基金.     

A quantile-based study on ageing intensity function

Jiang, Ji, and Xiao (2003 Jiang, R., P. Ji, and X. Xiao. 2003. Aging property of unimodal failure rate models. Reliability Engineering and System Safety 79(1):113–6.[Crossref], [Web of Science ®] , [Google Scholar]) has introduced a quantitative measure known as the ageing intensity function for evaluating the ageing properties of a component/system. In recent years, there has been a great interest on the study of quantile function, an equivalent alternative to the distribution function approach. Unlike the distribution function approach, the quantile method possess some unique properties (see Gilchrist 2000 Gilchrist, W. 2000. Statistical modelling with quantile functions. Boca Raton, Florida: Chapman and Hall/CRC.[Crossref] , [Google Scholar], Nair, Sankaran, and Balakrishnan 2013 Nair N. U., P. G. Sankaran, N. Balakrishnan. 2013. Quantile-based reliability concepts. In: Quantile-Based Reliability Analysis. Statistics for Industry and Technology. New York, NY: Birkhäuser.[Crossref] , [Google Scholar]). Motivated with this, in the present paper we introduce a quantile-based ageing intensity function and study its various ageing properties. We also study some stochastic comparison of random variables based on the proposed measure.     

Large sample behavior of the Bernstein copula estimator

Bernstein polynomial estimators have been used as smooth estimators for density functions and distribution functions. The idea of using them for copula estimation has been given in Sancetta and Satchell (2004). In the present paper we study the asymptotic properties of this estimator: almost sure consistency rates and asymptotic normality. We also obtain explicit expressions for the asymptotic bias and asymptotic variance and show the improvement of the asymptotic mean squared error compared to that of the classical empirical copula estimator. A small simulation study illustrates this superior behavior in small samples.     

俄语名词的计量特征研究

传统语法主要采用定性方法对语言作出描述,而计量语言学采用统计方法,利用（经过句法标注的）语料库对语言进行定量分析,是对语言进行精确研究的有效途径。以俄罗斯科学院编制的STR树库为数据来源,通过从树库中提取由名词充当支配词构成的名词性结构的相关数据,对名词性结构的基本类型、词序特征及其句法功能进行统计分析,得到了三个研究结果：一是验证了传统语法中已有的定论;二是使这些定论得到了更为精确的阐释;三是发现了传统研究方法难以发现的一些俄语名词的结构规律。由此可见,采用计量方法对词类的句法进行研究,不仅可以从定量的角度对传统语法中的有关论述加以补充与完善,而且具有语言类型学的意义。     

高职可持续发展的基础：“双师型”师资队伍建设

加强教师队伍建设是教育事业发展最重要的基础工作。高等职业教育同时具有＂高等教育＂和＂职业教育＂的双重属性,因此加强＂双师型＂师资队伍建设是高等职业教育事业发展的最重要的基础工作,对高等职业教育的可持续发展具有十分重要的意义。     

关于应收账款的管理

随着改革开放的发展和社会主义市场经济的建立,市场竞争越来越激烈,企业在相互竞争中,越来越注重促销手段,赊销成为企业扩大销售,促进利润增加的重要手段之一。但应收账款的拖欠也成为很多企业被拖垮的重要原因之一。本文从应收账款形成的原因出发,阐述了应收账款对企业的影响,并提出了加强应收账款管理的措施。