线性模型误差方差估计的精确极限性质

本文讨论线性模型Yi=Xi1β ei,i=1,2,…,n,其中{ei,i=1,2,…,n)为零均值方差有限 的独立同分布随机变量序列,分别证明了模型的误差方差估计的LLN和LIL精确极限性质.     

Symmetry and nonexistence of positive solutions to an integral system with weighted functions

Consider the system of integral equations with weighted functions in Rn,{u(x) =∫Rn|x-y|α-nQ(y)v(y)qdy1,v(x)=∫Rn|x-y|α-nK(y)u(y)pdy,where 0 < α < n,1/(p+1) + 1/(q+1)≥(n-α)/n1,α/(n-α) < p1q < ∞1,Q(x) and K(x) satisfy some suitable conditions.It is shown that every positive regular solution(u(x)1,v(x)) is symmetric about some plane by developing the moving plane method in an integral form.Moreover,regularity of the solution is studied.Finally,the nonexistence of positive solutions to the system in the case 0 <...     

不做“数豆者”十诫

“数豆者”,这一略带贬义的名词在上世纪50年代中期就已经泛指会计人员。对于非财会员工而言,“数豆者”代表了这样一种人物形象：他们不是整天摆弄着计算器,试图从各种费用中节省部分金额,就是忙于制定各种表格并填充数据,用来支持管理层裁员或砍掉项目的决策。在这样先入为主的负面印象下,很难就会计如何为企业增加价值展开沟通。     

A nonparametric estimation of the infection curve

Predicting the future course of an epidemic depends on being able to estimate the current numbers of infected individuals.However,while back-projection techniques allow reliable estimation of the numbers of infected individuals in the more distant past,they are less reliable in the recent past.We propose two new nonparametric methods to estimate the unobserved numbers of infected individuals in the recent past in an epidemic.The proposed methods are noniterative,easily computed and asymptotically normal wit...     

IT是一种投资

很多管理者都是从专业领域做起,逐步发展,直至参与企业战略制订,而财务专业的知识在此进程中是非常重要的。相对于那些没有财务背景的人,一个精通于财务的管理者可以更全面地了解企业的情况。     

风险管理藏风险

风险管理时代已经来临。越来越多的机构开始聘请专业的风险管理人员,企业主要的董事会成员甚至是CEO,直接负责风险管理的具体事务。这到底是不是一件好事？或许不少机构的风险管理体系能因此得重叠明显改进,但有些却可能由于缺少战略上的清晰定位,变得更糟。     

On a robust and effcient maximum depth estimator

The best breakdown point robustness is one of the most outstanding features of the univariate median.For this robustness property,the median,however,has to pay the price of a low effciency at normal and other light-tailed models.Affine equivariant multivariate analogues of the univariate median with high breakdown points were constructed in the past two decades.For the high breakdown robustness,most of them also have to sacrifice their effciency at normal and other models,nevertheless.The affine equivariant...     

多元线性混合模型方差分量矩阵的非负估计

本文研究了带有两个方差分量矩阵的多元线性混合模型方差分量矩阵的估计问题.对于平衡模型,给出了基于谱分解估计的一个方差分量矩阵的非负估计类.对于非平衡模型,给出了方差分量矩阵的广义谱分解估计类,讨论了与ANOVA估计等价的充要条件.同时,在广义谱分解估计的基础上给出了一种非负估计类,并讨论了其优良性.当具有较小二次风险的非负估计不存在时,从估计为非负的概率的角度考虑,将Kelly和Mathew(1993)提出的构造具有更小取负值概率的估计类的方法推广到本文的多元模型下,给出了较谱分解估计相比有更小取负值概率和更小风险的估计类.最后,模拟研究和实例分析表明文中理论结果有很好的表现.     

Model averaging for semiparametric additive partial linear models

To improve the prediction accuracy of semiparametric additive partial linear models(APLM) and the coverage probability of confidence intervals of the parameters of interest,we explore a focused information criterion for model selection among ALPM after we estimate the nonparametric functions by the polynomial spline smoothing,and introduce a general model average estimator.The major advantage of the proposed procedures is that iterative backfitting implementation is avoided,which thus results in gains in co...     

用好EVA指挥棒——EVA，一个讲实话的指标

经济增加值（EVA）被誉为20世纪末“最炙手可热的财务概念”,财经产生便受到国际上著名大公司的推崇,作为一个被称作是一个“真正能够讲实话”的指标,亦受到了中国企业的广泛关注。