关于平均一致凸Banach空间

给出平均一致凸Ｂａｎａｃｈ空间的定义，证明了一致凸Ｂａｎａｃｈ空间是平均一致凸Ｂａｎａｃｈ空间，平均一致凸Ｂａｎａｃｈ空间是自反和弱局部一致凸Ｂａｎａｃｈ空间，并且平均一致凸Ｂａｎａｃｈ空间Ｘ中任意元在Ｘ的闭凸子集中存在唯一的最佳逼近元．     

一种802.11DCF性能分析的简单方法

为了简化全互连环境饱和情况下IEEE802.11DCF的性能分析方法,采用了一种简单的盒子-球模型。研究了将活跃结点发送报文时的碰撞转换成对相同数目的球独立随机放入多个盒子问题,盒子数目与活跃节点的平均竞争窗口相关。当有多个球恰巧落入同一个盒子中时,表明相应时刻会有碰撞发生。针对结点重发次数有限的实际情况,将发送结点的状态变化看作一个一维有限状态的马尔可夫过程,提出了一种基于虚发送周期和平均竞争窗口的计算802.11DCF容量的简单方法。仿真结果验证了该方法的合理性。     

The effects of different choices of order for autoregressive approximation on the Gaussian likelihood estimates for ARMA models

This paper investigates, by means of Monte Carlo simulation, the effects of different choices of order for autoregressive approximation on the fully efficient parameter estimates for autoregressive moving average models. Four order selection criteria, AIC, BIC, HQ and PKK, were compared and different model structures with varying sample sizes were used to contrast the performance of the criteria. Some asymptotic results which provide a useful guide for assessing the performance of these criteria are presented. The results of this comparison show that there are marked differences in the accuracy implied using these alternative criteria in small sample situations and that it is preferable to apply BIC criterion, which leads to greater precision of Gaussian likelihood estimates, in such cases. Implications of the findings of this study for the estimation of time series models are highlighted.     

教育与人力资本分布状况对我国经济增长的影响

如果用人均受教育年限和教育基尼系数这两个指标来衡量我国的教育分布状况,我们就会发现:我国居民总体的受教育程度仍然偏低,人力资本平均水平和教育分配的不平等程度对经济增长分别有正的和负的影响,东部和中部地区对人力资本分布平等性的依赖程度要超过西部。为了改善我国教育分布状况,应大力普及义务教育、允许多种形式的教育投入和建立学费听证会制度,以促进教育的公平增长。     

对房价——收入衡量指标的修正

针对房价收入比指标衡量区域房地产价格与居民收入水平关系中的不足,提出人均住宅有效购买力系数的概念,阐述该指标的优点,并用该指标对1987年以来中国人均住宅有效购买力的变化和截止2004年底37个大中城市人均有效购买力的横向对比做了实证分析,进而探讨了建构中国房地产市场统计指标体系的新思路。     

A SIMPLE SEQUENTIAL WILCOXON TEST

A simple sequential non-parametric test for the two-sample problem is proposed. A method of deriving its O.C. and A.S.N. funtions is given, and their adequacy confirmed by simulation. The test is found to require about 10 percent more observations than an optimal rank test; however it is much easier to apply. The test is found to be relatively robust.     

论市场经济条件下的按劳分配

"按劳分配"是一种平等的价值观在经济领域的体现,中国当今不存在实现马克思意义上的按劳分配所要求的条件,从而也不存在马克思意义上的按劳分配.市场经济条件下劳动力要素的流动性、平均工资率的形成,同样可以实现按劳分配,但已不是马克思意义上的了.     

A Multivariate Adaptive Exponentially Weighted Moving Average Control Chart

A multivariate extension of the adaptive exponentially weighted moving average (AEWMA) control chart is proposed. The new multivariate scheme can detect small and large shifts in the process mean vector effectively. The proposed scheme can be viewed as a smooth combination of a multivariate exponentially weighted moving average (MEWMA) chart and a Shewhart χ²-chart. The optimal design of the proposed chart is given according to a pre-specified in-control average run length and two shift sizes; a small and large shift each measured in terms of the non centrality parameter. The signal resistance of the newly proposed multivariate chart is also given. Comparisons among the new chart, the MEWMA chart, and the combined Shewhart-MEWMA (S-MEWMA) chart in terms of the standard and worst-case average run length profiles are presented. In addition, the three charts are compared with respect to their worst-case signal resistance values. The proposed chart gives somewhat better worst-case ARL and signal resistance values than the competing charts. It also gives better standard ARL performance especially for moderate and large shifts. The effectiveness of our proposed chart is illustrated through an example with simulated data set.     

Sliced Average Variance Estimation for Censored Data

We consider a nonlinear censored regression problem with a vector of predictors. With censoring, high-dimensional regression analysis becomes much more complicated. Since censoring can cause severe bias in estimation, modification to adjust such bias is needed to be made. Based on the weight adjustment, we develop the modification of sliced average variance estimation for estimating the lifetime central subspace without requiring a prespecified parametric model. Our proposed method preserves as much regression information as possible. Simulation results are reported and comparisons are made with the sliced inverse regression of Li et al. (1999 Li , K. C. , Wang , J. L. , Chen , C. H. ( 1999 ). Dimension reduction for censored regression data . Ann. Statist. 27 : 1 – 23 . [Google Scholar]).     

Conditional Information in Projections of Gaussian Vectors

Conditional information measures the information in a sample for an interest parameter in the presence of nuisance parameter. In the context of Gaussian likelihoods this paper first derives conditions under which a projection of the data may reduce conditional information to zero. These are then applied in the context of time series regressions, and inference on a covariance parameter, such as with either autoregressive or moving average errors. It is shown that regressing out very common regressors, such as a linear trend or dummy variable, can imply that conditional information is zero in the case of non-stationary autoregressions or non-invertible moving averages, respectively.