Procedure for determining sample size at each stage in group sequential test

The purpose of our study is to propose a. procedure for determining the sample size at each stage of the repeated group significance, tests intended to compare the efficacy of two treatments when a response variable is normal. It is necessary to devise a procedure for reducing the maximum sample size because a large number of sample size are often used in group sequential test. In order to reduce the sample size at each stage, we construct the repeated confidence boundaries which enable us to find which of the two treatments is the more effective at an early stage. Thus we use the recursive formulae of numerical integrations to determine the sample size at the intermediate stage. We compare our procedure with Pocock's in terms of maximum sample size and average sample size in the simulations.     

Further applications of bias to discriminant analysis

This article extends the biased minimum x² rule to the unequal covariance matrix case and to the case of several populations, The biased procedure is shown to improve the performance of the commonly used classification procedures. Results of sampling experiments over a broad range of conditions are provided to demonstrate this improvement.     

Gaussian Regularized Sliced Inverse Regression

Sliced Inverse Regression (SIR) is an effective method for dimension reduction in high-dimensional regression problems. The original method, however, requires the inversion of the predictors covariance matrix. In case of collinearity between these predictors or small sample sizes compared to the dimension, the inversion is not possible and a regularization technique has to be used. Our approach is based on a Fisher Lecture given by R.D. Cook where it is shown that SIR axes can be interpreted as solutions of an inverse regression problem. We propose to introduce a Gaussian prior distribution on the unknown parameters of the inverse regression problem in order to regularize their estimation. We show that some existing SIR regularizations can enter our framework, which permits a global understanding of these methods. Three new priors are proposed leading to new regularizations of the SIR method. A comparison on simulated data as well as an application to the estimation of Mars surface physical properties from hyperspectral images are provided.     

Does sequential augmenting of simple linear heteroscedastic regression reduce variances of ordinary least-squares estimators?

If uncorrelated random variables have a common expected value and decreasing variances, then the variance of a sample mean is decreasing with the number of observations. Unfortunately, this natural and desirable variance reduction property (VRP) by augmenting data is not automatically inherited by ordinary least-squares (OLS) estimators of parameters. We derive a new decomposition for updating the covariance matrices of the OLS which implies conditions for the OLS to have the VRP. In particular, in the case of a straight-line regression, we show that the OLS estimators of intercept and slope have the VRP if the values of the explanatory variable are increasing. This also holds true for alternating two-point experimental designs.     

司法成本及其节约与控制

司法是法律实施的重要途径和方式,是法律实现其目的和作用的保障。为了保证国家司法活动的正常进行,需要有一定的成本投入。在司法成本问题上,除了需要国家加大投入外,通过制度设计最大限度地节约和控制司法成本,让国家对司法的有限投入发挥其最大效益,是司法实践中需要认真研究的重要问题。     

中国能源密集型产品出口贸易的环境代价

一国出口产品本质上是在出口生产这种产品所密集使用的生产要素。能源密集型产品是中国出口贸易的大宗商品,其生产又是中国工业污染的主要来源之一。中国作为环境资源极为稀缺的国家,大量出口此类产品会导致中国在贸易中实际获取的比较利益比账面上获得的少,从而使中国应得的比较利益发生扭曲。由于环境影响往往具有隐蔽及难以用货币计量等特性,我国能源密集型产品出口贸易的环境代价长期被忽略。但随着环境容量资源的相对稀缺性日益增强,我国此类产品出口的环境代价日益凸现。矫正这一比较利益"扭曲"的有效途径可包括:(1)调整要素比价,改变目前我国资源低价、环境无价的价格体系不合理现象,逐步使我国出口此类产品的价格包含资源和环境的代价。(2)更好地运用清洁发展机制。     

Designing for equality: Conceptualising a tool for strategic territorial planning

The struggle for equality is fundamental to the reduction of poverty in Central America. Besides, one of the foremost goals of urban spatial planning, when implementing social policies, is to contribute to the reduction of poverty. This is done by producing a list of territorially-based actions and selecting those suitable for the implementation of social policies developed at national level. However, urban planners working with local authorities in the Region face political, managerial, financial and technical limitations for adequately conducting this task. Of particular interest to this paper are the limited options they have for technically assessing the impact that territorially-based actions have on reducing inequality, and therefore poverty.An operational methodology is proposed in this paper, as a step forward to enable planners to simulate, assess and monitor the impact of territorially-based actions on inequality, and to promote the use of evidence from statistical data when proposing, implementing and monitoring those actions. The methodology is introduced by inscribing it in the context of urban spatial planning, presenting the concepts that underpin it, describing how it is intended to work, and illustrating its use through the presentation of an empirical study.     

煤燃烧过程中氮氧化合物的生成及排放控制

针对煤燃烧过程中排放的氮氧化物 ( NOx)对大气造成的污染情况 ,讨论了煤燃烧过程中 NOx 的生成机理 ,简要介绍了目前燃煤过程中 NOx 排放的控制技术 ,指出了燃煤在工业应用中存在的问题及解决对策 .     

"十五"后期中国通货紧缩运行的国情特色及治理对策

我国自1997年开始出现通货紧缩现象,至今,通货紧缩的压力尚未得到根本解除。中国目前的通货紧缩与西方发达国家在成熟市场经济条件下出现的通货紧缩相比,既具有通货紧缩的一般特征,更具有中国的国情特色。在中国通货紧缩的治理上,必须采取结构性的减税措施。     

国有股减持的法律反思

国有股减持是证券市场上的焦点问题之一。2001年6月,减持方案正式出台,但其制定的初衷与实施效果大相径庭:股市应声暴跌,股民损失惨重。其根本症结在于此次国有股减持缺乏法律依据,与我国现行法律有诸多冲突之处。因此我们应正视此次国有股减持方案的缺陷,从法律角度审视国有股减持问题,以先立法后减持的方式来保障国有股成功减持。