Testing for ordered failure rates under general progressive censoring

For exponentially distributed failure times under general progressive censoring schemes, testing procedures for ordered failure rates are proposed using the likelihood ratio principle. Constrained maximum likelihood estimators of the failure rates are found. The asymptotic distributions of the test statistics are shown to be mixtures of chi-square distributions. When testing the equality of the failure rates, a simulation study shows that the proposed test with restricted alternative has improved power over the usual chi-square statistic with an unrestricted alternative. The proposed methods are illustrated using data of survival times of patients with squamous carcinoma of the oropharynx.     

The changing spatial distribution and concentration of Australias chinese and Vietnamese communities: An analysis of 1986–2006 Australian population census data

This paper describes the changing spatial distribution and concentration of Chinese and Vietnamese communities in Australia over the two past decades. The research analyses data of individuals (i) born in the People’s Republic of China or Vietnam, (ii) of Chinese or Vietnamese ancestry, and (iii) who spoke Chinese or Vietnamese languages at home. Basic demographic and economic factors at the SLA level are considered to provide an initial discussion of meso-level factors which may have contributed to changes in Chinese-and Vietnamese-Australian distributions and concentrations since 1986. As expected, from field observations, the data reveal a contrasting picture of the spatial distribution and concentration of the Chinese- and Vietnamese-Australian communities, and indicate that although a few areas of high Vietnamese spatial concentration have persisted into 2006, and a few areas of high’ Chinese spatial concentration have developed since 1986, overall there is an increasing dispersion of both communities into the broader Australian community.     

Why a time effect often has a limited impact on capture‐recapture estimates in closed populations

The author is concerned with log‐linear estimators of the size N of a population in a capture‐recapture experiment featuring heterogeneity in the individual capture probabilities and a time effect. He also considers models where the first capture influences the probability of subsequent captures. He derives several results from a new inequality associated with a dispersive ordering for discrete random variables. He shows that in a log‐linear model with inter‐individual heterogeneity, the estimator N is an increasing function of the heterogeneity parameter. He also shows that the inclusion of a time effect in the capture probabilities decreases N in models without heterogeneity. He further argues that a model featuring heterogeneity can accommodate a time effect through a small change in the heterogeneity parameter. He demonstrates these results using an inequality for the estimators of the heterogeneity parameters and illustrates them in a Monte Carlo experiment     

全局主成分法在土地集约利用评价中应用——以中部地区为例

在构建评价指标体系基础上,运用基于三维立体时序全局表的全局主成分法对1997￣2005年东部、中部、西部、东北地区原始数据进行分析,对比分析得出中国中部地区的土地集约利用水平变化规律。结果表明:全局主成分法的适用性广;近9年来中部地区土地集约利用水平在不断提高;中部地区土地集约利用水平与东部和西部、东北地区比较呈现两极变化趋势。     

Simulation of right and left truncated gamma distributions by mixtures

We study the properties of truncated gamma distributions and we derive simulation algorithms which dominate the standard algorithms for these distributions. For the right truncated gamma distribution, an optimal accept–reject algorithm is based on the fact that its density can be expressed as an infinite mixture of beta distribution. For integer values of the parameters, the density of the left truncated distributions can be rewritten as a mixture which can be easily generated. We give an optimal accept–reject algorithm for the other values of the parameter. We compare the efficiency of our algorithm with the previous method and show the improvement in terms of minimum acceptance probability. The algorithm proposed here has an acceptance probability which is superior to e/4.     

LDPC编码的最优化HARQ方案研究

使用高斯近似和最优化理论的方法,对基于LDPC码度分布的混合自动重发请求(HARQ)方案的性能进行了研究。研究表明,根据LDPC编码的度分布和初始信道条件,能够确定一个编码码字中各个度数的比特所对应的最优的重发比例,如果按照该比例进行重发,重发功率的效率能够最大化。计算结果显示基于LDPC码度分布的混合自动重发请求方案具有最优的重发比例,是一种最优化方案。     

中卫型集群结构的运行绩效及对辽宁装备制造业的启示

本文从中卫型集群内企业的行为分析出发,通过集群内企业采取的不同行为对集群结构进行分类,从微观角度对其运行绩效进行了定性分析。在中卫型产业集群中,集群内部合作增强集群的竞争优势。集群整体的竞争优势的增强取决于核心企业是否在行业中具有绝对优势。并结合辽宁装备制造业的实际,提出了做优做强辽宁装备制造业龙头企业的意义及有效途径。     

概率论在极限问题中的应用

通过建立概率模型、利用概率论相关定理解决了复杂的求极限问题。     

Bayesian point null hypothesis testing via the posterior likelihood ratio

This paper gives an exposition of the use of the posterior likelihood ratio for testing point null hypotheses in a fully Bayesian framework. Connections between the frequentist P-value and the posterior distribution of the likelihood ratio are used to interpret and calibrate P-values in a Bayesian context, and examples are given to show the use of simple posterior simulation methods to provide Bayesian tests of common hypotheses.     

Shortage of girls in China today

China has the most severe shortage of girls compared to boys of any country in the world today, as documented by China's surveys and censuses up to 2000. This article evaluates data on sex ratios in China since before the founding of the People's Republic, and shows that the relative dearth of girls has become more extreme during the last two decades, and that the problem is real and not merely due to undercounting of girls. Daughters are lost primarily through sex-selective abortion, secondly through excess female infant mortality, and thirdly through neglect or mistreatment of girls up to age three, in cities as well as rural areas. Until recently, the dearth of girls was confined to second or higher-order births, but now couples in some provinces are using sex-selective abortions for first births. Maps show the geographical concentration of life-threatening discrimination against girls and its spread over time. Son preference, low fertility and technology combine to cause the loss of daughters in China today and compulsory family planning and the one-child policy exacerbate the problem. The discussion includes what the People's Republic of China has done to ameliorate life-threatening discrimination against girls and what further steps might be taken to improve the situation.