A multivariate zero-inflated binomial model for the analysis of correlated proportional data

In this paper, a new multivariate zero-inflated binomial (MZIB) distribution is proposed to analyse the correlated proportional data with excessive zeros. The distributional properties of purposed model are studied. The Fisher scoring algorithm and EM algorithm are given for the computation of estimates of parameters in the proposed MZIB model with/without covariates. The score tests and the likelihood ratio tests are derived for assessing both the zero-inflation and the equality of multiple binomial probabilities in correlated proportional data. A limited simulation study is performed to evaluate the performance of derived EM algorithms for the estimation of parameters in the model with/without covariates and to compare the nominal levels and powers of both score tests and likelihood ratio tests. The whitefly data is used to illustrate the proposed methodologies.     

山村支教志愿者的故事

这里有点像电影《凤凰琴》中的学校,3个教室,5个老师,62个学生分成三个年级(隔年一招生),铁炉子放在每个教室的中间,尽量让它的热量均匀地散发给每一个孩子。校园中除了教室的那排小白房,有三个较高的“建筑物”,一个被风雨侵蚀得裂纹纵     

东北亚的马蹄声

他们身骑战马呼啸而来,一路厮杀,占据了东北亚地区的中心地带,开创了东晋十六国前燕、后燕和北燕近一个世纪的辉煌。     

美国家庭资产统计方法和分析

一、引言家庭资产是指家庭拥有或控制的能以货币计量的经济形态,家庭资产由实物资产和金融资产两部分组成,包括各种家庭资产、家庭债权债务和其它权利。家庭资产反映了居民的生活水平,也是衡量国家经济实力的主要依据之一。学者们发现,居民通过家庭资产结构合理化,能够实现跨时间的消费效用最大化(Kelley,1953,Feinberg,1964)。另外,税收制度与家庭资产结构之间存在着关联关系(Bergstresser,2004)。对于一个具体的家庭来说,家庭资产、收入和消费是一个整体性的经济概念,家庭资产的数量和结构,将直接影响个人和家庭的消费形式和数量,进而影…     

Nonparametric Tests for Stratum Effects in the Cox Model

Thispaper considers the stratified proportional hazards model witha focus on the assessment of stratum effects. The assessmentof such effects is often of interest, for example, in clinicaltrials. In this case, two relevant tests are the test of stratuminteraction with covariates and the test of stratum interactionwith baseline hazard functions. For the test of stratum interactionwith covariates, one can use the partial likelihood method (Kalbfleischand Prentice, 1980; Lin, 1994). For the test of stratum interactionwith baseline hazard functions, however, there seems to be noformal test available. We consider this problem and propose aclass of nonparametric tests. The asymptotic distributions ofthe tests are derived using the martingale theory. The proposedtests can also be used for survival comparisons which need tobe adjusted for covariate effects. The method is illustratedwith data from a lung cancer clinical trial.     

Designing and integrating composite networks for monitoring multivariate gaussian pollution fields

Networks of ambient monitoring stations are used to monitor environmental pollution fields such as those for acid rain and air pollution. Such stations provide regular measurements of pollutant concentrations. The networks are established for a variety of purposes at various times so often several stations measuring different subsets of pollutant concentrations can be found in compact geographical regions. The problem of statistically combining these disparate information sources into a single 'network' then arises. Capitalizing on the efficiencies so achieved can then lead to the secondary problem of extending this network. The subject of this paper is a set of 31 air pollution monitoring stations in southern Ontario. Each of these regularly measures a particular subset of ionic sulphate, sulphite, nitrite and ozone. However, this subset varies from station to station. For example only two stations measure all four. Some measure just one. We describe a Bayesian framework for integrating the measurements of these stations to yield a spatial predictive distribution for unmonitored sites and unmeasured concentrations at existing stations. Furthermore we show how this network can be extended by using an entropy maximization criterion. The methods assume that the multivariate response field being measured has a joint Gaussian distribution conditional on its mean and covariance function. A conjugate prior is used for these parameters, some of its hyperparameters being fitted empirically.     

球墨铸铁曲轴的气体软氮化

柴油机的珠墨铸铁曲轴系重要零件,气体软氮化应用到球墨铸铁领域还是一种新工艺,而且比中频淬火效果好,提高了曲轴的抗疲劳和抗磨损的能力。本文对气体软氮化的基本原理、设备、工艺参数的选择和催渗方法进行了探讨,对软氮化后曲轴的尺寸形状误差、光洁度和机械性能的提高等进行了较详细的试验、分析和比较,结果,经气体软氮化后的曲轴不但尺寸形站误差符合图纸要求外,而且抛去轻微氧化层后光洁度还略有提高,曲轴安全系数由1.3～1.6提高到1.70～1.77,并且一般不再发生疲劳断(?),使用寿命比原来寿命增加3.32倍以上。     

六端口技术自校准方法解的不唯一性证明

本文就六端口技术自校准方法进行了分析讨论,用解析方法和计算机模拟方法分别证明了自校准方法解的不唯一性.从而否定了自校准方法是六端口技术最突出的优点之一这个传统概念.     

伽马分布的形状参数的一种估计

本文利用服从伽马分布的随机变量 X 与其逆 X~(-1)的协方差只与形状参数有关这一性质,给出伽马分布形状参数的所谓自逆协方差估计,进而构造了相应的无偏估计,并证明了这类估计的大样本性质:强相合性以及渐近正态性。     

我国政府统计中多层次推断问题讨论

当前,多层次推断问题已成为我国在政府统计中推广抽样调查所面临的最大难题。本文回顾了现有解决多层次推断问题的方法,指出这些方法在使用上的限制;提出从改进估计的角度解决多层次推断问题,讨论了借助辅助信息改进估计的方法和建立统计模型进行推估的方法,并指出各种方法的优劣和适用情况;简要探讨了大数据背景下对解决多层次推断问题的一些启示。