An EM-type algorithm for multivariate mixture models

This paper introduces a new approach, based on dependent univariate GLMs, for fitting multivariate mixture models. This approach is a multivariate generalization of the method for univariate mixtures presented by Hinde (1982). Its accuracy and efficiency are compared with direct maximization of the log-likelihood. Using a simulation study, we also compare the efficiency of Monte Carlo and Gaussian quadrature methods for approximating the mixture distribution. The new approach with Gaussian quadrature outperforms the alternative methods considered. The work is motivated by the multivariate mixture models which have been proposed for modelling changes of employment states at an individual level. Similar formulations are of interest for modelling movement between other social and economic states and multivariate mixture models also occur in biostatistics and epidemiology.     

Banach空间混合列强大数定律的收敛定理

文献［１］讨论了Ｂａｎａｃｈ空间中随机变元列｛Ｘｉ｝满足一定条件时的完全收敛性。文中将进一步讨论Ｂａｎａｃｈ空间中独立非同分布随机变元列的收敛速度，得到了满意的结果     

企业技术创新风险评价的现状

企业技术创新中存在着许多风险因素,如何识别这些风险因素并对他们进行分析、预测、跟踪评价是每个企业需要解决的重要问题。通过分析企业技术创新风险的内涵和国内外企业技术创新的现状,提出了企业进行技术创新风险因素评价的意义与作用及企业技术创新风险评价的原理与思路。     

中国古代都城空间形态要素分析——以唐宋都城为例

城市形态要素的研究是城市形态特征研究的基础。中国古代都城空间形态由路径、边界、区域、节点、标志物等要素构成,它们之间有着复杂的结构关系。古代都城形态要素的空间功能和价值理念在于实现都城的政治核心功能,表达都城高度集权的政治体制和中国传统伦理与哲学思想的建设理念。都城空间形态要素的变化受政治经济、社会伦理、文化思想等因素影响,并导致都城空间形态特征的演变。     

关于当前文艺思潮的思考

我国当前构建起有着开放性空间的社会主义文艺整体架构 ,但也出现涉及历史观、价值观、审美观等带有根本性的问题。其中有 :历史与现实、内容与形式、建设与破坏、本土与异域等关系。文化艺术是特定民族和时代的形象表达 ,其中健康向上的主体精神不可迷失或削弱。     

关于平面Clipping随机场的若干性质

讨论了平面随机场关于水平 μ 的 clipping 随机场的各向同性,齐性,独立性和可分性的若干结果.     

Estimation of Human Reproductive Risk from Animal Studies: Determination of Interspecies Extrapolation Factors for Steroid Hormone Effects on the Male

The problem of extrapolating effects of reproductive toxins on experimental animals to predict the doses that would produce infertility in human males is discussed using published data on effects of testosterone and estradiol on sperm production in the rat, rabbit, rhesus monkey, ram, stallion, and humans. This analysis indicates that calculation of the dose of testosterone that reduces human sperm counts by a given percentage is best done using the dose administered to laboratory animals expressed on the basis of body weight, as opposed to some other parameter such as body surface area. A survey of the available data in the literature indicates the incompleteness of the data set and the specific information needed to improve the basis for extrapolation. Nevertheless, we can predict from studies on laboratory animals the dose of testosterone necessary to reduce sperm counts in humans within a factor of 2.     

A zero-one law for large order statistics

Fix r ≥ 1, and let {M_nr} be the rth largest of {X₁,X₂,…X_n}, where X₁,X₂,… is a sequence of i.i.d. random variables with distribution function F. It is proved that P[M_nr ≤ u_n i.o.] = 0 or 1 according as the series Σ^∞_n=3Fⁿ(u_n)(log log n)^r/n converges or diverges, for any real sequence {u_n} such that n{1 -F(u_n)} is nondecreasing and divergent. This generalizes a result of Bamdorff-Nielsen (1961) in the case r = 1.     

Some critical aspects of the use of exchangeability in statistics

Summary This expository paper provides a framework for analysing de Finetti's representation theorem for exchangeable finitely additive probabilities. Such an analysis is justified by reasoning of statistical nature, since it is shown that the abandonment of the axiom of σ-additivity has some noteworthy consequences on the common interpretation of the Bayesian paradigm. The usual (strong) fromulation of de Finetti's theorem is deduced from the finitely additive (weak) formulation, and it is used to solve the problem of stating the existence of a stochastic process, with given finite-dimensional probability distributions, whose sample paths are probability distributions. It is of importance, in particular, to specify prior distributions for nonparametric inferential problems in a Bayesian setting. Research partially supported by MPI (40% 1990, Gruppo Nazionale ?Modelli Probabilistici e Statistica Matematica?).     

高校官方微信公众号传播效果影响因素的实证研究——基于启发-系统模型

高校官方微信公众号是高校宣传形象,与学生联络情感的重要平台,对高校官微传播效果进行影响因素分析,有助于官微运营者改进推送策略,提升传播效果。文章借鉴社会心理学的启发-系统模型,采用内容分析法对7个层次42所高校的1024篇官方微信公众号文章样本进行编码分析。分层回归模型结果显示,大学生主要通过启发模式处理高校官微信息,学校名气、推送时间、文章位置、编排形式等是影响传播效果的关键因素;推送内容对传播效果作用有限,能引起情感共鸣的内容更受欢迎。