Estimation of noncentrality parameters

We propose some estimators of noncentrality parameters which improve upon usual unbiased estimators under quadratic loss. The distributions we consider are the noncentral chi-square and the noncentral F. However, we give more general results for the family of elliptically contoured distributions and propose a robust dominating estimator.     

论"革命文学"的流行性艺术素质

“革命文学”之所以在1920年代后期广为流行,其中一个重要原因,就在于它采用了为广大读者熟悉并喜爱的艺术手法,从而使其艺术素质隐含着一定的流行态势。“革命文学”的独特叙事方式,缩短了读者与作家及作品人物之间的距离,增加了叙事的真实性与感染力。而它在题材上呈现出的“故事类型”化特点,以及局部细节描写上的“套式”形态,都便于读者的理解与接受。此外,传统的人物描写手法以及语言的简单易懂,又进一步促进了“革命文学”的广泛流行。     

论医学模式的演变与医务社会工作概念的发展

医务社会工作是社会工作的一个重要的实务领域,自诞生之日起,其内涵就始终在不断的发展与丰富.医务社会工作的发展不仅受到经济社会发展的影响,更受到了医学模式发展的深切影响.本文主要对医学模式的演变与医务社会工作发展之间的关系进行了分析,认为医学模式由传统向现代模式的转变,使医务社会工作的内涵得以深化,理念得以提升.     

Averaging Lorenz curves

A large number of functional forms has been suggested in the literature for estimating Lorenz curves that describe the relationship between income and population shares. The traditional way of overcoming functional-form uncertainty when estimating a Lorenz curve is to choose the function that best fits the data in some sense. In this paper we describe an alternative approach for accommodating functional-form uncertainty, namely, how to use Bayesian model averaging to average the alternative functional forms. In this averaging process, the different Lorenz curves are weighted by their posterior probabilities of being correct. Unlike a strategy of picking the best-fitting function, Bayesian model averaging gives posterior standard deviations that reflect the functional-form uncertainty. Building on our earlier work (Chotikapanich and Griffiths, 2002), we construct likelihood functions using the Dirichlet distribution and estimate a number of Lorenz functions for Australian income units. Prior information is formulated in terms of the Gini coefficient and the income shares of the poorest 10% and poorest 90% of the population. Posterior density functions for these quantities are derived for each Lorenz function and are averaged over all the Lorenz functions.     

任务型模式在英语教学中的探索

笔者在英语教学中采用任务型教学模式的具体实践,在初中英语教育中设计了三种类型的任务,1、与生活相关的任务2、学以致用的任务3、综合性展示的任务,以上任务源于教材,达到学以致用的目的,从而促进学生全面发展。     

建设和谐社会的政府管理维度

构建和谐社会是政府管理的重要目标。在这一目标指引下中国政府必须树立“顾客至上”的管理理念,不断健全社会管理体制和公共服务体制;完善公共政策决策体制,有效调节社会各阶层的权力与利益;构建政府为主导、公民社会、非政府组织共同参与的互动协调的治理模式。实现政府、市场、公民、非政府组织之间相互信任、相互依赖、相互协调、相互作用、相互制衡的和谐的理想社会状态。     

Generalized additive models for location, scale and shape

Summary.  A general class of statistical models for a univariate response variable is presented which we call the generalized additive model for location, scale and shape (GAMLSS). The model assumes independent observations of the response variable y given the parameters, the explanatory variables and the values of the random effects. The distribution for the response variable in the GAMLSS can be selected from a very general family of distributions including highly skew or kurtotic continuous and discrete distributions. The systematic part of the model is expanded to allow modelling not only of the mean (or location) but also of the other parameters of the distribution of y , as parametric and/or additive nonparametric (smooth) functions of explanatory variables and/or random-effects terms. Maximum (penalized) likelihood estimation is used to fit the (non)parametric models. A Newton–Raphson or Fisher scoring algorithm is used to maximize the (penalized) likelihood. The additive terms in the model are fitted by using a backfitting algorithm. Censored data are easily incorporated into the framework. Five data sets from different fields of application are analysed to emphasize the generality of the GAMLSS class of models.     

Bayesian analysis of a marked point process: Application in seismic hazard assessment

Point processes are the stochastic models most suitable for describing physical phenomena that appear at irregularly spaced times, such as the earthquakes. These processes are uniquely characterized by their conditional intensity, that is, by the probability that an event will occur in the infinitesimal interval (t, t+Δt), given the history of the process up tot. The seismic phenomenon displays different behaviours on different time and size scales; in particular, the occurrence of destructive shocks over some centuries in a seismogenic region may be explained by the elastic rebound theory. This theory has inspired the so-called stress release models: their conditional intensity translates the idea that an earthquake produces a sudden decrease in the amount of strain accumulated gradually over time along a fault, and the subsequent event occurs when the stress exceeds the strength of the medium. This study has a double objective: the formulation of these models in the Bayesian framework, and the assignment to each event of a mark, that is its magnitude, modelled through a distribution that depends at timet on the stress level accumulated up to that instant. The resulting parameter space is constrained and dependent on the data, complicating Bayesian computation and analysis. We have resorted to Monte Carlo methods to solve these problems.     

Real nonparametric regression using complex wavelets

Summary.  Wavelet shrinkage is an effective nonparametric regression technique, especially when the underlying curve has irregular features such as spikes or discontinuities. The basic idea is simple: take the discrete wavelet transform of data consisting of a signal corrupted by noise; shrink or remove the wavelet coefficients to remove the noise; then invert the discrete wavelet transform to form an estimate of the true underlying curve. Various researchers have proposed increasingly sophisticated methods of doing this by using real-valued wavelets. Complex-valued wavelets exist but are rarely used. We propose two new complex-valued wavelet shrinkage techniques: one based on multiwavelet style shrinkage and the other using Bayesian methods. Extensive simulations show that our methods almost always give significantly more accurate estimates than methods based on real-valued wavelets. Further, our multiwavelet style shrinkage method is both simpler and dramatically faster than its competitors. To understand the excellent performance of this method we present a new risk bound on its hard thresholded coefficients.     

国有企业的特殊性与我国国有企业的布局定位

国有企业特殊性的真实内涵表现为,它有着特殊的所有者和所有者代表、特殊的社会目标、特殊的社会经济功能和特殊的产权组织运作机制。因此,越是在以社会目标为主的产业领域,国有企业就越有存在的价值。尽管国有企业的布局是一种趋向性和开放式的动态布局,但它所传递的信息表明国有企业会在特殊产业领域中以合适的方式继续存在并扮演重要角色。