网络空间语言互动变异的经济效能与损蚀

网络空间的交际用语是把双刃剑,多形态的语言带来了网络交际的便捷,但也为语言系统本身和思想情感交流带来诸多困扰。文章基于网络空间交际用语的基本形态,认为语言在网络空间交际互动中体现出多重经济效能,语言趋简是以较小的语言资源投入实现最佳的交互目的;语言趋快是为了减少交际的时间成本;语言趋新是为了获取交际关注与群体认同。因获取语言经济效能而对汉语系统、言语交际以及语言生态文明等带来了一定的损蚀。     

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.     

Exact average coverage probabilities and confidence coefficients of confidence intervals for discrete distributions

For a confidence interval (L(X),U(X)) of a parameter θ in one-parameter discrete distributions, the coverage probability is a variable function of θ. The confidence coefficient is the infimum of the coverage probabilities, inf  _θ P _θ (θ∈(L(X),U(X))). Since we do not know which point in the parameter space the infimum coverage probability occurs at, the exact confidence coefficients are unknown. Beside confidence coefficients, evaluation of a confidence intervals can be based on the average coverage probability. Usually, the exact average probability is also unknown and it was approximated by taking the mean of the coverage probabilities at some randomly chosen points in the parameter space. In this article, methodologies for computing the exact average coverage probabilities as well as the exact confidence coefficients of confidence intervals for one-parameter discrete distributions are proposed. With these methodologies, both exact values can be derived.     

贫困测量中恩格尔系数的失效及分析

 恩格尔系数在我国的适用性问题是学术界重要议题之一。本文利用对哈尔滨市和沈阳市贫困人口的调查数据,分析了恩格尔系数在我国城市贫困测量中失效的问题及原因。研究者尝试对恩格尔系数的分子、分母进行了重新界定和适当的修正,研究检验表明,从宏观测量和微观测量两个方面,修正恩格尔系数都能更准确的反映我国城市贫困家庭的真实生活水平。     

变数额标准为人员标准——农村低保标准确定的范式转换

中国扶贫和发展的情况表明,要解决农村全部贫困人员的温饱问题必须建立农村低保制度。受扶贫和城市低保对像确认的影响,我国实行农村低保试点的地区多采取数额标准作为确定农村低保对象的主要确认方法。鉴于数额标准在确定农村低保对象中的种种缺陷和弊端,文章在分析农村低保意义的基础上论证了变数额标准为人员标准在农村低保对象确认中的意义、作用、应注意的问题和确认的方法。     

人类在景观发育中的作用

本文通过对人类影响景观发育的思想、行为、方法和影响结果的分析,在理论上论证了人类对景观发育影响的显著性,引申到按照人类对景观影响的结果--景观变化梯度过于剧烈的话,景观系统将走向崩溃,进而提出人类对景观发育控制理念构建人-地协调的景观系统.     

应用同伦正则化算法反演二维溶质运移模型中的弥散系数

利用同伦正则化算法探讨了二维对流弥散方程的依赖空间变量的弥散系数反演问题.讨论了初始迭代值、数值微分步长、以及收敛精度对算法实现的影响.数值模拟表明,同伦正则化算法对于此类参数反演问题是一种有效的方法.     

Some novel results on pairwise quasi-asymptotical independence with applications to risk theory

In this article we obtain some novel results on pairwise quasi-asymptotically independent (pQAI) random variables. Concretely speaking, let X₁, …, X_n be n real-valued pQAI random variables, and W₁, …, W_n be another n non negative and arbitrarily dependent random variables, but independent of X₁, …, X_n. Under some mild conditions, we prove that W₁X₁, …, W_nX_n are still pQAI as well. Our result is in a general setting whether the primary random variables X₁, …, X_n are heavy-tailed or not. Finally, a special case of above result is applied to risk theory for investigating the finite-time ruin probability for a discrete-time risk model with a wide type of dependence structure.     

Approximate confidence intervals for the weighted kappa coefficient of a binary diagnostic test subject to a case–control design

Case–control design to assess the accuracy of a binary diagnostic test (BDT) is very frequent in clinical practice. This design consists of applying the diagnostic test to all of the individuals in a sample of those who have the disease and in another sample of those who do not have the disease. The sensitivity of the diagnostic test is estimated from the case sample and the specificity is estimated from the control sample. Another parameter which is used to assess the performance of a BDT is the weighted kappa coefficient. The weighted kappa coefficient depends on the sensitivity and specificity of the diagnostic test, on the disease prevalence and on the weighting index. In this article, confidence intervals are studied for the weighted kappa coefficient subject to a case–control design and a method is proposed to calculate the sample sizes to estimate this parameter. The results obtained were applied to a real example.     

Unified Inference for Sparse and Dense Longitudinal Data in Time‐varying Coefficient Models

Time‐varying coefficient models are widely used in longitudinal data analysis. These models allow the effects of predictors on response to vary over time. In this article, we consider a mixed‐effects time‐varying coefficient model to account for the within subject correlation for longitudinal data. We show that when kernel smoothing is used to estimate the smooth functions in time‐varying coefficient models for sparse or dense longitudinal data, the asymptotic results of these two situations are essentially different. Therefore, a subjective choice between the sparse and dense cases might lead to erroneous conclusions for statistical inference. In order to solve this problem, we establish a unified self‐normalized central limit theorem, based on which a unified inference is proposed without deciding whether the data are sparse or dense. The effectiveness of the proposed unified inference is demonstrated through a simulation study and an analysis of Baltimore MACS data.