A weighted spatial median for clustered data

A weighted spatial median is proposed for the multivariate one-sample location problem with clustered data. Its limiting distribution is derived under mild conditions (no moment assumptions) and it is shown to be multivariate normal. Asymptotic as well as finite sample efficiencies and breakdown properties are considered, and the theoretical results are supplied with illustrative examples. It turns out that there is a potential for meaningful gains in estimation efficiency: the weighted spatial median has superior efficiency to the unweighted spatial median particularly when the cluster sizes are widely disparate and in the presence of strong intracluster correlation. The unweighted spatial median for clustered data was considered earlier by Nevalainen et al. (Can J Statist, in press, 2007). The proposed weighted estimators provide companion estimates to the weighted affine invariant sign test proposed recently by Larocque et al. (Biometrika, in press, 2007). An affine equivariant weighted spatial median is discussed in parallel.     

Modelling count data with overdispersion and spatial effects

In this paper we consider regression models for count data allowing for overdispersion in a Bayesian framework. We account for unobserved heterogeneity in the data in two ways. On the one hand, we consider more flexible models than a common Poisson model allowing for overdispersion in different ways. In particular, the negative binomial and the generalized Poisson (GP) distribution are addressed where overdispersion is modelled by an additional model parameter. Further, zero-inflated models in which overdispersion is assumed to be caused by an excessive number of zeros are discussed. On the other hand, extra spatial variability in the data is taken into account by adding correlated spatial random effects to the models. This approach allows for an underlying spatial dependency structure which is modelled using a conditional autoregressive prior based on Pettitt et al. in Stat Comput 12(4):353–367, (2002). In an application the presented models are used to analyse the number of invasive meningococcal disease cases in Germany in the year 2004. Models are compared according to the deviance information criterion (DIC) suggested by Spiegelhalter et al. in J R Stat Soc B64(4):583–640, (2002) and using proper scoring rules, see for example Gneiting and Raftery in Technical Report no. 463, University of Washington, (2004). We observe a rather high degree of overdispersion in the data which is captured best by the GP model when spatial effects are neglected. While the addition of spatial effects to the models allowing for overdispersion gives no or only little improvement, spatial Poisson models with spatially correlated or uncorrelated random effects are to be preferred over all other models according to the considered criteria.     

Spatial structure in a shift-share decomposition: new results for the Italian industrial districts case

In a previous work, a spatial shift-share model was proposed. That model took into account both the activity information of the territory and the legal status of the enterprises working inside it. The model presented, which had a twofold form, developed and came together into a unique formulation. The present proposal is able to suitably catch the neighborhood’s effect on the variation of an economical variable measured on the examined territory. This paper does not intend to repropose the aspects regarding the theoretical evolution of the first model. Instead, the principal goal is to make a comparison ceteris paribus between the results obtained with the new model and those reached through the application of the previous one, so to highlight the role of the association between the two factors included inside the decomposition. Italian industrial districts represent the economical context for this application since each model proposed is applicable to each district case without modifying the theoretical structure which is related, to the neighborhood definition. The application proposed here focuses on data on the chair industrial district located in the border region Friuli Venezia Giulia, with reference to the entire period 2000–2004.     

林下植被对祥云新松叶蜂结茧空间格局的影响

在树冠投影及其各层次和方向上,植被丰富林地的茧的聚集强度大于不丰富林地。树间,植被丰富林地茧的个体群中大个体群分布的面积小于植被不丰富林地,为20株云南松约40m~2,植被不丰富林地为30株云南松约60m~2。植被丰富林地的相对茧口密度低于不丰富林地,主要集中在 m-σ与 m 之间,占46.88%。     

BLUP in the panel regression model with spatially and serially correlated error components

Received: April 3, 2000; revised version: November 6, 2000     

古汉语虚词研究的奠基之作——《词诠》平议

现代语法名著《词诠》作为我国第一部具有系统语法体系的虚词研究著作,在学术界产生过巨大而深远的影响。此书擘划了汉语虚词研究的崭新天地,对后来汉语虚词的研究和辞书编纂影响至巨。本文对其在词语收列与诠释等方面的特色与得失作了全面的分析,以期时当今的语文性词典,尤其是汉语虚词词典的编纂提供某种借鉴和启示。     

环境心理学视域下的佛寺建筑布局——以中国汉传佛寺为例

环境心理学主要研究环境（包括自然环境和社会环境）与人的心理状态、思维活动及生产行为等之间的关系。人是环境的一部分，环境决定论、相互作用论和相互渗透论分别解释了人的心理与环境的关系。佛寺选址、佛殿布局和佛像布局的最终意义是为了烘托出佛的威力，使佛在信奉者心中具有高大、威严、慈悲的形象。对信奉者而言，佛寺的一切布局都是外在于他的环境因素，这个外在的环境结合文化因素组成特定的心理场从而影响信奉者的心理和行为；而对佛寺选址、佛殿布局和佛像布局而言，同样也受到建造者社会文化心理与行为的影响。佛寺建筑布局体现出人的心理与环境关系的复杂性。     

k-Step shape estimators based on spatial signs and ranks

In this paper, the shape matrix estimators based on spatial sign and rank vectors are considered. The estimators considered here are slight modifications of the estimators introduced in Dümbgen (1998) and Oja and Randles (2004) and further studied for example in Sirkiä et al. (2009). The shape estimators are computed using pairwise differences of the observed data, therefore there is no need to estimate the location center of the data. When the estimator is based on signs, the use of differences also implies that the estimators have the so called independence property if the estimator, that is used as an initial estimator, has it. The influence functions and limiting distributions of the estimators are derived at the multivariate elliptical case. The estimators are shown to be highly efficient in the multinormal case, and for heavy-tailed distributions they outperform the shape estimator based on sample covariance matrix.     

实现计算机藏文快速输入的关键问题研究

通过对藏文文法的深入分析研究,利用藏文字符在藏文文法上的排斥性,在通用计算机键盘键有限的键位上合理安排了所有基本藏文字符,并结合藏文字符字频统计、计算机键盘布局理论以及藏文字母与英文字母在发音上的近似性,设计了无重码藏文输入法键盘键位布局,解决了在不使用上档键和冗余键的情况下实现计算机藏文快速输入的难题;通过对藏文编码标准的分析研究,实现了基于《信息技术信息交换用藏文编码字符集基本集》和《信息技术藏文编码字符集扩充集A(B)》国际/国家标准的快速藏文输入法。     

中国地方政府的财政支出与财政效率竞争

 现有文献大都讨论地方政府之间的财政支出竞争，而忽视了它们之间的财政效率竞争，以及两者之间竞争模式的差异。本文首先使用数据包络法测算了我国209个地级市的财政效率，然后运用空间计量模型对比分析了财政支出和财政效率的空间竞争模式。结果发现，地方政府的财政支出和财政效率都存在竞争，但是两者的竞争模式截然不同。总体上，地方政府在财政支出竞争中采用直接竞争模式，而财政效率竞争表现为间接竞争模式，本文对此现象做出了解释。为了提到政府的财政效率，需要确保“用脚投票”机制产生作用，并将财政效率纳入考核标准，促使地方官员不能忽视财政效率的空间对比。