Spatial Mallows model averaging for geostatistical models

Important progress has been made with model averaging methods over the past decades. For spatial data, however, the idea of model averaging has not been applied well. This article studies model averaging methods for the spatial geostatistical linear model. A spatial Mallows criterion is developed to choose weights for the model averaging estimator. The resulting estimator can achieve asymptotic optimality in terms of L₂ loss. Simulation experiments reveal that our proposed estimator is superior to the model averaging estimator by the Mallows criterion developed for ordinary linear models [Hansen, 2007] and the model selection estimator using the corrected Akaike's information criterion, developed for geostatistical linear models [Hoeting et al., 2006]. The Canadian Journal of Statistics 47: 336–351; 2019 © 2019 Statistical Society of Canada     

我国普惠金融发展的空间动态收敛性研究

文章利用2007-2016年我国省级面板数据,在结合传统收敛模型和空间计量模型的基础上,对系统性金融风险下我国普惠金融发展的收敛性进行了对比分析。结果表明:各地区的普惠金融发展水平呈现出逐渐增长的态势,但仍存在较大的地区差异性。在全时段内普惠金融发展存在绝对β收敛以及条件β收敛现象,且β系数的绝对值呈现出波动上升的趋势。系统性金融风险指数的引入显著增加了β系数的绝对值,大大提升了普惠金融发展的收敛速度。     

托尼·莫里森近作《爱》的种族空间政治

虽然列斐伏尔的<空间的生产>忽略种族意识形态,他的"空间三一论"却体现种族空间政治张力.本论文将莫里森新作<爱>的故事空间作为观察对象,以列斐伏尔的"空间三一论"为理论框架,分析文本虚构世界的空间关系,探讨虚构社会如何为空间所结构,空间关系如何反映社会关系,权力怎样构建空间,空间怎样表征权力.指出:种族统治体现为空间统治,空间构建表达个体、社会之间的协商.科西一家的空间发展和位移、"丝镇"的空间构成和重组,折射出种族现实的变化,空间生成密码随着时代的发展而变化.     

Residual Analysis for Inhomogeneous Neyman–Scott Processes

Abstract. In this article, we introduce a residual analysis for inhomogeneous Neyman–Scott models based on Laplace functionals. Our simulation study shows that this residual analysis method has a good performance in assessing goodness‐of‐fit and revealing inadequacy of the fitted model. The method is employed in fitting a Thomas model to California redwood trees data and a Matérn model to the locations of hickory trees in Lansing woods, Michigan.     

西部地区中小城市自选型超级市场空间布局研究——以汉中市为例

通过实地调研、GIS技术手段应用以及与其他城市的对比得出：第一,大城市大型超市的空间分布一般呈分散态,而西部中小城市大型超市的空间分布则多成集中态分布;与大城市大型超市一般位于中心商务区和住宅区之间的次一级商业中心不同,西部中小城市大型超市一般位于地价最高的市级中心;而对于交通通达性和对周边市场的要求方面,在大城市与西部中小城市之间不存在本质区别。第二,在服务半径方面,大中城市中大型超市均远低于商务部的规定,大型超市在各类城市中竞争均比较激烈,新开设大超市的数量与区位选择需更加慎重。第三,在本文研究中,中等城市居民更偏好大超市购物,但中小型超市服务半径比较合理,与居住关系更为密切,成为大型超市的有益补充。     

Time series in m-dimensions definition,problems and prospects

We define time series in m dimensions x, as follows: the observed variable z depends on and similarly n time series in m variables where f(x,t) and x are vectors. This is the discrete case. The continuous case is similar. Distinction is made between m time series in zero dimension, at a particular point x, and one time series in m dimensions.     

“Birds of a Feather” Fail Together: Exploring the Nature of Dependency in SME Defaults

This article studies the effects of incorporating the interdependence among London small business defaults into a risk analysis framework using the data just before the financial crisis. We propose an extension from standard scoring models to take into account the spatial dimensions and the demographic characteristics of small and medium‐sized enterprises (SMEs), such as legal form, industry sector, and number of employees. We estimate spatial probit models using different distance matrices based only on the spatial location or on an interaction between spatial locations and demographic characteristics. We find that the interdependence or contagion component defined on spatial and demographic characteristics is significant and that it improves the ability to predict defaults of non–start‐ups in London. Furthermore, including contagion effects among SMEs alters the parameter estimates of risk determinants. The approach can be extended to other risk analysis applications where spatial risk may incorporate correlation based on other aspects.     

Fast bandwidth selection for estimation of the pair correlation function

ABSTRACT

Kernel estimation is a popular approach to estimation of the pair correlation function which is a fundamental spatial point process characteristic. Least squares cross validation was suggested by Guan [A least-squares cross-validation bandwidth selection approach in pair correlation function estimations. Statist Probab Lett. 2007;77(18):1722–1729] as a data-driven approach to select the kernel bandwidth. The method can, however, be computationally demanding for large point pattern data sets. We suggest a modified least squares cross validation approach that is asymptotically equivalent to the one proposed by Guan but is computationally much faster.     

Neither global nor local: Heterogeneous connectivity in spatial network structures of world migration

For a long time, geographic regions were considered the dominant spatial arbiter of international migration of people. However, since the late 1970s, many scholars have argued that movements reach beyond contiguous regions to connect distant, dispersed, and previously disconnected countries across the globe. The precise structure of world migration, however, remains an open question. We apply network analysis that incorporates spatial information to international migration-stock data to examine what multilateral structures of world migration have emerged from the interplay of regional concentration (local cohesion) and global interconnectedness (global cohesion) for the period 1960–2000. In the world migration network (WMN), nodes represent countries located in geographic space, and edges represent migrants from an origin country who live in a destination country during each decade. We characterize the large-scale structure and evolution of the WMN by algorithmically detecting international migration communities (i.e., sets of countries that are densely connected via migration) using a generalized modularity function for spatial, temporal, and directed networks. Our findings for the whole network suggest that movements in the WMN deviate significantly from the regional boundaries of the world and that international migration communities have become globally interconnected over time. However, we observe a strong variability in the distribution of strengths, neighborhood overlaps, and lengths of migration edges in the WMN. This manifests as three types of communities: global, local, and glocal. We find that long-distance movements in global communities bridge multiple non-contiguous countries, whereas local (and, to a lesser extent, glocal) communities remain trapped in contiguous geographic regions (or neighboring regions) for almost the whole period, contributing to a spatially fragmented WMN. Our findings demonstrate that world migration is neither regionally concentrated nor globally interconnected, but instead exhibits a heterogeneous connectivity pattern that channels unequal migration opportunities across the world.     

空间性语言、空间语法和中国古代诗歌的空间性——从言、象、意论中国古代诗学的空间性之一

文学艺术是语言的艺术,因而从语言文字的角度来探讨中国古代诗歌艺术是诗学研究的应有之义。而作为创作媒介的汉语,由于自身是种空间性语言以及其语法的空间性,则必然使得中国古代诗歌艺术具有空间性的特性。