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81.
82.
83.
Multicollinearity and correlation among local regression coefficients in geographically weighted regression 总被引:5,自引:3,他引:5
Present methodological research on geographically weighted regression (GWR) focuses primarily on extensions of the basic GWR model, while ignoring well-established diagnostics tests commonly used in standard global regression analysis. This paper investigates multicollinearity issues surrounding the local GWR coefficients at a single location and the overall correlation between GWR coefficients associated with two different exogenous variables. Results indicate that the local regression coefficients are potentially collinear even if the underlying exogenous variables in the data generating process are uncorrelated. Based on these findings, applied GWR research should practice caution in substantively interpreting the spatial patterns of local GWR coefficients. An empirical disease-mapping example is used to motivate the GWR multicollinearity problem. Controlled experiments are performed to systematically explore coefficient dependency issues in GWR. These experiments specify global models that use eigenvectors from a spatial link matrix as exogenous variables.This study was supported by grant number 1 R1 CA95982-01, Geographic-Based Research in Cancer Control and Epidermiology, from the National Cancer Institute. The author thank the anonymous reviewers and the editor for their helpful comments. 相似文献
84.
长江三角洲地区水和热通量的时空变化特征及影响因子 总被引:9,自引:2,他引:9
文中利用改进的K B模式和牛顿扩散方法及 196 1年以来的长江三角洲 (2 8~ 33°N ,118~ 12 3°E)地区的 4 8个测站的常规气象资料 ,估计了该地区近 4 0a来的蒸散量和感热通量。结合该地区的气温、太阳辐射等气候资料和 196 0年以来该区域土地资源利用变化等有关信息对该地区的潜热通量和感热通量的时 空间变化特征及其可能成因进行了综合分析。结果认为该地区自 2 0世纪 70年代开始平均蒸散量有逐渐减小的趋势 ,与 1980年相比 ,1998年区域年平均蒸散量减小了 2 4mm。区域平均感热通量与蒸散量相比在此期间变化并不明显。通过对该地区的云量、太阳辐射及土地利用变化资料分析认为 ,造成该地区平均蒸散量减少趋势的的原因之一是用于蒸发的能量即太阳辐射的减少 ,而造成太阳辐射减少的可能原因为云量及大气透明度的变化所至 ;原因之二是该地区地表覆盖条件的改变。近 2 0a来 ,该地区的水田、旱地及水域面积占总面积的比率分别减少 1.35 3% ,4 .4 4 2 %和2 .5 97% ,而城镇建设、工矿及其它建设用地面积则增加 3.345 %。耕地及水面的减小和城镇及建设用地面积的增加从整体上使区域平均蒸发量减少。 相似文献
85.
西藏地区旱涝等级划分及时空分布特征 总被引:7,自引:3,他引:7
利用西藏22个站点1969-1998年逐日降水资料,采用d指数旱涝等级方法。按夏季(5-9月),初夏(5-6月),盛夏(7-8月)时段进行了旱涝等级划分。采用EOF分析方法对全区22个站点旱涝等级展开分解,得出西藏地区的旱涝时空分布特征,主要类型和周期,而且对西藏地区夏季(5-9月)的旱涝做了预测。 相似文献
86.
The political turning point in the former GDR and the transformation processes that have been observed since then have significantly
affected economic and social structures in the new Federal States. Gender roles, however, were subjected to even more dramatic
changes. Whilst many women experienced the employment policies of the GDR era as beneficial, social researchers often designate
them as the losers of unification nowadays. This is largely because the abundance of State support measures for employed women
and mothers has been drastically reduced and women as a group have been hit hardest by the crisis on the East German labour
market. Using two cases (Mecklenburg-Westpommerania and Thuringia), this paper aims to illustrate the impact of the transformation
process on the everyday (working) lives of women. We are particularly concerned with a comparative analysis of how women experience
and deal with regional disparities in East Germany.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
87.
Drought in Bulgaria is analyzed from the multiple viewpoints of statistical occurrence, spatial patterns, and synoptic conditions.
A new index of drought, the SD (spatial-dryness) index, characterizes drought by both intensity and spatial extent. The occurrence of the SD index is analyzed using global
gridded data sets. Examination of transitional probabilities of multiple months and years with drought occurrence suggests
persistence is sufficiently frequent to be important for climate-related environmental planning. Finally, it is shown that
specific seasonal synoptic patterns are associated with wet and dry conditions in Bulgaria.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
88.
It is critical to understand and quantify the temporal and spatial variability in hillslope hydrological data in order to advance hillslope hydrological studies, evaluate distributed parameter hydrological models, analyse variability in hydrological response of slopes and design efficient field data sampling networks. The spatial and temporal variability of field‐measured pore‐water pressures in three residual soil slopes in Singapore was investigated using geostatistical methods. Parameters of the semivariograms, namely the range, sill and nugget effect, revealed interesting insights into the spatial structure of the temporal situation of pore‐water pressures in the slopes. While informative, mean estimates have been shown to be inadequate for modelling purposes, indicator semivariograms together with mean prediction by kriging provide a better form of model input. Results also indicate that significant temporal and spatial variability in pore‐water pressures exists in the slope profile and thereby induces variability in hydrological response of the slope. Spatial and temporal variability in pore‐water pressure decreases with increasing soil depth. The variability decreases during wet conditions as the slope approaches near saturation and the variability increases with high matric suction development following rainfall periods. Variability in pore‐water pressures is greatest at shallow depths and near the slope crest and is strongly influenced by the combined action of microclimate, vegetation and soil properties. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
89.
90.
基于DEM的分布式水文模型构建方法 总被引:52,自引:4,他引:52
基于 DEM的分布式水文模型是现代水文学同高科技 (如计算机技术、 3S技术等 )相结合的产物 ,是研究变化环境下水文循环与水资源演化规律的理想工具 ,代表了水文模型的最新发展方向。从 DEM的特性出发 ,本文探讨并总结了分布式水文模型的特点、建模思路和模型基本结构框图。在流域离散化方面 ,重点介绍了分布式水文模型常用的三种单元划分方法 ;最后 ,针对分布式水文模型构建问题 ,从“输入模块”、“单元水文模型”、“河网汇流模型”三方面 ,阐述了分布式水文模型微结构构建方法。 相似文献