Diffusion in homicide: Exploring a general method for detecting spatial diffusion processes
Diffusion in homicide: Exploring a general method for detecting spatial diffusion processes
复制标题
DOI：
10.1023/a:1007596225550
复制
发表时间：
1999-12-01
影响因子：
3.6
通讯作者：
Tita, G
中科院分区：
文献类型：
--
作者：
Cohen, J;Tita, G
本文提出了一种考察现象空间分布动态变化的新方法。最近引入的探索性空间数据分析（ESDA）技术为社会科学家提供了一套新的工具来区分事件的随机和非随机空间模式（Anselin, 1998）。然而，现有的ESDA度量是静态的，不允许比较同一空间内不同时间段的事件分布。一种ESDA方法- Moran散点图-具有特殊的启发式价值，因为它可以直观地显示每个空间单元与其邻居之间的局部空间关系。我们扩展了事件空间分布的静态横截面视图，以考虑空间依赖关系随时间变化的动态特征。该方法区分了相邻单位之间的传染扩散和通过共同影响广泛传播的分层扩散。我们将该方法应用于凶杀案数据，寻找城市中青少年帮派凶杀案在不同街区间的空间扩散证据。邻近人口普查区之间的传染性扩散，只有在凶杀案总数增长达到高峰的年份才会很明显，因为当地青年帮派凶杀案的高发率紧随其后的是邻近青年帮派凶杀案的显著上升。这种模式与杀人案从帮派青年到非帮派青年的传播是一致的。否则，青年帮派和青年非帮派杀人案件的增加通常同时发生在非邻近地区。
This article proposes a new method for examining dynamic changes in the spatial distribution of a phenomenon. Recently introduced exploratory spatial data analysis (ESDA) techniques provide social scientists with a new set of tools for distinguishing between random and nonrandom spatial patterns of events (Anselin, 1998). Existing ESDA measures, however, are static and do not permit comparisons of distributions of events in the same space but across different time periods. One ESDA method-the Moran scatterplot-has special heuristic value because it visually displays local spatial relationships between each spatial unit and its neighbors. We extend this static cross-sectional view of the spatial distribution of events to consider dynamic features of changes over time in spatial dependencies. The method distinguishes between contagious diffusion between adjoining units and hierarchical diffusion that spreads broadly through commonly shared influences. We apply the method to homicide data,:looking for evidence of spatial diffusion of youth-gang homicides across neighborhoods in a city. Contagious diffusion between neighboring census tracts is evident only during the year of peak growth in total homicides, when high local rates of youth-gang homicides are followed by significant increases in neighboring youth-nongang rates. This pattern is consistent with a spread of homicides from gang youth to nongang youth. Otherwise, the increases in both youth-gang and youth-nongang homicides generally occur simultaneously in nonneighboring tracts.