RT Article
T1 Diffusion in Homicide: Exploring a General Method for Detecting Spatial Diffusion Processes
JF Journal of quantitative criminology
VO 15
IS 4
SP 451
OP 493
A1 Cohen, Jacqueline
A2 Tita, George E.
LA English
YR 1999
UL https://krimdok.uni-tuebingen.de/Record/1764275403
AB This article proposes a new method for examining dynamic changes in thespatial distribution of a phenomenon. Recently introduced exploratoryspatial data analysis (ESDA) techniques provide social scientists with anew set of tools for distinguishing between random and nonrandom spatialpatterns of events (Anselin, 1998). Existing ESDA measures, however, arestatic and do not permit comparisons of distributions of events in the samespace but across different time periods. One ESDA method—the Moranscatterplot—has special heuristic value because it visually displayslocal spatial relationships between each spatial unit and its neighbors. Weextend this static cross-sectional view of the spatial distribution ofevents to consider dynamic features of changes over time in spatialdependencies. The method distinguishes between contagious diffusion betweenadjoining units and hierarchical diffusion that spreads broadly throughcommonly shared influences. We apply the method to homicide data, lookingfor evidence of spatial diffusion of youth-gang homicides acrossneighborhoods in a city. Contagious diffusion between neighboring censustracts is evident only during the year of peak growth in total homicides,when high local rates of youth-gang homicides are followed by significantincreases in neighboring youth- nongang rates. This pattern is consistentwith a spread of homicides from gang youth to nongang youth. Otherwise, theincreases in both youth-gang and youth- nongang homicides generally occursimultaneously in nonneighboring tracts.
K1 hierarchical diffusion
K1 contagious diffusion
K1 spatial diffusion
K1 exploratory spatial data analysis
K1 Homicide
DO 10.1023/A:1007596225550