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1.
Over a period of 4 years (1997–2000), British Columbia (BC) experienced tremendous growth in the illicit production and distribution
of domestically grown marijuana. By the close of 2000, each policing jurisdiction in BC had adopted a particular policy in
response to grow operation proliferation. In summary, four policy responses were noted. First, some maintained the status
quo wherein enforcement of police initiated investigations and citizens’ tips continued, but with no additional resources
specifically dedicated to grow operations. Second, some jurisdictions suspended the majority of investigation and enforcement
of grow operations. Third, some agencies implemented or reinforced existing resource intensive drug squads, which focused
on trafficking, sales and production of all types of drugs. Finally, some of the jurisdictions formed specialized tactical
units known as “green teams” that focused solely on the enforcement of marijuana production. In this paper, we evaluate the
effectiveness of green teams using a Geographic Information System (GIS) and difference-in-difference estimates. The results
indicate that green teams decrease grow operations within their target area without significant displacement to surrounding
areas.
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George E. TitaEmail: |
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Jason Gravel Blake Allison Jenny West-Fagan Michael McBride George E. Tita 《Journal of Quantitative Criminology》2018,34(1):189-219
Objectives
This study proposes a theoretical framework for understanding two empirical findings from gang research: (1) gangs are generally racially homogenous, even in heterogeneous environments, and (2) gang violence tends to be intra-racial. We draw from the extensive literature on street gangs as well as from research on group formation and status-enhancing behavior to develop a theoretical model of gang formation.Methods
Using game theory, we model the simultaneous decisions of individuals to commit status-enhancing acts of violence and to seek protection by joining a gang. We then conduct computer simulations to examine the resulting patterns of violence and gang composition.Results
We demonstrate that as long as some social distance exists between racial groups in a community, gang violence will be intra-racial and gangs will be homogenous. We find that our results are robust to a number of simple variations of the model and allow us to generate several hypotheses about the nature of gang formation and patterns of violence.Conclusions
When violence is motivated by socially constructed rewards, socially closer targets are likely to yield greater rewards. In such a system, individuals must reduce their likelihood of victimization by entering a social contract of non-violence (i.e. gang membership) with individuals who might view them as status-enhancing targets (i.e. socially close individuals). The result is that gangs are made up of socially close individuals interested in attacking other socially close individuals. Therefore, gangs tend to be racially homogenous and violence is overwhelmingly intra-racial.3.
M. B. Short M. R. D’Orsogna P. J. Brantingham G. E. Tita 《Journal of Quantitative Criminology》2009,25(3):325-339
We develop a mathematical framework aimed at analyzing repeat and near-repeat effects in crime data. Parsing burglary data
from Long Beach, CA according to different counting methods, we determine the probability distribution functions for the time
interval τ between repeat offenses. We then compare these observed distributions to theoretically derived distributions in
which the repeat effects are due solely to persistent risk heterogeneity. We find that risk heterogeneity alone cannot explain
the observed distributions, while a form of event dependence (boosts) can. Using this information, we model repeat victimization
as a series of random events, the likelihood of which changes each time an offense occurs. We are able to estimate typical
time scales for repeat burglary events in Long Beach by fitting our data to this model. Computer simulations of this model
using these observed parameters agree with the empirical data.
相似文献
M. B. ShortEmail: |
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John R. Hipp George E. Tita Lyndsay N. Boggess 《Journal of Quantitative Criminology》2011,27(1):27-51
There are numerous instances in which researchers wish to measure the rate of intra- or inter-group interactions (whether
positive or negative). When computing such measures as rates there is great uncertainty regarding the appropriate denominator:
we analytically illustrate how the choice of the denominator when calculating such rates is not trivial and that some existing
strategies create a built-in relationship between the computed rate and the group composition within the entity. Another strand
of prior work only focused on the relative occurrence of intra- versus inter-group events, which does not account for the
important theoretical possibility that both types of events might increase in certain social contexts. Our approach provides
an advance over these earlier strategies as it allows one to take into account the relative frequency of interaction between
members of different groups, but then translates this into per capita rates. We also provide an empirical example using data
on inter- and intra-group robbery and aggravated assault events for block groups in a section of the city of Los Angeles to
illustrate how our procedure works and to illustrate how other approaches can lead to dramatically different conclusions. 相似文献
6.
The majority of spatial studies of crime employ an inductive approach in both the modeling and interpretation of the mechanisms
of influence thought to be responsible for the patterning of crime in space and time. In such studies, the spatial weights
matrix is specified without regard to the theorized mechanisms of influence between the units of analysis. Recently, a more
deductive approach has begun to gain traction in which the theory of influence is used to model influence in geographic space.
Using data from Los Angeles, we model the spatial distribution of gang violence by considering both the relative location
of the gangs in space while simultaneously capturing their position within an enmity network of gang rivalries. We find that
the spatial distribution of gang violence is more strongly associated with the socio-spatial dimensions of gang rivalries
than it is with adjacency-based measures of spatial autocorrelation. 相似文献
7.
Khorshidi Samira Carter Jeremy Mohler George Tita George 《Journal of Quantitative Criminology》2021,37(2):361-391
Journal of Quantitative Criminology - Crime diversity is a measure of the variety of criminal offenses in a local environment, similar to ecological diversity. While crime diversity distributions... 相似文献
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Diffusion in Homicide: Exploring a General Method for Detecting Spatial Diffusion Processes 总被引:2,自引:0,他引:2
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. 相似文献
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