by Elizabeth L. Davison
Appalachian State University
William R. Smith
North Carolina State University
GIS represents a powerful research technology that can be used for mapping and studying the spatial distributions of various social phenomena, including events (crimes, illnesses, accidents), placements (social service, prison releases), and organizational services (police beats, school districts). One of the marvels of GIS is that it enables researchers to link seemingly unrelated data sets through a process called geocoding (matching addresses to geographical coordinates) which creates many types of relevant information for each spatial point. Five years ago we used GIS software to construct a data base containing tax assessor information, census data, official police records and 911 calls for service for the city of Raleigh.
Another powerful asset of GIS software is that it enables the researcher to aggregate data to different levels. For example, we aggregated the Raleigh data at the address level to face blocks (both sides of the street between two city blocks), city blocks, as well as larger geographic areas (census tracts). In general we find that traditional ecological constructs are best in explaining smaller units of analysis such as the face block (both sides of a street between two intersections) rather than the more commonly used census tracts and block groups that are assailable because of spatial heterogeneity concerns (e.g., a large areas such as a census tract can be half African American and half white and still be racially segregated within the area). Additionally, results from smaller units of analysis yield more specific policy recommendations.
In addition to the statistical analysis, GIS can create powerful
visuals to demonstrate findings. To illustrate, the Map of
1993
Robberies shows a cross-sectional view of the south western part of
Raleigh. The map is not layered except for streets (black lines) and
robbery incidents (a triangle represents one or more robbery
incidents). The plotting of robberies among the streets allows for a
better image of some of the city details since incidents of robberies
are infrequent compared to burglaries or larcenies. Also, robbery is
considered a more serious crime that is subsequently more likely to be
reported and less likely to be influenced by policing bias. A striking
observation of this map supports the assumption of the routine activity
approach that crime is not a spatially random event. Emerging from the
map are notable patterns in the distribution of robberies among face
blocks. These trends can be explained by both social disorganization
and routine activities factors (some of which we have not tested).
True to the concentric zone models of the Chicago School, robberies are
clustered around the center of the city (area 1) where businesses,
government offices and motivated offenders are in close proximity of
each other. In general, robbery incidents become less frequent away
from the center of the city. Surrounding the central business district
is the "transitional zone" (area 2) which consists of neighborhoods that
are typical of social disorganization neighborhoods. These
neighborhoods contain mixed parcels of residential and businesses,
concentrations of public housing surrounded by substandard rental
property, dense population, high unemployment, and many social ills that
contribute to the motivation of offenders. A notable exception to the
concentration of robberies in the downtown
area, is the clustering of robberies on the "campus main drag" (area 3)
which is located west of the capital and consists primarily of
businesses that cater to the university community. The high rate of
victimization in this area can be attributed to the routine activity
concepts of "opportunity" and "awareness space." Heavy vehicular and
pedestrian traffic brings a concentration of cars, people, products and
money into the area creating more opportunities for robbery and
"awareness space" for motivated offenders. Another surprising
clustering of robberies that are away from the business and transitional
zones is found in the lower left hand corner (area 4). This area
consists primarily of student apartments that are characterized by a lot
of transition and many anonymous interactions with neighbors. Both of
these factors create opportunities for crime victimization. Other
routine activities factors include that fact that no cul-de-sac street
have a robbery event since these areas are not in the "awareness space"
of most offenders. Conversely, the main thoroughfare has more crime due
to increase in awareness space and opportunities. Area 5 (towards the
upper left hand corner of the map) is virtually untouched by robbery
incidents. This area consists of predominantly single family dwellings
which caters to faculty and other professionals. A high concentration
of home ownership acts as guardianship over properties in this area.
In conclusion, GIS software has aided us in compiling a database that has
furthered the understanding of crime distributions for various geographical
boundaries. Since individuals do not often experience the "real world"
through administrative geographical boundaries such
as school districts,
census tracts and voting precincts, researchers need to have the flexibility
to study units of analysis that are determined by theoretical undergirding
rather than available resources.
Note: findings include research
by Elizabeth L. Davison, Sharon Glave Frazee, Kennon J. Rice, William R.
Smith, and Claudia Squire.
For further information see Smith, William R., Sharon
Frazee and Elizabeth Davison. "Towards and Integration of Routine
Activity and Social Disorganization Theories: A Socio-ecological Analysis
of Robbery." Criminology (forthcoming)
Source: This is a longer version of an article from April/May 2000 Sociation.
Want to see how urban design can influence crime rates? Oscar Newman's book Creating Defensible Space is now available online in *.pdf format.