COMPSTAT Weekly Crime Mapping


Preventing crime and working to ensure a higher quality of life for
the general public is a primary goal of any police agency, particularly
at the local government level. For the City of Des Plaines, IL, these
efforts led the city’s Police Department to start using a crime
prevention technique, referred to as Comparative Statistics (COMPSTAT),
that use crime statistics gathered over time to highlight incident
patterns and high crime areas. By analyzing these patterns, the
department can better focus their mitigation efforts in areas that are
experiencing a higher number of crime incidents. To help show these
patterns in a way that could be easily understood and disseminated by
all department staff, the department asked the city’s Geographic
Information System (GIS) personnel to generate both a weekly and monthly
map product that plotted each crime location.

Every week, the Police Records Division, which tracks all crime data
for the department, provides the GIS staff with a summary of the crime
incidents from the previous week. Included in each summary report is
the location of each incident, the date and time the incident occurred,
and the crime code (i.e. theft) associated with each location. Using
this information, the GIS staff is able to map out each crime location
and, since the data is provided every week, provide a map product to the
department showing the cumulative crime totals from the beginning of
each month to the end of the current week being reported. Over time,
various patterns in the data begin to emerge and higher crime areas
become visually apparent on each resulting map product.

Without GIS, these efforts would prove to be more difficult as it
would be challenging to understand where problems were emerging without
having a tool to visualize where they are located within the city. By
tracking crime locations using a spatial platform over the course of a
few weeks, or even a few months, the department can visualize where high
crime areas are and begin to implement practices that can help to
reduce the number of incidents that are occurring.