The Michigan YVPC Crime Map Library contains links to individual maps depicting the relative rates of crime incidents in different regions of Flint, Michigan. Each map provides a visual summary of the incidence of a specific type of crime (arson, assault offenses, etc).
The City of Flint Police Department and the City of Flint’s Department of Information Services provided all the crime incident data.
What is a Crime Incident?
A crime incident is an event where a police officer suspects there have been one or more crimes. For each crime incident, a police officer records the date, time, and location (e.g., address). The officer also records the crime(s) that may have occurred and information about any crime victims such as the victim’s age, gender, and race.
How to Read the Maps
All of the maps show:
- The Flint City borders (a thick black line) and all streets and highways within the city and just beyond the city borders
- Lakes, reservoirs, and the Flint River (in blue) in and around Flint
- City parks – parcels outline with a light blue border
- Flint public schools – open schools indicated with a dot; closed schools indicated with an X
- Hurley Hospital – a small purple square just to the left of the city’s center
We represent the relative rate of crimes in the maps using different colors for specific areas of Flint. The areas with relatively low rates of crime are clear. The areas with slightly higher rates of crime start with a dark green overlay. As the crime rates rise, the areas are colored lighter green to yellow to orange to red. The bright red areas have the highest rates of crime. The areas with the highest rates of crime are often called “hot spots.”
Data Analysis
We used the crime incident data to count crimes and to count crime victimizations in specific locations throughout the City of Flint. Because we have information about the age of crime victims, we can also count violent crimes against youth (24 yrs or younger).
We used a Kernel Density Function in a geographic information systems software program called ArcGIS to compute the rate of crime incidents for specific areas. The Kernel Density Function calculates the geographic density of crime incidents for each point on the map and then “smooths” these density calculations to estimate the rate of crimes per square mile for wider areas.1
1 For a more complete and more technical explanation of using the Kernel Density Function to estimate crime rates, see:
http://en.wikipedia.org/wiki/Kernel_density_estimation
http://www.icpsr.umich.edu/CrimeStat/files/CrimeStatChapter.8.pdf
http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=How%20Kernel%20Density%20works