NCJ Number
190384
Date Published
August 2000
Length
17 pages
Annotation
This report outlines the five steps involved in the geocoding process which brings tabular and geographic law enforcement data together based on a common geographic unit of analysis and discusses common problems faced by law enforcement agencies when geocoding law enforcement data.
Abstract
Geocoding is the process of bringing tabular and geographic law enforcement data together due to a common geographic unit of analysis. The purpose of geocoding is to assign tabular data to a location on the earth’s surface to visualize the spatial characteristics of the data. It is similar to placing a pin on a map in the appropriate location. In law enforcement, address is primarily used as the geographic unit of analysis to which tabular data are geocoded. Other units used consist of parcels, zip codes, census tracts, census blocks, or beats. This report outlines the five steps involved in the general process of geocoding law enforcement data. The first step, preparing the geographic and tabular files for geocoding, is the most important and can be the most time consuming of the steps. Step two consists of specifying the parameters of both the geographic or reference data and the tabular data to determine how the geographic units from each source will be matched successfully. Once the parameters are set, geocoding is just a push of a button that starts the Geographic Information System (GIS) software application’s geocoding process. Step four, reviewing the results, is a matter of determining whether the geocoding process was successful and how successful it was. The fifth and final step is only necessary when there is not a 100 percent geocoding rate. Once the data have been geocoded and problems have been determined by the geocoding process, there may be a need to respecify parameters and geocode again. Since the GIS software varies from agency to agency, this report did not detail the specific methodology of geocoding in a particular GIS software program.