Digital maps are often used to identify crime problems by displaying the spatial distribution of crime and looking for "hot spots" or concentrations of crimes in specific geographic areas. Because of the power of GIS, the analyst can analyze crimes by specific type and time of day. Further, mapping provides a means of examining potential conditions that support or facilitate the existence of a crime problem. This is done by drawing on a vast array of geographically referenced data, from street networks and lighting to information about demographics and city services. Although mapping does not directly assist in determining an appropriate intervention for a crime problem, it supports that effort through the researcher's ability to analyze accurately the underlying causes of a crime problem. Because GIS provides the user with the ability to analyze several layers of information and easily alter the data that appear on the map, it is a useful tool for experimenting with the likely impact of various kinds of interventions. Further, GIS can be used to analyze the distribution of a crime or disorder problem in a specific study area before and after the implementation of an intervention. In addition, GIS can be used to analyze the possibility of crime displacement or the diffusion of benefits. 11 references