What is STAC?
STAC contains both a Time Analyzer and the STAC/Space module, which is a toolbox for analyzing the distribution of events on a map. STAC/Space includes automatic searches for two kinds of Hot Spot Areas (Hot Spot Ellipse and Isocrime), and also Nearest Neighbor Analysis (a test of significance for clustering), Mean Center, and radial searches for events occurring around an address or other location. (Detailed articles on each of these capabilities will appear in future issues of STAC News.) Training on STAC is available from the Justice Research & Statistics Association at their National Criminal Justice Computer Laboratory and Training Center in Washington, D. C. and at seminars throughout the country. Although some of the STAC/Space capabilities are available elsewhere, the Hot Spot Ellipse and Isocrime are unique to STAC. Other statistical methods for finding and defining the densest area on a map are based either on arbitrary boundaries (and thus subject to error) or on a high-crim
