Framework for Validating Geographic Profiling Using Samples of Solved Serial Crimes

This short paper was prepared for the NIJ Roundtable for Developing an Evaluation Methodology for Geographic Profiling Software (August 10 and 11, 2004) on approaches for validating geographic profiling (GP) methods. The paper presents a framework for validating any GP method or software package using solved serial crimes including data on crime locations and criminal residences or other anchor points (e.g., work location, girl friend’s residence, etc.). Findings from the literature and through analysis include: 1) the appropriate performance measure for GP (that matches policing needs and as extended in this paper) concerns prioritizing relevant areas for investigation; 2) future work should correct the performance measure of GP by excluding irrelevant areas from consideration such as rivers, lakes, cemeteries, etc. (past studies apparently did not do this); 3) additional model parameters may be able to be estimated in empirical studies such as the amount to expand the search area for a serial criminal beyond the minimum rectangle or other boundary enclosing crime sites; and 4) future validation studies for GP should compare alternative models, including simple models for benchmarking, and use holdout samples in a resampling scheme for validating performance. Acknowledgements The revision of this short paper incorporates knowledge gained from discussions with participants and organizers of the NIJ Roundtable for Developing an Evaluation Methodology for Geographic Profiling Software: Sean Bair, Patricia Brantingham, Keith Harries, Jay Lee, Derek Paulsen, Shari Pfleeger, Thomas Rich, Michael Shively, Debra Stoe, Ronald Wilson, and Robin Wilfong.