This is the first of eight chapters on "Crime Travel Demand Modeling" from the user manual of CrimeStat IV, a spatial statistics package that can analyze crime incident location data.
This chapter, "Overview of Crime Travel Demand Modeling," defines "crime travel demand modeling" as an "application of travel demand forecasting." It is used by transportation planners to examine travel patterns over an entire metropolitan area and for forecasting future trends. Crime travel demand modeling is an application of travel demand theory targeted to crime analysis. Although crime has been decreasing in most U.S. metropolitan areas, the travel patterns of offenders has become increasingly complex. In order to illustrate this, the chapter contains a figure that shows a sample of 200 crime trips in Baltimore County that occurred between 1993 and 1997. Some of the trips are short; for some, the origin and destination are the same location; however, for other trips, the travel distances are substantial, indicating a complex pattern for crime trips that is not easily modeled by a simple distance decay-type function. Crime travel demand theory is a framework for understanding this complexity. There are two phases: an inventory (or data gathering) phase and a modeling phase. The chapter describes each of these phases. The CrimeStat crime travel demand module is distinguished from a journey-to-crime model, which is a single-stage model with the primary variable being distance. Crime travel demand modeling, on the other hand, is a predictive framework in which crime trips are a function of productions, attractions, and impedances. A discussion of the uses of a crime travel demand model addresses its research uses and its uses for policing. 1 table, 4 figures that include relevant computer screens, and 39 references