Mobility polygons and the geometry of co-offending
Marcus Felson, Martin A. Andresen, Richard W Frank · 2012
Introduction Scientists often learn to summarize a lot of information with a single scale. The Kelvin temperature scale, the Gini ratio of inequality, life expectancy at birth, the Richter seismic intensity scale, and the Fujita scale of tornado intensity – all of these serve a summary purpose for their respective disciplines. None of these indicators crowd out other research or measures, but each one helps synthesize and focus a good deal of information.1 Our concern in this chapter is to find a general indicator for the spatial analysis of crime events, drawing upon what is already in the crime analytical literature. We do not declare that we have found a single indicator that does the job – time will tell whether that is true. Nor do we claim first credit – that belongs to Burgess (1925) and more recently to Groff and McEwen (2007). But in this chapter we broaden their work and propose a more general scale to summarize a good deal of information about the spatial span for a single crime event. We hope this scale helps compare crime events in their spatial reaches. We demonstrate this comparison using real data on over 4,000 crime events within a single city.