The journey-to-crime buffer zone: Measurement issues and methodological challenges

Purpose

The journey to crime is well-researched in criminology. Fundamental to many of these studies is the offending probability by distance function, a distribution comprised of two key components – distance decay and the buffer zone. However, it is difficult to measure this relationship accurately because of intensive data requirements. Here, we explore this challenge in detail and quantify data requirements.

Methods

We define and describe the buffer zone and outline two proposed explanations. Using this framework, four critical research considerations that avoid the ecological fallacy are identified, and a testing procedure proposed. Finally, we conduct simulation analyses to establish minimum data requirements.

Results

We conclude 50 or more observations are needed to reliably determine the shape of an offender's travel distribution, a number much higher than used in previous studies. Two empirical case studies of prolific predatory offenders support these findings.

Conclusion

Understanding crime journeys is relevant for both theory and practice. Crime travel is central to routine activity and crime pattern theories, and a critical factor in offender decision-making, target choice, spatial displacement, crime scripts, geographic profiling, crime prevention, and risk assessments. The relationship between distance and offending probability must be accurately measured to be properly understood.