Distance-Decay Function
Definition
The empirical pattern that offence frequency declines with distance from the offender's anchor point, after a small zone of avoidance close to home.
- Field
- Geographical profiling
- Pattern
- Offence frequency declines with distance from anchor point
- Exception near home
- Small zone of avoidance close to the anchor
- Used in
- Probability-surface profiling models
Common questions
Why would an offender avoid committing crimes right next to their own home?+
Proximity to home raises the risk of being recognised by neighbours or acquaintances, so many offenders show a buffer zone of reduced activity immediately around the anchor point even though risk otherwise falls with distance.
How is a distance-decay function actually used in a live investigation?+
Analysts fit the function to the spatial pattern of a linked offence series and combine it with other geographic data to generate a probability surface highlighting the areas most likely to contain the offender's anchor point.
Related terms
- Anchor Point
- The offender's spatial base of operations, most often the home, sometimes the workplace or a partner's address. The point geographical profiling is...
- Buffer Zone
- The area immediately around an offender's anchor point where offence probability is suppressed because the offender avoids committing crimes near recognisable locations...
- Hit-Rate
- Performance metric for a geoprofile: the percentage of the search area that has to be examined before the anchor is found, lower...
- Jeopardy Surface
- The probability map output of geographic profiling, rendered as a colour-coded topographic display where high-probability zones for the anchor point appear in...
- Routine Activity Theory
- A criminological framework developed by Cohen and Felson (1979) that explains property crime as the product of three converging elements: a motivated...