predictive policing professor shane d johnson (kate bowers, toby davies, ken pease) ucl department...
TRANSCRIPT
Predictive Policing
Professor Shane D Johnson
(Kate Bowers, Toby Davies, Ken Pease)
UCL Department of Security and Crime Science
Overview
• Some basic findings
• Background theory – optimal foraging theory
• Prospective crime mapping
• Optimizing predictions
• Influence of the street network
• Resources
Crime Concentration - Burglary
Crime Concentration - Burglary
Johnson, S.D. (2010). A Brief History of the Analysis of Crime Concentration. European Journal of Applied Mathematics, 21, 349-370.
Concentration at places: Repeat Victimization
Is Victimization Risk Time-Stable?Timing of repeat victimization
Johnson, S.D., Bowers, K.J., and Hirschfield, A.F. (1997). New insights into the spatial and temporal distribution of repeat victimization. British Journal of Criminology, 37(2): 224-241.
Explaining Repeat Victimisation
Boost Account
• Repeat victimisation is the work of a returning offender
• Optimal foraging Theory (Johnson & Bowers, 2004) - maximising benefit, minimising risk and keeping search time to a minimum-– repeat victimisation as an example of this– burglaries on the same street in short spaces of time would also be an
example of this
• Consider what happens in the wake of a burglary– To what extent is risk to non-victimised homes shaped by an initial event?
Johnson, S.D., and Bowers, K.J. (2004).The Stability of Space-Time Clusters of Burglary. British Journal of Criminology, 44(1), 55-65.
• Communicability - inferred from closeness in space and time of manifestations of the disease in different people.
An analogy with disease Communicability
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area
burglaries
Neighbour effects at the street level
Bowers, K.J., and Johnson, S.D. (2005). Domestic burglary repeats and space-time clusters: the dimensions of risk. European Journal of Criminology, 2(1), 67-92.
Johnson, S.D. et al. (2007). Space-time patterns of risk: A cross national assessment of residential burglary victimization. Journal of Quantitative Criminology, 23: 201-219.
Patterns in detection data?
For pairs of crimes:
– Those that occur within 100m and 14 days of each other, 76% are cleared to the same offender
– Those that occur within 100m and 112 days or more of each other, only 2% are cleared to the same offender
Johnson, S.D., Summers, L., Pease, K. (2009). Offender as Forager? A Direct Test of the Boost Account of Victimization. Journal of Quantitative Criminology, 25,181-200.
“If this area I didn’t get caught in, I earned enough money to see me through the day then I’d go back the following day to the same place. If I was in, say, that place and it came on top, and by it came on top I mean I was seen, I was confronted, I didn’t feel right, I’d move areas straight away …” (P02)
Summers, Johnson, & Rengert (2010) The Use of Maps in Offender Interviewing. In W. Bernasco (Ed.) Offenders on Offending. Willan.
“The police certainly see a pattern, don’t they, so even a week’s a bit too long. Basically two or three days is ideal, you just smash it and then move on … find somewhere else and then just repeat it, and then the next area …” (RC02)
Summers, Johnson, & Rengert (2010) The Use of Maps in Offender Interviewing. In W. Bernasco (Ed.) Offenders on Offending. Willan.
High
Low
Risk
Forecasting - ProMap
Bowers, K.J., Johnson, S.D., and Pease, K. (2004). Prospective Hot-spotting: The Future of Crime Mapping? The British J. of Criminology, 44, 641-658.
Event driven and Time Stable factors
Event driven and Long-term factors(7- day forecast)
Johnson, S.D., Bowers, K.J., Birks, D. and Pease, K. (2009). Predictive Mapping of Crime by ProMap: Accuracy, Units of Analysis and the Environmental Backcloth, Weisburd, D. , W. Bernasco and G. Bruinsma (Eds) Putting Crime in its Place: Units of Analysis in Spatial Crime Research, New York: Springer.
Resources
• Fielding & Jones (2012) – Disrupting the optimal forager…. Journal of Police Science and Management– 38% reduction in residential burglary!– 29% reduction in TFMV!
• JDi Briefs (http://www.ucl.ac.uk/jdibrief/analysis)
• POP guide (http://www.popcenter.org/tools/repeat_victimization/)
• Vigilance Modeller (https://www.vigilancemodeller.net/)
• Risk Terrain Modelling (http://www.rutgerscps.org/rtm/)