The evidence base for routine interventions: Findings from the UK, Western Australia & New Zealand

Mr Simon Williams M.St (Cantab)1

1Manager, New Zealand Police Service 

Hot spots policing strategies have been tested the world over, resulting in a strong body of evidence to support the adoption of police targeting places which suffer from concentrated levels of crime. An ongoing systematic review and meta-analysis (Braga, et al. 2019) reveals that since 2014 there has been a 242% (46 studies) increase in the number of experimental or quasi-experimental studies of hot spots interventions by police. However, none of these studies has been able to measure how police can maximise deterrence of crime with minimal increases in police patrol, at minimal cost to both resource and intrusion on communities within hot spots – evidence from Western Australia now provides us with some answers to this question.

This paper takes a walk through the early days of hot spots policing, going on to examine evidence from studies in the UK, where the ‘Koper Curve’ was tested for the first time in an experiment which saw frequency and length of patrol randomly assigned across 7 hot spots. It then moves to Western Australia which saw 15 hot spots randomly assigned periods of up to 20 consecutive days in which individual hot spots remained in the control condition. Findings from this study tell us not only what impact police presence has on initial deterrence, but how long residual deterrence lasts before both frequency and severity of offending significantly spike – can we deploy less patrol to hot spots and still cool down crime? Finally, we move to New Zealand where work is underway to replicate the West Australian approach. This asks, for the first time in an NZ context, how street level crime, crime harm and demand concentrates over time in this unique geography and will also investigate officer perceptions of crime concentration.


Simon began his police career with the West Midlands Police in 2002, working across frontline operational roles including Neighbourhood Policing, Roads Policing and Offender Management. During his time leading offender management Simon took the opportunity to complete a Master’s Degree in Applied Criminology and Police Management at the University of Cambridge. In 2016 Simon transferred to the Western Australian Police Service as a Senior Sergeant, leading a team under The Police Innovation and Improvement Command to operationalise Evidence Based Policing. During his 18 year career as a sworn officer, Simon has led and operationalised numerous field experiments testing hot spots policing, procedural justice, deferred prosecutions and crime prevention through environmental design. In May 2019 Simon transferred to New Zealand Police Service as a Manager within the newly established Evidence Based Policing Centre. Simon leads a multi-disciplinary team of researchers, knowledge experts, service designers and experienced police officers to test police practice in an applied context, promote evidence based policing and build the capability of officers and staff to make decisions based on the best available evidence of what works, what doesn’t and what looks promising in policing.

Simon supports the Australia and New Zealand Society of Evidence Based Policing in the role of Secretariat and is currently the Managing Editor of the society’s journal, Police Science.

In 2019 Simon was nominated as a Fellow of the American Society of Criminology, Division of Experimental Criminology.