Nudging down burglary

To reduce the number of residential burglaries, particularly at repeat postcode locations.

To reduce the number of recorded residential burglaries in the six months post-delivery of nudge leaflets.

In the 12 months between January and December 2019, Durham Police recorded 2,829 crimes of residential burglary.

Analysis of these offences identified that 6.7% of all individual properties suffered from repeat victimisation, and 19.2% of all properties within the same postcodes suffered burglary offences.  

Analysis of the methods used by the offender identified that a third of offences occurred when properties were left insecure. This made the properties vulnerable to a motivated offender.  

A nudge leaflet was delivered into repeat residential burglary locations by local neighbourhood police team officers. Locations were randomly assigned to a treatment or controlled location.

Leaflet design

The nudge leaflet was designed specifically for this intervention and used the MINDSPACE / EAST mnemonic. 

MINDSPACE

• Messenger – we are heavily influenced by who is communicating information. 
• Incentives – our responses to incentives are shaped by predictable mental shortcuts. 
• Norms – we are heavily influenced by what others do. 
• Defaults – we ‘go with the flow’ of pre-set options. 
• Salience – our attention is drawn to novel things that seem relevant to us. 
• Priming – our actions are often influenced by subconscious cues. 
• Affect – our actions can be powerfully shaped by our emotional associations. 
• Commitments – we seek to be consistent with our public promises and to reciprocate actions. 
• Ego – we act in ways that make us feel better about ourselves. 

EAST

• Easy – simplify and breakdown the message and provide a clear next step. 
• Attractive – grab attention through surprise, novelty or anything to stand out. 
• Social – describe the behaviour as normal for that group. 
• Timely –  prompt people at the decision point or when they’re receptive. 

The leaflet was issued to each address in the postcode location within a short period of time shortly after a burglary. It contained: 

• an embedded Google image of the street
• specific information relating to the tactics used by the offender targeting that postcode
• information about what to do to reduce the chance of becoming a victim of such crime

The force conducted a randomised control trial (RCT). The Cambridge randomiser tool was used to allocate repeat burglary postcodes into either a treatment or control group.

The following properties were excluded from inclusion in the RCT.

1. The property was a commercial premises, multi-occupancy, flat or business property.
2. The offence involved violence, damage or was domestic abuse related.
3. The offence occurred in an unoccupied property.
4. The offence had occurred in a single pattern of crime/reporting.

Treatment group

The treatment group consisted of 157 postcodes and this group received the nudge leaflet. A certificate of service was completed to ensure compliance with delivering the leaflets. It also measured houses targeted, time delivering and rank delivering the leaflet. 

Control group

The control group consisted of 154 postcodes and this group did not receive the nudge leaflet.

Analysis

Durham police compared crime data for the treatment and control groups in the six months following the intervention. The analysis was done using a paired t-test on Statistical Package for Social Sciences (SPSS) to establish the difference in reported residential burglaries between the treatment and control group locations.

Using the paired samples t-test, burglary residential crimes recorded in postcodes in the control group decreased in the six-months post-randomisation. This difference was statistically significant.  

There was an even greater reduction post-randomisation in the treatment group when compared to the equivalent period pre-randomisation. This was also statistically significant.

The effects of the nudge leaflet demonstrated an 8.5% reduction in reported offences of residential burglary in the treatment group postcode location. 

The data was further examined to determine if there were any wider diffusion of benefits for other crime types. This identified that vehicle crime in the treatment and control groups had a similar trend to residential burglary – a 6 % reduction in reported offences of vehicle crime in the treatment group postcode location.

Cost

The cost of the nudge intervention was calculated based on the tracking undertaken within this experiment and totalled £3,125.94.

The cost of the leaflet delivery was absorbed into the normal duties of the respective teams. This was considered a cost-effective way to test the hypothesis that repeat locations can be targeted using nudge theory to reduce victimisation and provide some scalability to the wider use in policing.

The Office for National Statistics (ONS) Cost of Crime (ONS 2020) was used to calculate the police cost of crime on each postcode. The reduction in burglaries in the treatment group (-8.5%) was then removed from the cost per postcode. The cost difference per postcode was divided by the cost of the nudge per postcode. This method was applied over the three years prior to the trial, therefore finding an average for the treatment group.

It's acknowledged that crime has been dropping nationally, but data indicates that this was not the case in Durham during this period. The findings indicate that every £1 invested in a nudge leaflet brings an average recyclable saving of £2.70. 

The same methodology was applied to all vehicle crime, which shows average savings per postcode over a three-year period of £2.69. The benefits brought by using a nudge leaflet indicates that every £1 invested in the nudge leaflet brings total recyclable savings of £5.39.

Results indicate that repeat areas as defined by postcode in the treatment group experienced fewer burglaries than the control group in a six-month follow-up period.

Results also indicate that the nudge leaflet had a wider benefit in reducing vehicle crime in the treatment area.

The benefits brought by using a nudge leaflet indicates that every £1 invested in the nudge leaflet brings total recyclable savings of £5.39.

Over the past 12 months, several UK forces have provided an insight, overview and explanation of the process. This includes internationally with colleagues in Chile. 

Durham Police found that conducting an RCT with a tight control has several benefits for the force. These include: 

• improved integrity of the evaluation of nudge leaflets  
• improved credibility of the evaluation results  

The wider benefits of using nudge leaflets were: 

• ease of replication – nudge leaflets can be created for different forces and areas
• cost saving benefits – findings suggest every £1 invested in a nudge leaflet brings an average recyclable saving of £2.70
• resource efficiencies – the cost of the leaflet delivery can be absorbed into the normal duties of respective teams

Understanding the requirements from Google or other such companies around copyright legislation and the ability to use street maps was essential for implementation.