BOCSAR looked into the impact of additional police on rates of crime and arrests, by exploiting a large increase in the size of the NSW Police Force in the lead up to the 2003 NSW State Election.
Between 2002 and 2003 the size of the police force increased by 7.2%. This equates to an average increase of about 10 additional officers per Local Area Command.
This increase in police numbers is a gold-mine for crime researchers because there were few variables connected to this, apart from political point scoring. The study could then control for other relevant factors and crime and arrest rates in the periods before and after the recruitment campaign could be compared.
The analysis focused on offences known to be less susceptible to reporting and detection bias, namely murder, robbery, burglary, theft and car theft. Some other offences, such as sexual assault or domestic violence, were not included as they may increase in part because of changing community standards and higher reporting rates.
The study found that a 1% increase in the size of the police force generated:
- a 0.8% reduction in theft;
- a 1.1% reduction in car theft;
- a 0.63% reduction in aggregate property crime; and
- no convincing reductions in other crimes.
This roughly equates to one additional officer preventing 1.4 thefts, 0.36 motor vehicle thefts and 1.8 property crimes each month
The study found that there was no reduction in violent crime caused by the increase in police numbers.
Reason for decrease in property crime
For a given increase in police numbers, a change in arrest rate would either be a function of the deterrence rate or the incapacitation effect. The difference is that, where deterrence takes place, people are choosing to commit less crime because they are scared of being caught. The incapacitation effect sees that people who would otherwise commit crimes cannot do so because they are already in prison.
In sum, the report did not find evidence that an increase in police numbers generates a significant change to the arrest rate. This indicated that any change in crime that actually occurred, in regards to theft-related offences, were the result of slightly greater deterrence rather than incapacitation.
Cost versus benefit
The report also considered whether the wage cost of an additional officer is offset by the small benefit seen in property and theft offences. Ultimately, the report said that the costs of a slightly higher crime rate were more than the cost of an extra police salary, at least when using data from the early 2000s.
In this analysis, Mr Young used insurance claims data to find that the cost of a motor vehicle theft (in 2002) was about $6,000 per vehicle. Meanwhile, the cost of a NSW general duties constable (in 2005) was around $50,000 per year.
Using the findings above, this means that each additional police officer is able to offset almost half of their annual salary by deterring motor vehicle thefts alone. If other theft and property crime is added to this, it is likely that the savings in the cost of crime would offset the extra police salary.
This report does recognize that the findings for cost savings may not be generalizable to the present day. This is because there are modern innovations in security technology which mean that police play less of a role in preventing theft.
At the same time, these forms of theft and property crime would have fallen swiftly since the 2000s. Since this time, the rate of property crime has halved. Robbery without a weapon was down 64%. This means that the effect of police in deterring this would be weakened.
Bang for buck
It is also important to consider that this BOSCAR study did not consider whether the public funds of providing a police salary could better decrease crime through other means.
According to a 2012 BOCSAR report though, a more cost-effective strategy would be a committed investment towards alleviating, rather than just policing, underlying causes of criminal behaviour.
This report highlights the difference between reactive and proactive spending, stating “Measures that affect the economic well-being of the community provide more potential leverage over crime than measures that influence the risk of arrest.”
A 1% increase to income created a decrease in crime much greater than a 1% increase in arrest probability. Income effects were 14 times larger for property crime and about 5 times larger for violent crime. The study of justice reinvestment finds that similar benefits are offered by investment into education, social welfare and family programs.
This data suggests that the salary of a police officer could be better used to decrease crime through spending efforts that target the true causes of crime; such as poor education, employment, mental health or family dysfunction.