Police numbers add up to less crime

Patrolling policeThe police force and policing policy have been the a hot topic this summer, starting with concerns of police cuts, the phone hacking scandal leading to the Met looking for a new Chief, and in recent weeks the riots, with questions being asked about the value of police on the ground. A new study suggests that police patrols are a highly effective tool for cutting crime.

A study from the Centre for Economic Performance published in the American Economic Review studied the impact of the increased use of police patrols for a period after the 7/7 London terrorist attacks in 2005.

"In the wake of the 7/7 attacks, crime fell by around 12 per cent in areas where police patrols were most concentrated," says Professor Stephen Machin, an author of the study. "By our estimates, a 10 per cent increase in resources for police patrols led to a three per cent drop in crime."

"Typically, research of this type can’t pick out the real effect of police on crime," says co-author Mirko Draca. "In fact, if you look at the data there are more police in areas where crime is already high. This is because the police have to locate their resources in places where they’re most needed."

"However, the period after the 7/7 attacks provided a 'natural experiment' where we were able to precisely pick out the true causal effect of police on crime.

While earlier research had suggested that the effect of police patrols might be close to zero, the new findings uncovered a "decisive effect", according to the researchers.

The study is directly relevant to current conditions in the aftermath of the recent riots across England.

"The current large deployment of police across the country has similarities with the post-7/7 period. Once they were significantly increased, the patrols appear to have acted as a strong deterrent to further riots," says Mr Draca.

"In the case of 7/7, crime rebounded again immediately after patrols were withdrawn. However, in the current operation many potential criminals may be caught up in the court system, leading to a small medium-term reduction of crime.

The research concludes that sizable police patrols is a reliable tool.

"We don’t argue that increased police numbers should be the sole focus on anti-crime policy but our research suggests that if the police are resourced properly, the effects can be powerful," adds Mirko Draca.

"The planned 20 per cent cuts in police resources will inevitably put upward pressure on crime rates. Our estimates indicate that crime could rise by around six per cent as a result of the planned cuts."