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Police patrols highly effective for cutting crime

PolicemanA new study from LSE’s Centre for Economic Performance shows that police patrols are a highly effective tool for cutting crime.

The study, published in the new issue of 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 3 per cent drop in crime’.

‘Typically, research of this type can’t pick out the real effect of police on crime’ said 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’.

‘Indeed, earlier research had suggested that the effect of police patrols might be close to zero but our research uncovers a decisive effect’.

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. So far, once they were significantly increased, the patrols appear to have acted as a strong deterrent to further riots’.

‘In the case of 7/7 crime rebounded again immediately after patrols were withdrawn.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 central message of the research is that sizable police patrols are one tool that policy-makers can count on. 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’.

‘Another message is that 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 6 per cent as a result of the planned cuts’.


Notes for editors: Panic on the Streets of London: Police, Crime and the July 2005 Terror Attacks by Mirko Draca, Stephen Machin and Robert Witt, American Economic Review, 101, August 2011, pp.2157-2181

For further information: contact Mirko Draca on +44 (0)20 7806 (m.draca@lse.ac.uk) ; or Helen Durrant at CEP on +44 (0)20 7955 7395 (h.durrant@lse.ac.uk).