"Philadelphia’s foot-patrol strategy was developed after a study in 2009 by criminologists from Temple University, which is in the 22nd district. A randomised trial overturned the conventional view that foot patrols make locals like the police more and fear crime less, but do not actually reduce crime. In targeted areas, violent crime decreased by 23%," explains The Economist.
"Such patrols work best if officers return to the same street several times in each shift, says Jerry Ratcliffe, director of Temple’s Centre for Security and Crime Science. A good officer will soon know everybody on his beat. It is important to 'spend time just standing on a street corner, chatting to people, getting a feel for the tempo and rhythm of a place.' Foot patrols work best in dense neighbourhoods, says Mr. Ratcliffe, where many people cannot afford air conditioning and so socialise on the street. Drunken disagreements beget violence. 'Half the people shot in Philadelphia are shot within two blocks of their address,' he says."