The Kansas City preventive patrol experiment was a landmark experiment carried out between 1972 and 1973 by the Kansas City Police Department of Kansas City, Missouri. It was evaluated by the Police Foundation. It was designed to test the assumption that the presence (or potential presence) of police officers in marked cars reduced the likelihood of a crime being committed. It was the first study to demonstrate that research into the effectiveness of different policing styles could be carried out responsibly and safely. The Kansas City preventive patrol experiment was a landmark experiment carried out between 1972 and 1973 by the Kansas City Police Department of Kansas City, Missouri. It was evaluated by the Police Foundation. It was designed to test the assumption that the presence (or potential presence) of police officers in marked cars reduced the likelihood of a crime being committed. It was the first study to demonstrate that research into the effectiveness of different policing styles could be carried out responsibly and safely.