In the debate over the police tactic known as stop-and-frisk, some believe a good benchmark of its success is how often the stops result in arrest or the discovery of a weapon or other contraband. Jerry Ratcliffe, professor of criminal justice at Temple and an advisor to the Philadelphia Police Department, said arrest data are not the best way to measure stop-and-frisk. Officers want to "increase the sense of certainty of police intervention if you carry a gun," Ratcliffe said. Fewer arrests and seizures of weapons could indicate the tactic is working, he said.