330 vehicles stopped only 4 arrested for DUI are police checkpoints effective?

Belmont, New Hampshire - This checkpoint, about a mile west of the Laconia line, was set to run from 9 p.m. Friday to 3 a.m. Saturday on one of the busiest roads in the Lakes Region, with 20,000 cars passing each day. It was placed within a quarter-mile of seven restaurants with bars, a state liquor store and several convenience stores, police Sgt. Richard Mann said.

By the time the checkpoint was dismantled at 3 a.m., police had stopped 330 vehicles and had made four arrests for drunken driving, four arrests for drugged driving and one arrest of a person on a U.S. immigration charge. In addition, 28 drivers had been cautioned about vehicle safety issues.

“Actually, that's about what we had last year,” said Mann, sounding disappointed.

But he remained optimistic about the checkpoint's mission.

“If we stop a drunk or drugged driver, we've done a good thing. But with the publicity and the awareness that comes with these checkpoints, there's a deterrent effect. We stopped some people, but who knows how many people didn't drink and drive this week because they heard about the checkpoint? That's what we hope for.”

http://www.unionleader.com/article/20120624/NEWS07/706249939