Writing in the New York Times yesterday, Kent A. Sepkowitz called for all new vehicles sold in the US to be limited to 75 MPH, saying, “Speeding is the cause of 30 percent of all traffic deaths in the United States — about 13,000 people a year.” He goes on to compare speeding to alcohol, which he says is responsible for 39 percent of all traffic deaths, “But unlike drinking, which requires the police, breathalyzers and coercion to improve drivers’ behavior, there’s a simple way to prevent speeding: quit building cars that can exceed the speed limit.” The thing is, Mr. Sepkowitz has his number wrong. The National Highway Traffic Safety Administration, which Mr. Sepkowitz cites as his source, says 31% of people involved in fatal crashes in 2007 were speeding at the time. From this, we can draw several conclusions. The first is that while speed was a factor in these crashes, it is not given as the cause. The other obvious conclusion is that two thirds of people involved in fatal crashes were not speeding at the time. So, by Mr. Sepkowitz’s logic, isn't it actually safer to speed than it is to drive at or below the speed limit? Maybe we should call for a ban on not speeding. There’s a huge gap in the NHTSA’s numbers, meaning we don’t know what percentage of overall speeding traffic, nor what percentage of overall law-abiding traffic, was killed in road accidents. Therefore it’s impossible to determine the true statistical danger of speeding. Nor does the study state what the actual cause of all the accidents was. If, for instance, a person was killed by a truck running a red light, while that person was speeding, would speed or the running of the red light be considered the cause? The NHTSA doesn’t know, but would in that case list speed as a factor. We'd list "running of the red light." Mr. Sepkowitz goes on to contradict his own argument by stating that in 2006, “76 percent of speeding drivers killed in motor vehicle accidents had been drinking.” Wouldn't that suggest drinking, not speed, was the contributing factor to their deaths? But how should we limit the performance potential of vehicles to a speed which Mr. Sepkowitz feels is safe? “It’s called cruise control. In its common application, cruise control maintains a steady speed, but a minor adjustment would assure that vehicles, no matter the horsepower, never go past 75 miles per hour.” Hmm, perhaps Mr. Sepkowitz should stick to his important day job — you know, being vice-chairman of medicine at the Sloan-Kettering cancer center — rather than playing amateur car mechanic. [via NYTimes.com]