Drivers on Cell Phones Kill Thousands, Snarl Traffic (LiveScience)

Finally, empirical proof you can blame chatty 20-somethings for stop-and-go traffic on the way to work. A new study confirms that the reaction time of cell phone users slows dramatically, increasing the risk of accidents and tying up traffic in general, and when young adults use cell phones while driving, they’re as bad as sleepy septuagenarians. “If you put a 20-year-old driver behind the wheel with a cell phone, their reaction times are the same as a 70-year-old driver who is not using a cell phone,” said University of Utah psychology professor David Strayer. “It’s like instantly aging a large number of drivers.” The study was announced today and is detailed in winter issue of the quarterly journal Human Factors.

Cell phone distraction causes 2,600 deaths and 330,000 injuries in the United States every year, according to the journal’s publisher, the Human Factors and Ergonomics Society. The reason is now obvious: Drivers talking on cell phones were 18 percent slower to react to brake lights, the new study found. In a minor bright note, they also kept a 12 percent greater following distance. But they also took 17 percent longer to regain the speed they lost when they braked. That frustrates everyone. “Once drivers on cell phones hit the brakes, it takes them longer to get back into the normal flow of traffic,” Strayer said. “The net result is they are impeding the overall flow of traffic.”

Strayer and his colleagues have been down this road before. In 2001, they found that even hands-free cell phone use distracted drivers. In 2003 they revealed a reason: Drivers look but don’t see, because they’re distracted by the conversation. The scientists also found previously that chatty motorists are less adept than drunken drivers with blood alcohol levels exceeding 0.08.

While it’s intuitively obvious that people chatting on the phone are less attentive, all things being equal, than they’d be if they were paying attention, the magnitude of the difference is surprising. One wonders if the scientists are properly controlling for other variables. Indeed, a look inside their stats makes the results rather dubious:

The estimates of annual deaths reported in this week’s article (2,600) may well be low. The number, for U.S. deaths related to drivers using cell phones, comes from a 2002 study by the Harvard Center for Risk Analysis (HCRA). Researchers then estimated that the use of cell phones by drivers caused approximately 2,600 deaths. Because data on cell phone use by motorists are limited, the range of uncertainty is wide, those researchers said. The estimate of fatalities in that HCRA report ranged between 800 and 8,000.

Any methodology with a range that wide–a factor of ten more or less?!– is worse than worthless. The statistics are spouted and attributed to “scientists” and “experts” when, in fact, the proper answer is “we have no clue whatsoever.”

The estimates are based largely on mathematical models, but they are not without basis. In 2001 in California, for example, “at least 4,699 reported accidents were blamed on drivers using cell phones, and those crashes killed 31 people and injured 2,786,” according to an analysis by The Los Angeles Times. That number can expected to be low, because of the lack of formal procedures for noting cell phone use as a cause of a traffic accident.

Well, no. So, we have 4,699 accidents. Out of how many total? Blamed? By whom? On what basis?

And, finally, we get to the Utah study itself:

Participants in the simulator used dashboard instruments, steering wheel and brake and gas pedals from a Ford Crown Victoria sedan, surrounded by three screens showing freeway scenes and traffic, including a “pace car” that intermittently hit its brakes 32 times as it appeared to drive in front of study participants. If a participant failed to hit their own brakes, they eventually would rear-end the pace car. Each participant drove four simulated 10-mile freeway trips lasting about 10 minutes each, talking on a cell phone with a research assistant during half the trips and driving without talking the other half. Only hands-free phones were used to eliminate any possible distraction from manipulating a hand-held cell phone.

So, they played arcade games? For 10 minutes at a time? And from this they extrapolated to real life driving conditions?