Are Studies Evaluating Cellphone Use & Car Crashes Overestimating Risk?

A new study evaluating earlier research of cellphone use and car crashes is saying that the risk claimed to be associated with driving and using a cellphone may be overestimated. News of this study was released just days after the National Transportation Safety Board recommended all states issue a ban on portable electronic device use while operating a motor vehicle.

Richard Young, Ph.D., a professor of research in Wayne State University’s Department of Psychiatry and Behavioral Neurosciences in the School of Medicine, looked at two studies -- one a 1997 Canadian study and the other a 2005 Australian study -- to identify possible bias. The news release reports that these studies used cellphone billing records of people who had been in a crash and compared their cellphone use just before the crash to the same time period the day (or week) before — the control window.

What Young thinks is that earlier investigators assumed that people were driving during the entire control period, while they may not have been, thus skewing the results.

“Earlier case-crossover studies likely overestimated the relative risk for cellphone conversations while driving by implicitly assuming that driving during a control window was full time when it may have been only part time,” said Young in the news release. “This false assumption makes it seem like cellphone conversation is a bigger crash risk than it really is.”

Young and his team conducted a new study using GPS to track the habits of 400 drivers for 100 days. The release states that Young then divided the days studied into pairs with the first day representing the "control" day and the second day representing the "crash" day from earlier studies. What the team found was that there was little consistency in the amount of time spent driving between the two days -- driving time on the control day was about a fourth of the driving time on the crash day.

“This underestimation of the amount of driving in the control windows by nearly four times could reduce cellphone conversation time in that control period,” Young said. “It makes it appear that there is less cellphone conversation in control periods than in the time just before a crash, making the relative risk estimate appear greater than it really is.”

Therefore, Young concluded that crash risk due to cellphone conversation is about one-fourth of what is estimated in previous studies -- close to normal baseline driving.

Young, considering NTSB's recent recommendation, has said he thinks the ban may go too far in not allowing cellphone conversations on the road.

“Recent real-world studies show that cellphone conversations do not increase crash risk beyond that of normal driving — it is the visual-manual tasks that take the eyes off the road and the hands off the wheel that are the real risk,” said Young in the release.

In this, Young agrees with many other that texting could be dangerous while operating a vehicle. It was texting that resulted in a deadly crash in Missouri that the NTSB was investigating when it made its recommendation to ban all mobile device use while driving.

So perhaps its use of hands-free devices that could remain on the road, which is something many states already require if one is going to use a cellphone while operating a car. But NTSB includes even hand-free sets in its recommended ban and recent research states that hands-free devices can be just as risky as regular handsets.

"There is a large body of evidence showing that talking on a phone, whether hand-held or hands-free, impairs driving and increases your risk of having a crash," Anne McCartt, senior vice president for research at the Insurance Institute for Highway Safety, said to the Associated Press.

Jim Hedlund, a safety consultant and former National Highway Traffic Safety Administration official, recently examined 300 cellphone studies for the Governors Highway Safety Association. He couldn't recall a single study that showed drivers talking on a headset or hands-free phone were at any less risk of an accident than drivers with one hand on the wheel and a phone in the other.

A similar analysis for the government of Sweden recently came to the same conclusion: "There is no evidence suggesting that hands-free mobile phone use is less risky than handheld use."

What's missing is hard evidence that accidents are increasing because of cellphone use. One reason is that U.S. privacy laws have made it difficult for researchers to study whether cell phones were in use in accidents in the U.S. The two large studies that have been done -- the Canadian and Australian studies evaluated by Young -- found drivers were four times more likely to have a crash if talking on a cellphone. It didn't matter whether the cellphone was hands-free or hand-held. It is this finding, that Young believes he has debunked with his research.

If a ban on hands-free devices were enacted, some of said that they would have to ignore it. The Associated Press reported Bruce McGovern as one of these people.

McGovern, who owns four Massage Envy and four European Wax Center franchises in the Dallas area, said he spends up to four days a week on the road, traveling between his businesses.

"My business would go down. We'd have problems we couldn't solve. My employees wouldn't be able to reach me and get timely answers," McGovern said to AP.

"Customer issues that only I can resolve would have to be delayed. And in this day and age, customers want instantaneous results for things. They're not willing to wait three or four hours," he said.

McGovern, who said he uses hands-free technology 90 percent of the time, said he's been conducting business from his car for more than 20 years, starting with an early "bag phone" that predated today's much smaller cellphones.

"It's a total overreach of the government. It'll be enforced erratically. They can't even enforce the speed limits," McGovern said.

Boston attorney Jeffrey Denner said he racks up at least 25 billable hours each week while driving.

"I probably spend three hours a day on the phone in the car - minimum. In an hour, I can talk to 10 people. On my way to court, I call people to make sure witnesses are lined up. It's become a part of my life."

The Associated Press contributed to this report. 

This story has been updated since its original posting to correct an error.