For 20 years, it has been a widely-held belief that talking on a cellphone while driving is dangerous, but a new investigation shows cellphone use appears to have no effect on the number of car crashes. The new research uses data from a major cellphone provider and accident reports to contradict the influential 1997 study that connected cellphone use to increased crash risk.
"Using a cellphone while driving may be distracting, but it does not lead to higher crash risk in the setting we examined," said researcher Saurabh Bhargava, from Carnegie Mellon University. "While our findings may strike many as counterintuitive, our results are precise enough to statistically call into question the effects typically found in the academic literature. Our study differs from most prior work in that it leverages a naturally occurring experiment in a real-world context."
For the study, Bhargava and co-researcher Vikram S. Pathania examined calling and crash data from 2002 to 2005, a period when most cellphone carriers offered pricing plans with free calls on weekdays after 9 p.m. Identifying drivers as those whose cellphone calls were routed through multiple cellular towers, they first showed that drivers increased call volume by more than 7 percent at 9 p.m.
They then compared the relative crash rate before and after 9 p.m. using data on approximately 8 million crashes across nine states and all fatal crashes across the nation. They found that the increased cellphone use by drivers at 9 p.m. had no corresponding effect on crash rates.
Additionally, the researchers analyzed the effects of legislation banning cellphone use, enacted in several states, and similarly found that the legislation had no effect on the crash rate.
"One thought is that drivers may compensate for the distraction of cellphone use by selectively deciding when to make a call or consciously driving more carefully during a call," Bhargava said. "In the least, this study and others like it, suggest we should revisit the presumption that talking on a cellphone while driving is as dangerous as widely perceived."
He added that the study focused solely on talking on cellphones, and did not analyze the effects of texting or Internet browsing. "It is certainly possible that these activities pose a real hazard," he said.
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Source: Carnegie Mellon University