Sunday, August 11, 2013

Statistics In The Real World

This sounds interesting:
"Using a cellphone while driving may be distracting, but it does not lead to higher crash risk in the setting we examined," said Saurabh Bhargava, assistant professor of social and decision sciences in CMU's Dietrich College of Humanities and Social Sciences. "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 the London School of Economics and Political Science's 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.


Steve USMA '85 said...

Two things, first; traffic is usually lighter after 9 PM and thus it may be that cell phone use doesn't increase the number of accidents since after 9, there are fewer opportunities to hit something. Second; legislation banning the use of cell phones while driving doesn't have a measurable affect on accidents because it doesn't have a measurable affect on cell phone usage. People just put the phone down if & only when they see a cop.

Darren said...

Seeing a cop and putting the phone down shouldn't have an effect on *accidents* unless most accidents happen right in front of cops.

Yes, traffic is lighter after 9pm, that's why they looked at the *rate* of accidents and not the number. If your point, though, is that there's less traffic for the "phone talker" to strike or swerve, then I understand your point completely. Less traffic shouldn't change the rate of single car accidents, though.

Anonymous said...

All I have is anecdotal evidence. Whenever I see a driver doing something incredibly stupid, almost always they are yakking on the phone.

Hang up and DRIVE!

Darren said...

I'm with you on the anecdotal but the numbers don't bear out what we think--unless those who *aren't* talking on the phone are capable of avoiding the accidents that the talkers might cause!