Wednesday, December 14, 2011

Cell Phones, Driving, and Decision Errors

I suspect that the NTSB is right that, on net, the costs from distracted driving while talking on a mobile phone outweigh the benefits. But this is a classic example of how decision errors can creep into decision making. Consider the hypothesis that banning mobile phone use while driving will save lives.


Ban mobile phone use while driving Don't ban mobile phone use while driving
Mobile phone use while driving causes more deaths than it saves

0 Type I Error
(false negative)
Mobile phone use while driving saves more deaths than it causes Type II Error
(false positive)
0

Type I Error Costs If distracted drivers only killed themselves, why stop them? The hidden cost is that they typically run into someone else or they take their passengers with them. Drivers may be less careful with other peoples' lives. So, the Type I error costs are all the innocents killed by distracted drivers. This has been the focus of most of the studies and the policy.

Type II Error Costs Drivers with mobile phones have related information during Amber alerts. They have notified media outlets when traffic was bad due to wrecks and thus saved thousands of hours in commute time - during which some wreck could have occurred. They have been able to coordinate with their called parties, getting directions, etc., which saves time which has some value. And of course, they derive utility from the call. But if your job is highway safety, as board member of NTSB, how much do you value these? Since no one writes news stories about the wreck that did not occur from accurate traffic updates, they are largely hidden. Also, if your job is highway safety, you may not value lost time and utility as much as those who must give it up.

Let me repeat that I suspect that banning mobile phone use while driving is likely appropriate. I am just not certain that all the costs went into the decision.

5 comments:

  1. It is a fact that it is unsafe to text and drive. However, I would argue that a ban only motivates the driver to hide his actions, which is likely much more hazardous (unintended consequence).

    My fundamental issue with this suggested ban is the singling out of cell phones. There are multiple ways a driver can be distracted and it is seen every day on the roads; women applying makeup, people eating sandwhiches, parents screaming at their unruly children, etc. Are these actions any less unsafe? They also want to ban handsfree devices. Again, is this more hazardous than listening to and singing along with the radio or changing songs on your iPod?

    Instead punish distracted driving in general and make the consequences equal across the board. A life lost from driving while texting costs the same as one from a drunk driver as one from someone who loses control after droping a cigarette.

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  2. About Type II error costs; a driver can easily pull over to the side of the road safely while calling in a wreck or car accident. With bluetooth technology these issues should be obsolete anyways since drivers can keep their hands on the wheel. As for directions, if you use it as a GPS you shouldn't need to shuffle with it; just mount your cell and it will tell you where to go. No one should be actively surfing the net while driving.

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  4. One alternative to banning cell phones would be to try and make their usage safer (ex: no hands - headsets/bluetooth devices). Many states and cities have taken this route, but its likely result is drivers taking less care when talking on the phone than when they were holding the phone to their ears - resulting in more reckless driving overall.

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    Replies
    1. Studies have found that distraction levels are actually higher using hands free devices. People concentrate on using the right phrases and code words to talk to their cars/phones and end up not driving as well.

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