Dangerous phones or safe drunks?

Alex Tabarrok at Marginal Revolution writes of a new study which compares Cell Phone Drivers and Drunk Drivers. It finds:

When drivers were conversing on a cell-phone, they were involved in more rear-end collisions, their initial reaction to vehicles braking in front of them was slowed by 8.8%, and the variability in following distance increased by 24.5%, relative to baseline. In addition, compared to baseline it took participants who were talking on the cell phone 14.8% longer to recover the speed that was lost during braking.

By contrast, when participants were legally intoxicated, neither accident rates, nor reaction time to vehicles braking in front of the particpant, nor recovery of lost speed following braking differed significantly from baseline.

One way to look at this, of course, is that its dangerous to talk while you drive. But another way is to notice that legally drunk drivers don't seem to be dangerous. This supports the claims of groups like DAMM and getMADD who say that current BAC standards for "drunk driving" (0.08) are unreasonably low. The "drunk" study participants had BAC's right around 0.08. It could be that the standards are "just right" in that these barely drunk drivers are barely still safe, but it suggests that perhaps standards could be loosened.

Its also worth noting that while the study showed cell drivers as performing much worse than drunk drivers, its conclusion states "the data presented in this article are consistent with this estimate [that cell phone danger is the same as BAC 0.08 danger]...the impairments associated with using a cell phone while driving can be as profound as those associated with driving with a blood alcohol level at 0.08". I have trouble seeing an honest way to interpret this conclusion, which seems to seriously misstate the results. Perhaps the author's don't want to be seen as saying its OK to drive drunk?

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BTW, I have emailed paper

BTW, I have emailed paper co-author David Strayer asking why their conclusion appears to misstate their results. I quote the results and conclusion, then say:

It does not appear to be that your results were consistent with the Redelmeier and Tibshirani estimate. Your results did not show the hazards were similar. They showed that the cell phone risks were much greater. Your statement that the impairments "can be as profound" suffers the same problem. You show A to be much riskier than B, then say that "A may cause impairment as profound as B". It appears to me that the current conclusion significantly misstates your results, but perhaps I have misunderstood something.

If you wish to reference the previous study, a statement like "The data presented in this article confirmed Redelmeier and Tibshirani's finding that cell-phone use is associated with increased hazard" seems much more accurate. And replace "can be as profound" with "appears to be more profound" (since that's what your data says).

Personally, I find the data showing lack of increased accident rate among drivers w/ 0.08 BAC just as interesting and useful as the data about the danger of cell phones, and feel it belongs in the conclusion as well. But I can see why that might be too politically incorrect. If you were interested in exploring that area, you could have groups with different BAC levels use the simulator. Not only would this produce a measure of impairment with respect to BAC, but you could find the BAC level at which increased risk of accident was the same as for cell-phone users. This would enable a more accurate comparison of the two hazards.

Nice catch, Patri. I also

Nice catch, Patri. I also agree that the BAC info is at least just as interesting -- if not more so.

I am not sure when the BAC limits became so low in I believe most of the States now. I suppose that's how a lot of laws happen, people not paying attention. What a bonanza for the insurance companies.


Using a hand-held mobile

Using a hand-held mobile phone whilst driving a motor vehicle was made illegal in the UK last year, with potential fines of between £1,000 ($1,500) and £2,500 ($3,750) for drivers caught using a hand-held device with so much as their vehicle's engine started, if convicted in a court of law. Since the introduction of the law and the government's massive propaganda campaign many British drivers have become visibly paranoid about answering their phones in their cars and sales of in-car hands-free kits have soared (since it is legal to talk in a car via such a device).

The issue is clearly one of drivers' attention being divided between multiple tasks thus reducing drivers' concentration on driving and observing traffic and it is already illegal in most Western nations to drive a motor vehicle in a dangerous manner or without paying proper attention to the road, whether or not intoxicated or distracted by a conversation, which makes a mockery of the practice of defining 'special cases' where a driver might not be paying as much attention to the road as he usually would be - such as after having consumed a certain set level of alcohol.

Dangerous driving is dangerous driving: Some people drive particularly dangerously after having a few drinks or whilst engaged in a conversation with a passenger or on a mobile phone and others seem to drive dangerously all the time so in the interests of simple and consistent law it makes sense that a drink-driver's crime is 'dangerous driving' rather than 'driving under the influence'.