Friday, October 1, 2010

Texting and Fatal Driving Accidents

Text messages sent per month from hand-held phones increased more than 15-fold from 2002 to 2008. Over the same years the percentage of fatalities in which distracted driving was listed as a possible contributing factor increased from about 12% to nearly 16%.

Based on these data, the authors of a recent report speculate that texting while driving may have contributed to 16,000 additional driving fatalities between 2001 and 2007. The claim was reported in the Los Angeles Times and other papers, but is it true?

There are several problems with this report. First, the authors defined a fatality as caused by driver distraction whenever a distraction was merely listed as present. Other factors such as equipment failure, alcohol, or driver age were not considered. Second, distractions are anything that takes the driver’s attention away from driving, including texting or talking on a hand-held phone, reading an on-board navigation system (also increasingly popular these days), reaching for something, eating, drinking, putting on makeup, etc. Searching for street signs or rubbernecking another accident are also distractions. None of these were factored out in this study.

All the report really shows is that text-messaging volumes (in and out of cars) and the number of fatal accidents due to all distractions are both going up. The authors call it a correlation, but so what? A correlation does not prove causation. I’m reminded of the example presented by my thesis advisor years ago of the tight correlation between the rise in the number of telephones in the U.S. and the decline in the incidence of tuberculosis. Do telephones prevent tuberculosis? Hardly.

Is texting while driving a problem? Probably yes. Does this paper convince me that texting while driving has caused 16,000 additional fatalities? Sadly, no.

No comments: