I’d like to know what’s wrong with all the studies using different methodologies that find a link. Intuitively I find that using a hand held in a car is distracting at least when I’m dialling. It’s all in the paper from the looks of it, but I won’t get round to reading it and satisfying my curiosity for a while yet. If any Troppodillians get the bug, you can download the pdf file here and if you write it up in comments, you can do all of us curious people a favour.
And the abstract is below the fold.
The link between cell phone use while driving and crash risk has in recent years become an area of active research. The most notable of the over 125 studies has concluded that cell phones produce a four-fold increase in relative crash riskcomparable to that produced by illicit levels of alcohol. In response, policy makers in fourteen states have either partially or fully restricted driver cell phone use. We investigate the causal link between cellular usage and crash rates by exploiting a natural experiment induced by a popular feature of cell phone plans in recent yearsthe discontinuity in marginal pricing at 9 pm on weekdays when plans transition from peak to off-peak pricing. We first document a jump in call volume of about 20-30% at peak to off-peak switching times for two large samples of callers from 2000-2001 and 2005. Using a double difference estimator which uses the era prior to price switching as a control (as well as weekends as a second control), we find no evidence for a rise in crashes after 9 pm on weekdays from 2002-2005. The 95% CI of the estimates rules out any increase in all crashes larger than .9% and any increase larger than 2.4% for fatal crashes. These estimates are at odds with the crash risks implied by the existing research. We confirm our results with three additional empirical approacheswe compare trends in cell phone ownership and crashes across areas of contiguous economic activity over time, investigate whether differences in urban versus rural crash rates mirror identified gaps in urban-rural cellular ownership, and finally estimate the impact of legislation banning driver cell phone use on crash rates. None of the additional analyses produces evidence for a positive link between cellular use and vehicle crashes.