Is cell phone use while driving really so dangerous?

by on August 20, 2007 at 8:00 pm in Economics | Permalink

Natural experiments have their uses.  Saurabh Bargrava reports his joint work with Vikram Pathania:

…we document a 20-30% rise in cellular call volume during the time of the day– 9pm on weekdays– when cell phone providers systematically transition from "peak" to "off-peak" pricing.  We then measure the resulting increase in fatal and non-fatal crashes during this period as compared to weekends and earlier periods which serve as controls.  We find no evidence for a rise in crashes, and estimate small positive upper bounds for the effect size at 9pm (~1% for all crashes, and 2.4% for fatal crashes).

Here is the paper.  Here is a related press release.  You might wonder how this can be reconciled with all those studies showing that talking on a cell phone is as bad as driving drunk.  The authors discuss the other work starting on p.8 and score some good points.  Furthermore get this:

We confirm our
results with three additional empirical approaches–we 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

No, I am not encouraging you to talk on your cell phone while driving, if only because so many of you already talk so much, and besides, what if these guys are wrong?  But science must progress, and in that spirit I report these intriguing results.

zlguocius August 20, 2007 at 8:17 pm

Neat. I wonder whether some of the effect can be explained by the hypothesis that people who tend to wait until after 9pm to make their calls also tend not to make calls while driving (say, because they’re younger than 16).

I guess I’ll go read the paper!

Ray G August 20, 2007 at 8:30 pm

My contention has always been that regardless, it’s just another difficult to enforce law. The kind of person who is so lazy in their daily habits to be a public nuisance with their cell phone, is also a nuisance because they’re changing radio stations, eating a burrito, et cetera.

A catch-all law that provides a driver can be prosecuted for “distracted driving” if they do get in an accident is sufficient. This is because it is the act of talking that distracts the mind so much, regardless of where the eyes are focused. And with those tiny little blue-tooth ear pieces, all a driver does is put the device on their right ear, and chat away.

So bottom line is that it is eventually just another law on the books, right up there with spitting on the sidewalk, and jaywalking.

Shane Milburn August 20, 2007 at 9:07 pm

My initial thought was that of the first comment. Are most of the folks calling at 9:00 waiting around at home to call Mom and Dad, or are they driving around when they think to call?

Personally I never think about calling home after 9:00 unless I’m already at home. I’m not as good of a driver when I’m talking on my cell .

Paul N August 20, 2007 at 9:27 pm

Whenever I get pissed off at someone driving stupidly, as soon as I can see them they’re invariably on a cell phone.

I believe the cell phone effect to be similar to the old person effect: you slow down instinctively to be safer, like you are subconsciously taking into account your decreased attention and compensating.

So, talking on a cell may not make you less safe, but nevertheless there is a great cost to people doing this – they slow everyone else down and make traffic less efficient. Probably this cost is less than the utility of conversations so banning it is probably a bad idea.

Ryan August 20, 2007 at 10:48 pm

Occasionally, statistical robustness is misplaced in policy decisions. Using a sample of one event I have made up my mind. I was hit on my bicycle last week by a cell phone wielding driver who made no effort to look away from his phone as he pulled out into the street.

One cell phone related accident is one to many.

infopractical August 21, 2007 at 1:03 am

Though I’m generally a fan of the Bookings Institute, I think this paper is awful. From the start, there is a chart showing anti-correlation between accidents and cell phone penetration. There is also anti-correlation between accidents and total U.S. beer consumption.

Reasons for lower crash rates include (1) raised ages of drivers in some states, (2) better engineering of cars, (3) better roads, (4) dramatically reduced fraud, (5) better policies on truck driving, (6) toll roads, and (7) the other fourteen thousand factors I didn’t think of first. The use of time as a significant variable in this paper is fatally flawed at best, and at worst suggests an engineering of results.

The paper quickly dismisses large amounts of prior research with a few belittling comments, but without substantial argument. I used to work in the actuarial department of an auto insurance company. We hated that people talked on their cell phones while they drove because, in our own records of crashes with our own clients, it was a huge factor in the crashes. By our estimates, greater than the correlation of alcohol consumption.

That was the late 90′s, and a decade later, it may be that many people have learned to drive better talking on the phone. Maybe. I know for certain that I have become better at looking at the jerks around me doing it, and making space between me and them. Maybe people like me are suppressing the correlation.

I would also be willing to bet that people have started more frequently lying about being on the phone when they crash. I know my company was formulating a way to add points to drivers with phones built into their cars at the time. I don’t know how that went because that was right about the time most car phones were replaced with ordinary cell phones. It’s also true that a person talking on a cell phone when they harm another person is open to both civil AND criminal penalties — so of course the amount of lying has gone up. This paper states that “Disentangling these effects” (of reporting cell phone use to police) is not possible, while completely ignoring an obvious sharp rise in fear of legal responsibility (not to mention higher insurance rates).

And hey, I’m well trained in statistical methods, and I really don’t see how this 9 pm thought experiment demonstrates much of anything. I’ve got to accept a pile of assumptions to think this has anything to do with the drivers who wind up in the most accidents. A late hour like that is about the safest time to drive — a time when relative inattention has the fewest pitfalls.

There is a lot of bullshit language in this article such as “This study can also be linked to…” with basically no qualification. Previous studies are critiqued for small sample sizes, but the total body of data on this issue is enormous, and the insurance companies have been aware of it (from their own unpublished stats) since the mid-90s.

Then there are claims that cell phones might alleviate boredom and fatigue for some drivers. This may be true, but even so, these distance drivers should be categorized differently from the morning/evening commuters and after-school kid drivers. This would in fact mean that for the rest of drivers, the cell phones were actually a cause of higher incidents of crashes. Perhaps it’s rational to allow talking on the cell phones by drivers during off-peak hours only! Who could write a policy paper like this a miss such a suggestion?

I don’t believe a lot of actuaries are shaking their heads up and down when they read this. They’re shaking it side-to-side.

I’ve spotted dozens of other mistakes in this paper, but I don’t intend to document them all in one grand rebuttal. But it’s just plain terrible. It’s one of those papers that makes me start to wonder who has what kind of political motive. The actuarial world will surely ignore it, and rightfully so.

Tyler, you usually spot a piece of crap when you see it. I believe you should reread this paper and take a whiff.

infopractical August 21, 2007 at 1:40 am

It’s not a mistake to lead with the use of a graph that takes time into account as a variable when there are an abundant number of highly published reasons not to do so? That’s not a fallacy? And is a fallacy not a mistake in a policy paper?

The math is all accurately computed, if that’s what you’re saying. And that doesn’t mean much if the assumptions and logic are flawed.

TruePath August 21, 2007 at 2:47 am

This is all very interesting but the question from a policy perspective is why do we single out certain sorts of activity that increases risk for regulation while not others? It’s my sense that these laws have almost nothing to do with cost/benefit analysis and almost everything to do with what people associate with the guy who cuts them off.

Daisy August 21, 2007 at 5:44 am

Truepath, it is certainly a cost/benefit issue, but it’s also a responsibility issue. Automobiles are dangerous, and when people make mistakes, those mistakes affect other people. Like when loaded guns are waved about.

Waving loaded guns is more immediately dangerous, but the overall effects by drivers are far greater. Would you really rather have no laws against drunk driving? How is this any different? Is that really the battle to pick against paternalistic government?

Independent George August 21, 2007 at 9:15 am

I haven’t read the paper yet, but does it isolate the effect of other drivers (who are not using their cell phones) on vehicle crashes? It could very well be the case that the cell-phone users are driving worse, but are compensated for by the skills of other drivers. Or, it could be that drivers talking on the phone compensate for their reduced skills by deliberately driving more slowly and carefully, or only talk on broad stretches of highway which require less attention, or (as suggested above) when they are stuck in bumper-to-bumper traffic.

I recall an episode of Mythbusters devoted to this question; if I recall correctly, talking on the phone had roughly the same effect as a couple beers.

Jonathan August 21, 2007 at 9:32 am

Wow… just about a perfect exemplar of what you need to get an economics paper some attention:
(1) A hot topic
(2) A result at odds with the literature and, to some extent, common sense
(3) Three hot techniques: A natural experiment, difference-in-difference estimators AND regression discontinuity
(4) A hot adviser — David Card
(5) An implication of consistency with optimizing behavior, with an obligatory reference to Peltzman (1975). Admittedly, this one cuts both ways, since showing some behavioral blindspot would be eye-catching as well.

Nathaniel August 21, 2007 at 12:58 pm

I’m not totally up on all the methodology in any of these studies, but I did watch Mythbusters tackle the question. I didn’t like that the cell phone use they used in their experiment was asking questions on a numbers and logic test and requiring the driver to answer, in my experience cellphone use during driving is mostly idle chatter and not brain bending calculation. I’m not saying that this is how any of the scientific research is conducted, just that I was dissapointed by the Mythbusters particual methodology in one episode (but it’s still a great showand I watch whenever I see that it’s on).

ah August 21, 2007 at 1:59 pm

I didn’t read the paper thoroughly, but do they account for two things?

1) Whether the mix of car-based cell use and land-based cell use is the same around 9pm as at other times of the day? I suspect that more people are using phones at home at 9p than at other points in the day (e.g., rush hour). If it differs, that could skew the results.

2) The overall percentage of cell use in cars vs. not cars. If most of the calls around 9pm are from folks at home (intuitively this makes sense–you don’t sit in your car waiting for cheap calling), then won’t the number of calls drown out statistically any increase in accidents?

miltie August 21, 2007 at 2:58 pm

I always knew that the cell-phone industry was behind all the laws banning the use of cell-phones while driving your car so that they could sell more headsets. Driving and talking on your cellphone does not cause accidents!! It’s bunk people!!!! Bunk!! The cellphone users of the world have nothing to lose, but their chains, Cellphone users of the world…..Unite!!!!!

Rob August 21, 2007 at 4:09 pm

Off peak hours for cell phone use start at 7 pm, not 9 pm. No need to bother reading the article with this garbage.
Cell phone use results in an increase in accidents in at least some circumstances, that’s been proved time and again. It can also be shown neurologically with how the brain processes information that talking on a cell phone adversely impacts driving awareness. Goes to show researchers can rig things to achieve the desired result.

ocmpoma August 22, 2007 at 11:19 am

Any research I’ve ever seen on cell phone use while driving compared talking on the phone to not talking on the phone. I’ve seen studies that indicate it’s not holding the phone, but talking, that is so distracting. However, I’ve never seen anything that compared the distraction level of talking on the phone to talking to a passenger or arguing with the moron on the talk radio show. Am I not looking in the right places? It seems to me that for our minds, a conversation with one’s spouse would be just as distracting whether it was local or remote.

(Sorry if this double posts, I didn’t see it go through properly the first time.)

Anonymous August 22, 2007 at 9:49 pm

Man I’m getting tired of this cute-o-nomics stuff.

Rich August 23, 2007 at 8:22 am

“Man I’m getting tired of this cute-o-nomics stuff.”

Hear hear! You can so easily place yourself in the grad student lounge after the seminar: BuddingEconomist1: “You know, *cell phone* prices change over the course of the day.” BuddingEconomist2: “Yo, my brother, someone should get all freak-o wif it.” BE1: “Hey, I got it, sumpin about cell phones and driving!” BE2: “Brilliant!” BE1 and BE2 together: “We gonna be stars y’all…”

sapphire eyes August 29, 2007 at 10:59 pm

Yes. Cell phones are more dangerous than drunk driving. (According to Adam and Jamie of Mythbusters.) I believe it. Hell, I have problems *talking to the person next to me* while I’m driving.

KJ September 16, 2007 at 4:58 pm

“A study released in April 2006 found that almost 80 percent of crashes and 65 percent of near-crashes involved some form of driver inattention within three seconds of the event.” … “The new study found that the most common distraction is the use of cell phones, followed by drowsiness.” -Quoted from the Insurance Information Institute. (

Also, I read an interesting article that stated that drivers talking on cell phones were very similar to drunk drivers; swerving, slow reaction time, less aware of their surroundings, etc.

Even our drivers manuels agree that when it comes to cell phones, your safest course of action would be to pull over to take the call, or “Let It Ring.” (

Thanks for listening!

shanita September 26, 2007 at 5:02 pm

some are dieing from driving and talking on the cell phones by that but can u tell me this do one person die becaues someone was on the phone talking to someone and that person becaues the person on the phone kill them now he or she family is crying becaues he or she is die can u tell me that no you can’t noe can you ok tell me this will you let your kids get and a car with family and they are talking on the phone what would you do can i drive with your kid an the car and on the cell phone

maranda spence October 22, 2007 at 3:07 pm

i am a girl and think that wemon are the worst drivers ever men rock

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driving rox November 30, 2007 at 8:17 am

the guy who sits in front of me is cute.

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sandy June 4, 2008 at 4:26 pm


Preston Meyers August 14, 2008 at 7:20 am

Really, Ray G? You want a catch-all law to incorporate any kind of “distracted driving?” And who is to make the decision on who or what or when you are distracted? Is this something that can be tacked on only after you are in an accident, or can it be as ubiquitous as a “moving violation?”

Think, man! You really want to give police more reasons to write tickets that you yourself would consider unfair if you were to receive one? How about the “moving at a high rate of speed” law which is not at all tied to the area speed limit, e.g. when roads are wet, icy, etc.?

Branndan October 22, 2009 at 9:54 am

You old people are just as bad while using a phone while driving. It’s not always the younger drviers who have accidents while driving. Cuz we actually have experience using our phone while doing other thing unlike most older people. And plus almost all old people who use a phone while driving go 15 below the speed limit and shouldn’t be on the phone in the first place

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Raducu November 15, 2010 at 12:07 pm

Cell phone conversations during driving is very dangerous because you have one of your hands busy and the reactions in case of something comes up in your way split from 100% to 50%.I guess it is much more easier and safier to pull over talk how much you desire and after that you can continue your road trip.Toll Free Numbers

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