Cellphone crash risk may be overplayed

2011-12-13 14:30

Detroit - The increased risk of having a car crash attributed to people using their cellphones while driving may have been overestimated in some past studies, a US analysis said.

So-called "distracted driving" has become a big public health issue in recent years, and the majority of US states now ban texting behind the wheel. A handful prohibit drivers from using handheld cellphones at all.

But studies have reached different conclusions about how much of an added crash risk there is, and a recent analysis by researchers at the Wayne State University School of Medicine in Detroit found that two influential studies may have overestimated the risk.

Lead author Richard Young wrote in the journal Epidemiology that the method of two studies on the issue - one 1997 study in Canada, and another from Australia in 2005, which said that cellphone use while driving raised the crash risk four-fold - may have posed problems.

Control window

The studies recruited people who had been in a crash, and then used their billing records to compare their cellphone use during the time of the crash with their cell use during the same time period the week before, a so-called "control window".

"Earlier ... studies likely overestimated the relative risk for cellphone conversations while driving by implicitly assuming that driving during a control window was full-time when it may have been only part-time," he wrote.

Such "part-time" driving would necessarily cut the odds of having a crash, and possibly reduce people's cellphone use, during the control window - and make it seem as if cellphone use is a bigger crash risk.

The two studies asked people if they had been driving during the control window, but they did not account for part-time driving.

Young and his team used GPS data to track day-to-day driving consistency for 439 drivers over 100 days. The days were grouped into pairs: day one was akin to the "control" days used in the earlier studies, and day two the equivalent of the "crash" day.

Statistically insignificant

Overall, there was little consistency between the two days when it came to driving time. When he looked at all control windows where a person did some driving, the total amount of time on the road was about one-fourth of what it was during a "crash" day.

If that information was applied to the two earlier studies, Young estimates, the crash risk tied to cellphone use would have been statistically insignificant - and may help explain why some earlier studies have not linked cellphone use to an increased crash risk.

Fernando Wilson, an assistant professor at the University of North Texas Health Science Centre who was not involved in the analysis, said that the two earlier studies may well have overstated the risk.

But a number of other studies designed in different ways suggest that cellphone use - and especially texting - is indeed hazardous on the road, he added.

In his own study published last year, Wilson looked at information from a government database tracking deaths on US public roads. After declining between 1999 and 2005, deaths blamed on distracted driving rose 28% between 2005 and 2008.

"In wider policy, I don't think this study is going to change the conversation about distracted driving. Most of the conventional thinking is that we need to do something to reduce it," he told Reuters Health.

  • Kyle - 2011-12-13 14:43

    And these people get paid for this crap.

      procold2 - 2011-12-13 15:06

      sounds like one of our gov's studies,im sure there are more important issues to do an analysis.

      piet.strydom - 2011-12-13 16:03

      What has happened to common sense?

      Sheda - 2011-12-13 19:47

      Yes Kyle and now we need a study (a proper one) on the hazards of smoking. 40 years ago EVERYONE smoked and most died from heart attacks. Today people are dying from cancer and smoking is blamed even though half the amount smoke. You see you can tax smokers, like global warming - (it is a load of crap)

  • smahlaba - 2011-12-13 14:44


  • Anthony - 2011-12-13 15:02

    and your point is?

  • Gavin - 2011-12-13 15:16

    Most people shouldn't even be allowed to walk around a shopping center pushing a trolley, now you want them to pilot a one tonne bomb while gossiping on the phone ? It amazes me that people will spend a fortune on a car, but won't spend a few bucks on a hands free kit...

      piet.strydom - 2011-12-20 15:06

      The problem is not the hands, it is the attention deficit....

  • DieSeL - 2011-12-13 15:41

    In SA people cant even drive to start off with. Add a cellphone into the mix and you have disaster! Probably half of our drivers on the road bought their licenses! Even if a person can drive and use a cellphone without causing a crash, they end up causing other problems. Like slowing down because they are busy on the phone and that results in a backup of traffic. I've seen people suddenly brake when there are no cars around them. When i pass i see they busy on the phone...

  • David Skea - 2011-12-13 15:41

    This shouldn't even be up for debate. No phone contact what do ever whilst driving.

      Shira Bacher - 2011-12-13 16:07

      Shira bacher

      Shira Bacher - 2011-12-13 16:08

  • Gregory Jurgens - 2011-12-13 15:47

    The only crash is the news 24 iPhone app.

  • Andre - 2011-12-13 15:57

    Agree. It was and still is overplayed. Isn't it worse having to follow a GPS or a drink in your hand while driving - drink as in non alcholoc beverage?

      Rohin - 2011-12-13 16:34

      Andre I don't agree. If your'e fiddling with your GPS, then yes, but if you're simply following it or holding a drink, you don't have to take your eye off the road as you would to if you're busy SMSing , BBMing etc - Most mistakes I see on the road, and by this I don't mean simply arrogant or aggressive driving is as a result of distraction and using your phone falls into that category.

  • tebogo.lesabane - 2011-12-13 16:03


  • UweK - 2011-12-13 16:32

    ah a bikini... what it shows is interesting, what it hides is vital

  • Robsschele - 2011-12-13 16:53

    Normally we drive bad but with cellphones it's worse. One of our safety rules on site (construction) was not to walk around while you speak on your cellphone. Stand to the side and avoid walking. You can quite easily walk in front of a heavy earthmoving machine.

  • mike.clery - 2011-12-13 18:53

    Haven't they noticed how people drive while talking on the phone? Wandering across lanes, creeping along, not pulling away from green lights, etc. Clearly the vast majority of people can't talk on the phone and drive at the same time, hands free kit or not.

      Charles - 2011-12-14 06:07

      mike, good point. The other day, a guy driving his 4x4, stopped for the red light, rattling away on his cellphone. Waited for me to pull away on my green light, and as i was half way, saw him pull away too, through his red light. I checked on the rear view mirror as he went on, obviously thinking he was at a 4 stop street. A number of vehicles behind mine saw this and just stopped,for him to cross. What's funny, is that not a single hooter was used.

  • ludlowdj - 2011-12-14 12:54

    If my years in service to the sate have taught me anything its is that any study can be manipulated to reflect the desired result. This is a used by governments internationally to influence the man on the street into believing what he is told to believe and to assist government to reach its own objectives without to much public pressure. perfect examples are the hundreds of smoking studies which were done not to even mention the McPherson report which found the British Police to be racist.

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