Daily Mail corrected over road safety lies

Road.cc – a cycling website – have nicely pulled-apart the latest distortions printed in the Daily Mail about road safety:

A report in today’s Daily Mail claims to show how a Department for Transport report demonstrates “Why death rates INCREASED in 20mph zones”. It’s one of those articles that makes you sigh wearily, the way you might when faced with a wilfully contrary child…

The DfT-commissioned report entitled “Interim evaluation of the implementation of 20 mph speed limits in Portsmouth”, draws the following conclusion: “Early figures suggest that the implementation of the 20 mph Speed Limit scheme has been associated with reductions in road casualty numbers. The scheme has reduced average speeds and been well-supported during its first two years of operation.”

Fairly unequivocal then. But no, that conclusion comes in stark contrast to the opening line of the Mail’s article which states: “Reducing the speed limit to 20mph in all residential streets does not significantly improve road safety.”…

Brooke’s conclusion seems to have been based on the statistic for people killed or seriously injured (KSI) which the DfT report states rose from an average 18.3 to 19.9 when the figures for the three years before the scheme are compared to the two years of its operation covered by the report.

But as the report clearly explains: “Because the total numbers of deaths and serious injuries of casualties by road user type and cause are relatively low, few inferences about the scheme’s impacts should be drawn from these figures.” In other words, the figures are statistically less significant and are the kind  that could vary from year to year as a result of individual incidents (a triple fatality accident occurred in Portsmouth in the consultation period, for example) or factors such as protracted periods of  wintry weather.

More statistically significant perhaps, is the reduction in slight injuries – a far more common type of accident – which when combined with the KSI figures shows an overall 21% reduction in the total number of accidents. The Mail apparently deems this figure “not significant.”

Go and read the rest here.

5 Comments

  • Nic says:

    The inability of journalists to correctly interpret the results generated from scientific study is extremely depressing.
    My mother-in-law regularly reads the Mail. I recently returned home to find her in hysterics because an article was claiming that aqueous cream was an extremely damaging substance to use on the skin of babies – and she had noticed that I use aqueous cream to bathe my baby son.
    A little research revealed that the main sources of this article were a couple of uncontrolled, questionnaire-based studies run in paediatric facilities which concluded that aqueous cream was nominally worse for dermatological side effects than other emollients and IF NOT USED PROPERLY (i.e. if it was used as a moisturizer rather than as a soap substitute), it could cause irritation in children with a particular susceptibility to certain skin conditions such as eczema.
    On the plus side, she now asks me to check the veracity of any ‘health’ stories in the Mail before she heads off to bother the doctor, so I am now able to make a small, positive contribution to reduce the workload of the NHS! Like Angry Mob, Ben Goldman’s ‘Bad Science’ blog is also an excellent place for me to prepare in advance for any Mail-related damage I might come across on my return home from work – many thanks to you both for making my life easier.

  • SadButMadLad says:

    “In other words, the figures are statistically less significant and are the kind that could vary from year to year as a result of individual incidents (a triple fatality accident occurred in Portsmouth in the consultation period, for example) or factors such as protracted periods of wintry weather.”

    It’s the same arguments to explain why speed cameras don’t work.

    An slight increase in the number of accidents just above the norm causes everyone to think that a location is an accident black spot. So the put the camera in. Accidents go down. The camera proponents say that this proves that cameras work when in actual fact the numbers have just gone back to the norm.

    If cameras really did work natioanally then there would be a noticeable drop in the number of accidents after their introduction. There is no such drop. In fact there has been a leveling out of the number of accidents as the numbers get low enough that they are mostly down to randomness.

  • Meee says:

    I always get annoyed reading, or even just hearing about, these corrections.

    Not because the correction is wrong or because it’s bad, but because it’s essentially pointless. They never reach the people who need to actually read them. The only people who would read the daily mail article and *agree* with it would never, ever find that correction. And the ones that do find it wouldn’t have believed the DM’s original article in the first place.

    It annoys me lots.

  • alienfromzog says:

    Wow,

    It’s not like the Mail to misrepresent statistics is it?

    AFZ

  • Claire says:

    Good for Nic. Same applies to me, partner’s parents read it (skim it more like) and sometimes they say things which show they’ve taken in and believe what they’ve read. Elf’n'safety stories mainly. Good to have the opportunity to say ‘no that’s not quite right’ sometimes and know what you’re talking about.

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