Freakonomics author turns attention to bike helmet compulsion
New York Times blog piece dissects academic paper on unintended consequences of compulsion
An academic paper outlining how making it compulsory for young cyclists to wear helmets, although reducing the number killed in accidents on their bikes can unintentionally lead to a fall in the number cycling in the first place, has attracted the attention of one of the co-authors of the bestselling book Freakonomics.
The book, which has sold more than 4 million copies worldwide since its publication in 2005, is a collaboration between University of Chicago economist Steven Levitt and New York Times journalist Stephen J Dubner.
Subtitled “A Rogue Economist Explores the Hidden Side of Everything,” the book puts a popular spin on the normally dry subject, its authors using statistics and economic theory to answer questions such “why do drug dealers still live with their moms?” (the reason: dealing crack cocaine isn’t as lucrative nor as glamorous as Hollywood movies or rap artists might lead you to believe).
Earlier this week, in the Freakonomics blog on the website of The New York Times, Dubner turned his attention to a research paper published by Christopher S. Carpenter and Mark Stehr of the University of California, Irvine, called ‘The Intended and Unintended Effects of Youth Bicycle Helmet Laws’.
During their research, the paper’s authors found that besides confirming earlier studies that had linked compulsory youth helmet laws, in force in more than 20 states across the USA, with a reduction in the number of cyclists in the target group who were killed or seriously injured, such laws also “significantly reduced youth bicycling,” a finding confirmed by both the responses of parents surveyed, and youths themselves.
Dubner highlighted that because the relevant laws apply in only 21 states – most of them, coincidentally on the East or West coasts, as evidenced by a rather arresting graphic in the research paper – which include more than half the national population in the relevant age groups, Carpenter and Stehr were in the happy position of being able to easily compare the situation in those states with others which have no such legislation.
Their first finding was that where helmet-wearing for under-16s was compulsory, fatalities as a result if cycling accidents were 19% lower than elsewhere, with levels of wearing the protective headgear between 29% and 35% higher.
But that coincided with what they described as “robust evidence for an unintended and previously undocumented mechanism: helmet laws produced modest but statistically significant reductions in youth bicycling participation of 4-5 percent.”
Although the academics’ findings may be “previously undocumented” in terms of the US, certainly there is plenty of evidence from elsewhere that compulsion leads to lower participation; whenever the issue is raised in the UK, opponents cite the experience of Australia, where levels of cycling fell by up to 90% among teenage girls in Sydney when helmets were made compulsory there.
Added to that is the fact that studies also show that the more people who cycle, the lower the rate of bike riders killed or seriously injured due to a “safety in numbers” effect, evidenced by the low casualty rates in cycle-friendly cities such as Copenhagen or Amsterdam where, perhaps not coincidentally, helmet wearing is much less prevalent than in other countries where cyclists are more at risk.
It’s also something that regularly crops up on the political agenda here, albeit without ending up in the Queen’s Speech. In October 2007, Peter Bone, Conservative MP for Wellingborough, proposed in a motion before Parliament that a bill be introduced to make bicycle helmets compulsory for anyone aged 17 and under, although his plans got no further.
Going back to Carpenter and Stehr’s study, the pair put forward three main reasons why youths might abandon cycling altogether when forced to wear a helmet. First, they cited cost – not just the expense of buying a lid in the first place, but also in terms of the damage done to a teenager’s credibility, with respondents claiming that they made them look like “geeks” or “nerds.” As a result, they chose not to ride a bike, instead finding something else to do with their time.
Secondly, and here’s a real piece of applied economic theory for you, the researchers stated that, based on principles established by a 2001 study on teenage smoking by Gruber and Zinman, “there is evidence that youths have suboptimally high discount rates such that some youths might place too little weight on the expected gain in future utility from the prevention of injury or death relative to the costs of wearing helmets today,” which you or I might better understand as “live fast, die young.”
Applied to smoking, that principle means that a teenager will puff away on a cigarette today without worrying about contracting lung cancer 20 or 30 years down the line; applied to compulsory helmet wearing, it results in abandoning cycling altogether, and thereby missing out on the health benefits it would bring throughout their lifetime.
Thirdly, making the wearing of bike helmets compulsory, which in itself requires the purchase of a helmet, makes competing activities such as skateboarding, where there is no such requirement, cheaper.
Dubner describes these conclusions as “perfectly sensible,” but posits a couple more of his own, saying that helmets may be viewed as “a hassle,” presumably due to having to remember to put it on in the first place, the possible discomfort of wearing one, and then having to carry it around when off the bike.
Also – and this suggestion will be familiar to anyone following the cycle safety debate in the UK – Dubner believes that compulsory helmet laws reinforce the idea that cycling is a dangerous activity. As a result, he maintains, “a certain kind of parent develops a bias against it, and no longer encourages his or her kids to ride a bike — or, perhaps, never even bothers to buy the kid a bike.”
And that brings us back to Freakonomics, which devoted a chapter to how the best intentions of parents could actually result in their children being exposed to greater risk, which Dubner and Levitt examined by posing the question, “Which is more dangerous: a gun or a swimming pool?”
Imagining the scenario of a parent who won’t let their child play at a friend’s house due to the presence of firearms, but will let them visit a house where there is a swimming pool, the authors cited statistics that showed that each year in the US, while one child dies in a gun-related accident for every million guns, one drowns for every 11,000 swimming pools. That, they claimed, meant that a child is around 100 times more likely to die in an accident at a pool than in one involving a firearm.
Returning to cycle helmet compulsion, Dubner concludes: “Whatever the case, a downturn in bike ridership may strike some people as a grievous strike against the American character. On the other hand, it’s great news for the likes of Nintendo, Sony, and Microsoft.”
That it may be – although surely it’s only a matter of time before health and safety campaigners start lobbying for children playing games on the Nintendo Wii to start wearing helmets to protect themselves from injury?