Stephen Dubner reports on an observational study of bike helmet laws, a study by Christopher. Carpenter and Mark Stehr that compares bicycling and accident rates among children among states that did and did not have helmet laws. In reading the data analysis, I'm reminded of the many discussions Bob Erikson and I have had about the importance, when fitting time-series cross-sectional models, of figuring out where your identification is coming from (this is an issue that's come up several times on this blog)--but I have no particular reason to doubt the estimates, which seem plausible enough. The analysis is clear enough, so I guess it would be easy enough to get the data, fit a hierarchical model, and, most importantly, make some graphs of what's happening before and after the laws, to see what's going on in the data.
Beyond this, I had one more comment, which is that I'm surprised that Dubner found it surprising that helmet laws seem to lead to a decrease in actual bike riding. My impression is that when helmet laws are proposed, this always comes up: the concern that if people are required to wear helmets, they'll just bike less. Hats off to Carpenter and Stehr for estimating this effect in this clever way, but it's certainly an idea that's been discussed before. In this context, I think it wouldb useful to think in terms of sociology-style models of default behaviors as well as economics-style models of incentives.
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Did they show a causal effect? In other words, could it be that people who don't like bikes (for many reasons I guess, such as being dangerous) discourage biking and also create bike-helmet laws.
anecdotally, yes. I bike less because of helmet laws. I appreciate that the intent of such laws is for my own good, but I am fully insured for the moment. it's no one else's issue. not the cop who gave me the ticket or that annoying person who yells 'wear a helmet!' at me.
I don't mind laws that protect me from other people's malice, that's what they are there for. It is not up to government to protect me from myself.
there are however a number of cyclists whose safety gear should include a straitjacket. and a good reminder of the rules of the road. (drivers too.)
The perception of bicycling as a particularly hazardous activity requiring protective laws precedes actual laws.
Profit is to be made by fear mongering and marketeering. Look, $2 of plastic that retails for $200.
I have ridden >50K miles without damaging a helmet.
Look to the paper, SC will have a mandatory helmet law soon.
The conspiracy of ignorance masquerades as common sense.
Doug: You can buy a bicycle helmet for a lot less than $200.
A lot less than $200, indeed. There was a cost-benefit analysis done on the New Zealand helmet legislation, that used NZ$19.95 as the cost per helmet (Taylor and Scuffham, 2002; http://injuryprevention.bmj.com/content/8/4/317.full). They concluded that even at that price point, the cost of the helmets substantially outweighed the cost of treating the avoided injuries (for teenagers and adults).
I have done a back-of-envelope calculation, using UK Dept of Transport estimates of the proportion of deaths that helmets would prevent, and their estimate of cyclist-kilometres per fatality. Cycling approximately 4,000km per annum, I could expect a helmet to save my life once in 50,000 years.