Ah, ok, I'm starting to see a different perspective on helmet use: comparing cities rather than individuals in a city. Perhaps the studies should differentiate

Ah, ok, I'm starting to see a different perspective on helmet use: comparing cities rather than individuals in a city. Perhaps the studies should differentiate these: i.e. comparing accident rates of helmets against non-helmets within each city individually, vs comparing e.g. non-helmet-users in Amsterdam against helmet-users in Berlin. I live in Dublin which, as mentioned in the article, has recently seen marked improvements in cycle safety. Helmet usage here is high but under 50% and seems evenly distributed. I'd be curious to see the stats on what the means for accident rates local to here.