2 Jun 2014

Risk, preferences and policy

This exchange happened on Facebook:
OP: On your bike, always wear your helmet.

DZ: Sorry to disagree, but helmets (1) cause drivers AND bike riders to take more risks (Pelzman effect), (2) lower ridership (e.g., bike share w mandatory helmets is less spopular), (3) work only when you lunge forward (per US specs set decades ago) not sideways, (4) are no substitute for (a) separated bike paths or (b) good judgment, and (5) reduce "herd protection" (helmet laws reduce the number of bike accidents BUT reduce the number of riders even further, i.e., more accidents/rider b/c riders are more vulnerable).

OP: The literature you refer to David looks at socially optimal equilibrium and whether governments should mandate helmets and seat belts. Those results hold under some assumption on risk preference. I do not believe that literature also considers accident caused by others (who might be wearing helmet or driving cars).

If you look at the individual level, the story is very different. I would have taken the same risk not wearing a helmet. I've been so used at wearing a helmet that the risk I take are not conditional on wearing a helmet. I would probably be at the hospital right now if it was not of my helmet.

Friend 2: Thanks for debunking the anti-helmet rhetoric. It can hurt your head--literally.

DZ: There's no debunking here -- the stats are in the studies. You all are just infra marginal. When in doubt make your best choice over some academic's conclusions, but don't make laws based on your personal choice!