Originally Posted by
350htrr
Yes and I agree the 1% is the risk of having an accident where the helmet failed to protect enough to avoid a hospital visit... But what the actual risk of having an accident where head hits the ground is unknown, totally unknown... That's my point.(trying to be)... So what if the actual chance is 5% but I decide that 1% is safe enough and start to not wear a helmet? A 5% compared to 1% is a big difference, we just don't know the actual % number...
1% risk of an accident, with or without a helmet. The "actual" risk with a helmet will be lower, not higher. If the helmet had, say, a 50% chance of helping you in an accident, then it's 1% x 50%, or .5%.
That's the reason I insisted on separating the two probabilities with the other guy. They really are two independent probabilities, and one is a lot easier to put an accurate number to than the other. It's easier to know total accidents, and some estimate of cycling trips or cyclists, than it is to put a number on how much a helmet will help given an accident. Because we have better (but not perfect) data on those. But you have to multiply the two probabilities together in the end.