Originally Posted by
wphamilton
Yet that's what the study bases its conclusion on. At the least, they didn't check against that likely possibility.
There is a logic fail in the conclusion as well. Reduced speed (or greater risk) when taking the helmet off is not synonymous with faster speeds or less risk when putting one on, but that's how they conclude. At least they qualify it with "those who use helmets routinely", yet a mandatory helmet law would be pointless for those who routinely wear helmets while for those who do not (the point of a MHL), no difference in speeds (risk) was observed.
Yes. That's my problem with that study.
Originally Posted by
wphamilton
We are comparing the risk of driving vs cycling to this drug store. That risk when cycling is 3-5 times the risk when driving. Do you disagree?
I don't know. Nor do you. From my estlmates based on the number of deaths, it seems to me that the risk of dying per hour is about the same for driving and riding. I suspect that people spend about the same amount of time transporting themselves whatever mode they use (and travel fewer miles when riding than driving).
Originally Posted by
wphamilton
That what I said, for the case of recreation.
I suspect it's true generally (not just for recreation). People likely tolerate 1-2 hours of regular/daily transportation. If they drive 1-2 hours a day, there's very little chance that they'd choose to ride instead.
Originally Posted by
wphamilton
You may think this is splitting hairs, but risk to a population is not the same as the risk of an activity, and I think that you're making a mistake in conflating the two.
All risk assessment is based on a risk per population. The risk to a specific individual is likely quite different than the overall risk to an "average" person with in a population (the risk is going to be different, too, for different subpopulations).
Originally Posted by
wphamilton
You are adding variables: car-free cyclists will take fewer trips for example, perhaps shorter ones.
Of course, they will take shorter trips.
I suspect that people spend around the same amount of time in transit regardless of the mode. People who cycle ride fewer miles and people who drive drive many more miles.
If you compare risk-per-mile, it biases against cycling because it takes a huge amout of time to match driving miles.
Originally Posted by
wphamilton
Most people aren't going to find it credible to say, for example, cycling is safer because you biked 1.5 miles to Taco Bell instead of driving 15 miles to Burger King.
Mostly because risk-per-mile doesn't make sense.
Originally Posted by
wphamilton
For the activity, hold other things equal. Same purpose for the respective trips, same destination, what is the risk.
The 1.5 mile trip by bike is about the same amount of time as the 15 mile trip by far. As far as I can tell, the risk per hour is about the same. Since you wouldn't really ride the 15 miles, the only way to compare the risks is per hour.