Nearholmer wrote: ↑10 Mar 2025, 10:18pm
Hypothetical is a synonym for “made up”, and one possibly ought to be cautious about publishing made-up numbers, in case anyone is foolish enough to believe that they are real.
The purpose of the diagram is not to prove helmets work, or that they don't work, it's to demonstrate how excluding a relevant part of the data can completely reverse the result. That's what it's intended to do, and that's what it does do.
As an aside, Prof Gerd Gigerenzer researches ways to communicate risk, and which ways are easiest to understand. Here's his example of the right way and the wrong way:
.
.
See which method I've chosen.
Jdsk wrote: ↑11 Mar 2025, 9:46am
Nearholmer wrote: ↑11 Mar 2025, 9:06am
It is better called risk homeostasis.
Ah, yes; please get about renaming it, so that I don’t get confused in future.
Homeostasis means something like
restoring to an optimal state.
Which is exactly what people do. Every (considered) decision people make is by weighing the perceived costs against the perceived benefits.
Nearholmer wrote: ↑11 Mar 2025, 9:31am
Of course we do, both instinctively and consciously. And, sometimes we get it right, and sometimes we get it spectacularly wrong by vastly over-valuing either the risk, or the reward.
What I find odd about the ever-recirculating helmet argument here is that people frequently say “ah …., but wearing a helmet makes people take more risks”, and barely ever say “ah …… but people who have consciously and willingly decided to take risks in return for fun are more likely to wear helmets”.
Or to put the same thing another way: people are likely to change their fun in some way if you confiscate their helmets.
Stevek76 wrote: ↑11 Mar 2025, 11:57am
We can already see that with the way plenty react to the concept of not using a helmet to cycle to the shops vs walking it. Similar actual risk exposure, massively differing popularly perceived risk exposure.
The difference between actual and perceived risk is critical in Risk Compensation/Risk Homeostasis/Moral Hazard. If a person's perception of the benefit of a safety device is greater than the actual benefit they have more motive for changing their behaviour than someone who underestimates the benefit. Therefore, paradoxically, we should expect that people who are utterly convinced helmets work would be less likely to benefit from wearing one than someone who's sceptical about them. Traffic engineers use this: think of the lines across the road on the approach to a roundabout: they get closer to each other as you approach the roundabout to make you feel as if you're not braking as hard as you actually are. Falsely increasing the perceived risk in order to induce a change in behaviour.
People drive faster when they using studded tyres, and they drive faster when they're wearing seat belts, but they clearly overestimate the benefit of the belts and underestimate the benefit of studs, because the studs showed a net benefit, and the belts didn't. This is why you need research to test safety devices, you can't just assume that Risk Compensation will render them useless any more than you can just assume it won't.
Nearholmer wrote: ↑11 Mar 2025, 1:59pmAs with all of this topic, things are complex, potentially conflicting, bordering on imponderable, because different people may wear helmets for different reasons, for instance: knowingly engaging in risky activity, mirroring peers, timidity (risk aversion), compulsion, habit formed during childhood under parental compulsion, etc.
So when some people here, as they do, spot correlations between helmet-wearing and being involved in accidents, then leap to the conclusion that there is a causal relationship in a particular direction, they may be seriously off-beam.
The whole of Adams' book revolves around the explicitly stated premise that people's appetite for risk varies from one individual to another:
"The setting of the thermostat varies from one individual to another, from one group to another, from one culture to another. Some like it hot—a Hell’s Angel or a Grand Prix racing driver for example; others like it cool—a Mr Milquetoast or a little old lady named Prudence. But no one wants absolute zero."
When it comes to debates about making helmets compulsory, and lets face it, that's what all this usually boils down to, which is most practical, a law that applies to everyone based on a population average, or a national test of people's risk taking appetite with a law that applies selectively according to their test result?
pjclinch wrote: ↑11 Mar 2025, 2:48pmYes. A huge amount of "work" is undermined by the simplistic assumption that there are broadly two sorts of cyclists, those who wear helmets and those who don't.
There'll only be one type if some people get their way.
As I said on another thread, there are plenty advocating that helmets should be made compulsory, but I've never yet seen anyone suggest they should be illegal. The current status quo: that they're optional, should be enough to satisfy both camps, but apparently it isn't.
