CTT introduce compulsory helmets and front lights

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Jdsk
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Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

Mike Sales wrote: 18 Jan 2022, 4:02pm
Jdsk wrote: 18 Jan 2022, 1:17pm Isn't risk compensation about how people behave? Not about their knowledge or beliefs?
The point is that peoples' beliefs (whether well founded or not) about risks and rewards inform their behaviour.
Of course they do. But some other aspects of behaviour can't be easily linked to beliefs.

And what affects their safety and that of others is their behaviour.

And it's a lot easier to study behaviour than beliefs.

Jonathan
Mike Sales
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Joined: 7 Mar 2009, 3:31pm

Re: CTT introduce compulsory helmets and front lights

Post by Mike Sales »

Jdsk wrote: 18 Jan 2022, 4:05pm
Mike Sales wrote: 18 Jan 2022, 4:02pm
Jdsk wrote: 18 Jan 2022, 1:17pm Isn't risk compensation about how people behave? Not about their knowledge or beliefs?
The point is that peoples' beliefs (whether well founded or not) about risks and rewards inform their behaviour.
Of course they do. But some other aspects of behaviour can't be easily linked to beliefs.

And what affects their safety and that of others is their behaviour.

And it's a lot easier to study behaviour than beliefs.

Jonathan
Like the bloke who looked under the lampost for his keys, because the light there was better?
If we do not accoiunt for how changing the conditions may change the behaviour our well intentioned reforms may fail to work.
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Jdsk
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Joined: 5 Mar 2019, 5:42pm

Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

Mike Sales wrote: 18 Jan 2022, 4:08pmLike the bloke who looked under the lampost for his keys, because the light there was better?
If we do not accoiunt for how changing the conditions may change the behaviour our well intentioned reforms may fail to work.
Is the point that you're making that risk compensation can never be studied scientifically, or only that some or all previous studies have some limitations?

Thanks

Jonathan

PS: IMV it should be looked for, and sometimes it will be found and sometimes it won't.
mattheus
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Location: Western Europe

Re: CTT introduce compulsory helmets and front lights

Post by mattheus »

Jdsk wrote: 18 Jan 2022, 4:05pm
Mike Sales wrote: 18 Jan 2022, 4:02pm
Jdsk wrote: 18 Jan 2022, 1:17pm Isn't risk compensation about how people behave? Not about their knowledge or beliefs?
The point is that peoples' beliefs (whether well founded or not) about risks and rewards inform their behaviour.
Of course they do. But some other aspects of behaviour can't be easily linked to beliefs.

And what affects their safety and that of others is their behaviour.

And it's a lot easier to study behaviour than beliefs.

Jonathan
We are talking about studying humans, not monkeys. One advantage of this is that we can very often determine what they think and/or believe*, AS WELL AS study their behaviour.

Hence we know a lot more about risk-compensation in humans than in monkeys. Hooray for Science! :idea: :P

*many methods are available. Asking them questions, for example.
Jdsk
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Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

mattheus wrote: 18 Jan 2022, 4:18pm
Jdsk wrote: 18 Jan 2022, 4:05pm
Mike Sales wrote: 18 Jan 2022, 4:02pm The point is that peoples' beliefs (whether well founded or not) about risks and rewards inform their behaviour.
Of course they do. But some other aspects of behaviour can't be easily linked to beliefs.

And what affects their safety and that of others is their behaviour.

And it's a lot easier to study behaviour than beliefs.
We are talking about studying humans, not monkeys. One advantage of this is that we can very often determine what they think and/or believe*, AS WELL AS study their behaviour.

Hence we know a lot more about risk-compensation in humans than in monkeys. Hooray for Science!

*many methods are available. Asking them questions, for example.
Their beliefs should be studied.

For these purposes would it matter what their beliefs were if the effects weren't detectable in their behaviour?

Thanks

Jonathan
Mike Sales
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Re: CTT introduce compulsory helmets and front lights

Post by Mike Sales »

Jdsk wrote: 18 Jan 2022, 4:13pm
Mike Sales wrote: 18 Jan 2022, 4:08pmLike the bloke who looked under the lampost for his keys, because the light there was better?
If we do not accoiunt for how changing the conditions may change the behaviour our well intentioned reforms may fail to work.
Is the point that you're making that risk compensation can never be studied scientifically, or only that some or all previous studies have some limitations?

Thanks

Jonathan

PS: IMV it should be looked for, and sometimes it will be found and sometimes it won't.
As you know doubt know, not all real phenomena are suseptible to study by the scientific method.
I am mainly interested in the application of the theory to road safety, and I believe that making drivers less and less vulnerable to the results of their misjudgements has increased road danger for others.
People cannot be made safer than they want to be, and if risks are decreased then rewards weigh more heavily in the balance.
I think you might find John Adams's Risk interesting. It goes into the subject in much more depth than a forum post can.

http://www.john-adams.co.uk/wp-content/ ... K-BOOK.pdf
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Jdsk
Posts: 24639
Joined: 5 Mar 2019, 5:42pm

Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

PS: In the unlikely possibility that anyone has missed it here's a recent commentary on studies of risk compensation (in humans):
https://www.bmj.com/content/370/bmj.m2913

Jonathan
Jdsk
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Joined: 5 Mar 2019, 5:42pm

Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

Mike Sales wrote: 18 Jan 2022, 4:26pm
Jdsk wrote: 18 Jan 2022, 4:13pm
Mike Sales wrote: 18 Jan 2022, 4:08pmLike the bloke who looked under the lampost for his keys, because the light there was better?
If we do not accoiunt for how changing the conditions may change the behaviour our well intentioned reforms may fail to work.
Is the point that you're making that risk compensation can never be studied scientifically, or only that some or all previous studies have some limitations?

PS: IMV it should be looked for, and sometimes it will be found and sometimes it won't.
As you know doubt know, not all real phenomena are suseptible to study by the scientific method.
I am mainly interested in the application of the theory to road safety, and I believe that making drivers less and less vulnerable to the results of their misjudgements has increased road danger for others.
People cannot be made safer than they want to be, and if risks are decreased then rewards weigh more heavily in the balance.
I think you might find John Adams's Risk interesting. It goes into the subject in much more depth than a forum post can.

http://www.john-adams.co.uk/wp-content/ ... K-BOOK.pdf
Yes. It's very interesting and thought provoking. It's also a monograph from more than 20 years ago.

Can it really be the case that our knowledge hasn't improved since then? Or that any piece of work that has never been peer reviewed can provide better evidence than a systematic review of the literature?

Jonathan
Jdsk
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Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

Mike Sales wrote: 18 Jan 2022, 4:26pmAs you know doubt know, not all real phenomena are suseptible to study by the scientific method.
I don't know anything of the sort.

And risk compensation can be studied. And has been.

And if you think that it isn't susceptible to study then isn't the logical position to make no claims about it?

Thanks

Jonathan
drossall
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Re: CTT introduce compulsory helmets and front lights

Post by drossall »

To be honest I am getting confused about who is arguing what here. But beliefs are central to any argument of risk compensation. People proceed on the basis of what they believe to be true. Since the level of risk is itself under debate in most relevant scenarios, and anyway none of us carries around a table of accident rates at all the locations through which we are passing on a given journey, it's impossible for us to proceed solely on the basis of facts anyway.

But any idea that risk compensation completely negates the benefits of any safety measure is ridiculous. I think I mentioned already the success of shared spaces schemes such as in Poynton. In risk compensation terms, those work because drivers over-estimate the risks of the change, and over-compensate by taking fewer risks themselves, so the net effect is very positive. That again, though, is an example of drivers getting the assessments wrong and failing to compensate precisely. I don't see why it can't happen in reverse as well.

I believe a more typical outcome to be that safety measures produce benefits, but not as great as expected, because road users take some of the benefits as performance gains (by taking more risks). For example, the effect where a road is straightened; risk reduces, so vehicle speeds increase, and there are more crashes down the road at the next bad bend. That may well still be fewer crashes overall though. With seat belts, I'm not aware that anyone claims anything but a reduction in casualties among car occupants - although there have been claims that these are negated by increases in injuries to pedestrians and others, presumably because drivers took the benefits as performance increases and drove faster. That said, belts came in by stages, and you wouldn't expect as clear an effect from a change to require rear seat belts, because the driver is not directly affected.

In any case, getting back to helmets, my perception is that the whole thing was the other way around. I did not encounter risk compensation, rotational injuries, or any other effect as a reason not to wear helmets. I first came across them as competing attempts to explain why helmet wearing was not producing the expected level of benefits at a population level. I think the first paper I saw showing negative effects overall was in the Journal of Products Liability in 1988, although memory could be playing tricks. Now of course, since then, there have been much more positive results as well as some more negative ones, but it's from that kind of result that risk compensation came into the debate, at least as I remember it.
Jdsk
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Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

drossall wrote: 18 Jan 2022, 6:05pmIn any case, getting back to helmets, my perception is that the whole thing was the other way around. I did not encounter risk compensation, rotational injuries, or any other effect as a reason not to wear helmets. I first came across them as competing attempts to explain why helmet wearing was not producing the expected level of benefits at a population level.
That is an important question. And if we'd try and answer specific questions of that type and not mix them up with each other we might be able to reach some consensus about what's currently known and what isn't.

Jonathan
Jdsk
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Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

drossall wrote: 18 Jan 2022, 6:05pm To be honest I am getting confused about who is arguing what here. But beliefs are central to any argument of risk compensation. People proceed on the basis of what they believe to be true. Since the level of risk is itself under debate in most relevant scenarios, and anyway none of us carries around a table of accident rates at all the locations through which we are passing on a given journey, it's impossible for us to proceed solely on the basis of facts anyway.
I'm arguing that risk compensation might be relevant and should be studied to see if it's happening or not and how big the effect is.

And that behaviour is what really matters in reducing harm to ourselves and to others.

And that beliefs might affect that behaviour. But that many of the possible effects won't be rational consequences of things that we would normally call "beliefs" but better described as subconscious behaviour.

Jonathan
Jdsk
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Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

drossall wrote: 18 Jan 2022, 6:05pmBut any idea that risk compensation completely negates the benefits of any safety measure is ridiculous.
I wouldn't use that word. But I would describe the belief that it inevitably happens in all circumstances or inevitably negates all of the benefits as dogma.

We'll find out when and where and how much it happens by studying it. As is happening already.

Jonathan
Steady rider
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Re: CTT introduce compulsory helmets and front lights

Post by Steady rider »

https://www.bmj.com/content/321/7268/1055
This could provide an example to consider, admissions rate increasing and head injuries rate reducing.

The article 'Trends in serious head injuries among cyclists in England: analysis of routinely collected data' was lacking in data on changes in cycling levels between 1991 and 1995. It provided hospital admissions data for April 1991 to March 1995, including 8678 in 1991-2 to 8781 in 1994-5 and the number with head injury as primary diagnosis fell from 3,393 to 2,571, reduced 24.2%. Great Britain traffic details on mileage cycled reported changes from 1991 to 1995, from 3.167 billion miles (Bm), 2.919Bm, 2.484Bm, 2.484Bm, 2.546Bm. Approximately 86% of the population lives in England. Estimating admissions per Bm, 1991-92, 8678/2.67 = 3262, 1994-95, 8781/ 2.15 = 4084, increased 25%. For head injuries per Bn miles, 1991-92, 3393/2.67 = 1271, 1994-95, 2571/ 2.15 = 1196, reduced 5.6%. Indications are that children cycling reduced between 1991 to 1995 and helmet wearing increased. Total GB road fatalities 4568 in 1991 reduced by 20% to 3650 in 1994.
Part of the conclusions mentions 'Our findings indicate that cycle helmets are of benefit both to children and, contrary to popular belief, to adults.' With admissions increasing relative to cycling levels by 25%, it shows the conclusions are not warranted.
Jdsk
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Re: CTT introduce compulsory helmets and front lights

Post by Jdsk »

Steady rider wrote: 18 Jan 2022, 8:18pm https://www.bmj.com/content/321/7268/1055
This could provide an example to consider, admissions increasing and head injuries reducing

....
There is no point in cherrypicking an individual paper from over 20 y ago when systematic review methods are now so clearly established.

But what question were you attempting to answer in that post, please?

Thanks

Jonathan
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