Helmets - split from Hi-Vis discussion

For all discussions about this "lively" subject. All topics that are substantially about helmet usage will be moved here.
Mike Sales
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Helmets - split from Hi-Vis discussion

Post by Mike Sales »

[moderator comment: this thread has been split from viewtopic.php?f=6&t=146797]
Labrat wrote: 5 Aug 2021, 8:05pm Has anyone noticed how the anti hi-viz, anti-helmet brigade have begun to sound sound increasingly like anti-vaccine loons?


You can just see Piers Corbyn and David Icke ranting away about it, can’t you?
No, because those who believe that helmets are very little use, are those who follow the evidence, Funnily enough, David Spiegelhalter, who has been very busy lately, advising us on Covid science, has not found any good evidence for helmet efficacy.

https://www.badscience.net/wp-content/u ... .12.05.png
Why not read this BMJ editorial and come back to us?

Whole countries have gone the helmet route, and are still a lot more dangerous for cycling than Britain, and a whole lot more dangerous than the Netherlands, where few cyclists bother with helmets.
It is very clear what measures save cyclists lives, and it is not helmets.
I always find that the use of "brigade" is a symptom of intolerance of, and usually ignorance of, of any other point of view.

Your intemperate ranting should get this thread moved into the Helmet ghetto.
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?
Labrat
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Re: Radio show on Hi-Vis.

Post by Labrat »

Mike Sales wrote: 5 Aug 2021, 8:22pm those who believe that helmets are very little use, are those who follow the evidence,
*Exactly* what the anti-mask/vaccine nutters claim
Whole countries have gone the helmet route, and are still a lot more dangerous for cycling than Britain, and a whole lot more dangerous than the Netherlands, where few cyclists bother with helmets.
See, same again, remember them going on about Sweden? “Whole countries have avoided lockdown and have fewer Covid deaths than Britain”
Last edited by Labrat on 5 Aug 2021, 8:32pm, edited 1 time in total.
Jdsk
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Radio show on Hi-Vis.

Post by Jdsk »

Mike Sales wrote: 5 Aug 2021, 8:22pmFunnily enough, David Spiegelhalter, who has been very busy lately, advising us on Covid science, has not found any good evidence for helmet efficacy.

https://www.badscience.net/wp-content/u ... .12.05.png
I wouldn't describe Spiegelhalter's (or Goldacre's) views in that way. The editorial is mostly about mandation. In passing he points to possible confounding effects in many of the studies which relate to protection of individuals.

Definitely worth reading. And rereading.

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

Radio show on Hi-Vis.

Post by Mike Sales »

Jdsk wrote: 5 Aug 2021, 8:29pm
Mike Sales wrote: 5 Aug 2021, 8:22pmFunnily enough, David Spiegelhalter, who has been very busy lately, advising us on Covid science, has not found any good evidence for helmet efficacy.

https://www.badscience.net/wp-content/u ... .12.05.png
I wouldn't describe Spiegelhalter's (or Goldacre's) views in that way. The editorial is mostly about mandation. In passing he points to possible confounding effects in many of the studies which relate to protection of individuals.

Definitely worth reading. And rereading.

Jonathan
What he and Goldacre write is that it is uncertain that helmets are any benefit.
In the light of the experience of various countries the vehemence of Labrat is unwarranted.
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?
Mike Sales
Posts: 7860
Joined: 7 Mar 2009, 3:31pm

Re: Radio show on Hi-Vis.

Post by Mike Sales »

Labrat wrote: 5 Aug 2021, 8:27pm
Mike Sales wrote: 5 Aug 2021, 8:22pm those who believe that helmets are very little use, are those who follow the evidence,
*Exactly* what the anti-mask/vaccine nutters claim
Whole countries have gone the helmet route, and are still a lot more dangerous for cycling than Britain, and a whole lot more dangerous than the Netherlands, where few cyclists bother with helmets.
See, same again, remember them going on about Sweden? “Whole countries have avoided lockdown and have fewer Covid deaths than Britain”
Please look at the evidence, and try to avoid making up quotes.
Because you feel a strong emotion on this subject it does not mean you must be right.
Have you read my link?
It makes it clear that helmet sceptics should not be equated to anti-vaxxers.
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: 24478
Joined: 5 Mar 2019, 5:42pm

Re: Radio show on Hi-Vis.

Post by Jdsk »

Mike Sales wrote: 5 Aug 2021, 8:36pm
Jdsk wrote: 5 Aug 2021, 8:29pm
Mike Sales wrote: 5 Aug 2021, 8:22pmFunnily enough, David Spiegelhalter, who has been very busy lately, advising us on Covid science, has not found any good evidence for helmet efficacy.

https://www.badscience.net/wp-content/u ... .12.05.png
I wouldn't describe Spiegelhalter's (or Goldacre's) views in that way. The editorial is mostly about mandation. In passing he points to possible confounding effects in many of the studies which relate to protection of individuals.

Definitely worth reading. And rereading.
What he and Goldacre write is that it is uncertain that helmets are any benefit.
In evidence-based work it's very very unusual to find anything that isn't uncertain. That doesn't mean that there isn't any evidence, it's more about trying to identify confounders and bias and using the language of probability.

Jonathan
Labrat
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Re: Radio show on Hi-Vis.

Post by Labrat »

Mike Sales wrote: 5 Aug 2021, 9:17pm
Labrat wrote: 5 Aug 2021, 9:09pm
Mike Sales wrote: 5 Aug 2021, 9:00pm Labrat, you have also shown that you have not read this thread, but have jumped to your own conclusions, besides dragging in helmets which had not been mentioned.
The thread is not about the efficacy or utility of wearing hiviz on a bike, but about the the social connotations of hiviz.
Plenty of posts above that, however, did refer to the issue - so the point stands,
"Plenty of posts", really. I can only find one.
You don't "cherry pick" even, you provide no evidence at all.
You only give us unfounded abuse.

Evidence? Gladly.

https://www.cochrane.org/CD001855/INJ_w ... or-vehicle
https://www.cochrane.org/CD003438/INJ_i ... d-injuries

I do hope you understand what Cochrane reviews are… but suffice to say that if you don’t accept them, then you might as well be on on the bus with Messrs Icke and Corbyn.
Mike Sales
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Re: Radio show on Hi-Vis.

Post by Mike Sales »

Criticisms of the Cochrane Review.
Principal criticisms of the review are:

The review is not independent. Four of the seven papers selected for inclusion were the work of the reviewers themselves and their data dominate the analysis, comprising 77% of the cyclists on whom the review is based. Furthermore, these four papers are based on only two data sets and have themselves been much criticised for fundamental methodological shortcomings (BHRF, 1068).
Only case-control studies were considered for inclusion, although non-randomised studies of this type are acknowledged to be prone to bias because of the difficulty in controlling for the many independent variables (BHRF, 1052).
The paradox presented by the failure of other types of studies (e.g. whole population and time-series data) to show any benefit from large increases in helmet use - let alone the substantial benefits predicted by the studies reviewed - is left unstated and unaccounted for (BHRF, 1096).
The authors are dismissive of the possibility of risk compensation. However, it has subsequently been demonstrated that child cyclists often ride more riskily and suffer more crashes when wearing a cycle helmet (Mok et al, 2004) and that adults are more likely to ride on busier roads if helmeted (Gregory, Inwood and Sexton, 2003).
Similarly no consideration is given to rotational injuries, which dominate the most serious injuries. Helmets have not been shown to mitigate rotational brain injury and there is evidence they may increase the risk and/or severity of rotational injury.(BHRF, 1039).
Claims are accepted of efficacy for which no plausible mechanism exists (e.g. the prevention of mid-face injuries), where the reviewed data set is too small to make reliable inference (e.g. the result of collisions with motor vehicles), and which would not be possible even if helmets prevented all head injuries (e.g. an increase of 35% in cyclists wearing helmets leading to 66% fewer head injuries).
There is misleading interpretation of 'odds ratio', which is used interchangeably in the review with 'percentage reduction in head injuries'. This exaggerates the predicted benefit of helmets and masks the fact that studies of this type are not truly predictive, being essentially the authors' estimate of what proportion of the observed differences between two groups can be assigned to a single factor. Furthermore, the reviewed paper showing the least benefit from helmets is omitted from computation of odds ratio, thus again exaggerating benefit.
Please read this, especially the last paragraph.
Canadian legislation had minimal effect on serious head injuries

We have both spent a large part of our working lives discussing statistics and risk with the general public. We both dread questions about bicycle helmets. The arguments are often heated and personal; but they also illustrate some of the most fascinating challenges for epidemiology, risk communication, and evidence based policy.

With regard to the use of bicycle helmets, science broadly tries to answer two main questions. At a societal level, “what is the effect of a public health policy that requires or promotes helmets?” and at an individual level, “what is the effect of wearing a helmet?” Both questions are methodologically challenging and contentious.

The linked paper by Dennis and colleagues (doi:10.1136/bmj.f2674) investigates the policy question and concludes that the effect of Canadian helmet legislation on hospital admission for cycling head injuries “seems to have been minimal.”1 Other ecological studies have come to different conclusions,2 but the current study has somewhat superior methodology—controlling for background trends and modelling head injuries as a proportion of all cycling injuries.

This finding of “no benefit” is superficially hard to reconcile with case-control studies, many of which have shown that people wearing helmets are less likely to have a head injury.3 Such findings suggest that, for individuals, helmets confer a benefit. These studies, however, are vulnerable to many methodological shortcomings. If the controls are cyclists presenting with other injuries in the emergency department, then analyses are conditional on having an accident and therefore assume that wearing a helmet does not change the overall accident risk. There are also confounding variables that are generally unmeasured and perhaps even unmeasurable. People who choose to wear bicycle helmets will probably be different from those who ride without a helmet: they may be more cautious, for example, and so less likely to have a serious head injury, regardless of their helmets.

People who are forced by legislation to wear a bicycle helmet, meanwhile, may be different again. Firstly, they may not wear the helmet correctly, seeking only to comply with the law and avoid a fine. Secondly, their behaviour may change as a consequence of wearing a helmet through “risk compensation,” a phenomenon that has been documented in many fields.4 5 One study—albeit with a single author and subject—suggests that drivers give larger clearance to cyclists without a helmet.6

Even if helmets do have an effect on head injury rates, it would not necessarily follow that legislation would have public health benefits overall. This is because of “second round” effects, such as changes in cycling rates, which may affect individual and population health. Modelling studies have generally concluded that regular cyclists live longer because the health effects of cycling far outweigh the risk of crashes.7 This trade-off depends crucially, however, on the absolute risk of an accident: any true reduction in the relative risk of head injury will have a greater impact where crashes are more common, such as for children.8

The impact on all cause mortality, and on head injuries, may be even further complicated if such legislation has varying effects on different groups. For example, a recent study identified two broad subpopulations of cyclist: “one speed-happy group that cycle fast and have lots of cycle equipment including helmets, and one traditional kind of cyclist without much equipment, cycling slowly.” The study concluded that compulsory cycle helmet legislation may selectively reduce cycling in the second group.9 There are even more complex second round effects if each individual cyclist’s safety is improved by increased cyclist density through “safety in numbers,” a phenomenon known as Smeed’s law.10 Statistical models for the overall impact of helmet habits are therefore inevitably complex and based on speculative assumptions.11 This complexity seems at odds with the current official BMA policy, which confidently calls for compulsory helmet legislation.

Standing over all this methodological complexity is a layer of politics, culture, and psychology. Supporters of helmets often tell vivid stories about someone they knew, or heard of, who was apparently saved from severe head injury by a helmet. Risks and benefits may be exaggerated or discounted depending on the emotional response to the idea of a helmet.12 For others, this is an explicitly political matter, where an emphasis on helmets reflects a seductively individualistic approach to risk management (or even “victim blaming”) while the real gains lie elsewhere. It is certainly true that in many countries, such as Denmark and the Netherlands, cyclists have low injury rates, even though rates of cycling are high and almost no cyclists wear helmets. This seems to be achieved through interventions such as good infrastructure; stronger legislation to protect cyclists; and a culture of cycling as a popular, routine, non-sporty, non-risky behaviour.

In any case, the current uncertainty about any benefit from helmet wearing or promotion is unlikely to be substantially reduced by further research. Equally, we can be certain that helmets will continue to be debated, and at length. The enduring popularity of helmets as a proposed major intervention for increased road safety may therefore lie not with their direct benefits—which seem too modest to capture compared with other strategies—but more with the cultural, psychological, and political aspects of popular debate around risk.
I hope that you will see that your intemperate abuse is not warranted, and that it is a bit silly to lump helmet sceptics in with the lunatic anti-vaxxers.
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?
Mike Sales
Posts: 7860
Joined: 7 Mar 2009, 3:31pm

Re: Radio show on Hi-Vis.

Post by Mike Sales »

Jdsk wrote: 5 Aug 2021, 8:29pm
Mike Sales wrote: 5 Aug 2021, 8:22pmFunnily enough, David Spiegelhalter, who has been very busy lately, advising us on Covid science, has not found any good evidence for helmet efficacy.

https://www.badscience.net/wp-content/u ... .12.05.png
I wouldn't describe Spiegelhalter's (or Goldacre's) views in that way. The editorial is mostly about mandation. In passing he points to possible confounding effects in many of the studies which relate to protection of individuals.

Definitely worth reading. And rereading.

Jonathan
It is also about the failings of case controlled studies, which seem to show efficacy, as against whole population studies which do not.
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: 24478
Joined: 5 Mar 2019, 5:42pm

Helmets - split from Hi-Vis thread

Post by Jdsk »

Mike Sales wrote: 5 Aug 2021, 9:47pm
Jdsk wrote: 5 Aug 2021, 8:29pm
Mike Sales wrote: 5 Aug 2021, 8:22pmFunnily enough, David Spiegelhalter, who has been very busy lately, advising us on Covid science, has not found any good evidence for helmet efficacy.

https://www.badscience.net/wp-content/u ... .12.05.png
I wouldn't describe Spiegelhalter's (or Goldacre's) views in that way. The editorial is mostly about mandation. In passing he points to possible confounding effects in many of the studies which relate to protection of individuals.

Definitely worth reading. And rereading.
It is also about the failings of case controlled studies, which seem to show efficacy, as against whole population studies which do not.
Confounders in case control studies were what I was referring to above.

But where do they refer to whole population studies in the context of protection of individuals who choose to wear or not wear helmets rather than in the context of the effects of mandation, please?

Thanks

Jonathan
Mike Sales
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Re: Radio show on Hi-Vis.

Post by Mike Sales »

Labrat wrote: 5 Aug 2021, 9:57pm

See, there we go. “The scientist were all biased”, “the data is flawed”

For “Canadian legislation had minimal effect on serious head injuries” you might as well just write “Sweden didn’t lockdown”

I’m surprised you haven’t blamed “big helmet” yet.
I provide a coherent discussion of the evidence. It is you who merely dismisses any argument which does not agree with your prejudices.

You should read Goldactre on "Big Pharma" in his Bad Science blog.
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?
Labrat
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Joined: 3 Mar 2014, 11:58am

Re: Radio show on Hi-Vis.

Post by Labrat »

Mike Sales wrote: 5 Aug 2021, 9:43pm
I hope that you will see that your intemperate abuse is not warranted, and that it is a bit silly to lump helmet sceptics in with the lunatic anti-vaxxers.

Not really - you’ve just proved the point:


“Standing over all this methodological complexity is a layer of politics, culture, and psychology. Supporters of vaccines often tell vivid stories about someone they knew, or heard of, who was apparently died from not wearing a mask. Risks and benefits may be exaggerated or discounted depending on the emotional response to the idea of a vaccine. For others, this is an explicitly political matter, where an emphasis on helmets reflects a seductively individualistic approach to risk management (or even “victim blaming”) while the real gains lie elsewhere. It is certainly true that in many countries, such as Sweden and Japan, have low Covid rates, even though rates of travel are high and no lockdowns. This seems to be achieved through interventions such as good infrastructure; stronger legislation to protect borders; and a culture of social distancing as a popular, routine, non-sporty, non-risky behaviour.”
Stevek76
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Re: Helmets - split from Hi-Vis discussion

Post by Stevek76 »

Not really sure what you're trying to do there? You suggesting that goldacre is an anti vaxxer?


I take it from this that you are also a big advocate of use of such safety wear when you're travelling as a pedestrian?

2019 GB road safety stats had fatality rates at 35 pedestrians per billion miles walked and 29 cyclists per billion miles cycled...
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Re: Helmets - split from Hi-Vis discussion

Post by pjclinch »

Labrat wrote: 5 Aug 2021, 8:05pm Has anyone noticed how the anti hi-viz, anti-helmet brigade have begun to sound sound increasingly like anti-vaccine loons?
If you're too dim to see the difference between "anti-something" and "not actively pro-something" then you're probably too dim to see that the people you're trying to put down as idiots by and large don't actually exist.
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Re: Radio show on Hi-Vis.

Post by pjclinch »

Jdsk wrote: 5 Aug 2021, 8:29pm
Mike Sales wrote: 5 Aug 2021, 8:22pmFunnily enough, David Spiegelhalter, who has been very busy lately, advising us on Covid science, has not found any good evidence for helmet efficacy.

https://www.badscience.net/wp-content/u ... .12.05.png
I wouldn't describe Spiegelhalter's (or Goldacre's) views in that way. The editorial is mostly about mandation. In passing he points to possible confounding effects in many of the studies which relate to protection of individuals.

Definitely worth reading. And rereading.
It starts off with the two Big Questions, do they help at societal policy and at individual levels. It quickly buries both as "methodologically challenging and contentious"

There are no smoking guns either way.

Pete.
Often seen riding a bike around Dundee...
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