Advice on Helmets, again (was price vs quality)

For all discussions about this "lively" subject. All topics that are substantially about helmet usage will be moved here.
Jdsk
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Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

Steady rider wrote:I know the 0.4 value is not considered significant but is does not mean it has no value.

I asked you twice what it meant. You didn't reply. You tried to avoid the question by asking me how it was calculated.

Please could you now say what value you think it does have.

Thanks

Jonathan
Steady rider
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Re: Advice on Helmets prices vs quality ????

Post by Steady rider »

https://www.simplypsychology.org/p-value.html

The p value of 0.41 is based on statistical assumptions and with helmets other factors may come into consideration.
Jdsk
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Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

Obviously I wasn't asking about what any p value means in a general statistical sense.

I was asking what value you placed on it in the statement that you selectively quoted from the paper that you cited:

Steady rider wrote:https://bmjopensem.bmj.com/content/bmjosem/6/1/e000746.full.pdf
Taking another look at this recent paper, 28 cases, 20 had previous concussions. Bicycling-related concussions leading to postconcussion syndrome in adults’, details ‘The mean duration of PCS for helmet wearers was 22.9 months, and 16.8 months for patients not wearing a helmet at the time of concussion (p=0.41)’

Why did you select this from the whole paper?

Do you think that it is good evidence of a true difference between the two groups in this study?

Jonathan
Steady rider
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Re: Advice on Helmets prices vs quality ????

Post by Steady rider »

Because it could be significant even if the p value is not, 'emphasis could be'. i may need to some research to see if this looks viable.
Jdsk
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Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

Steady rider wrote:Because it could be significant even if the p value is not, 'emphasis could be'. i may need to some research to see if this looks viable.

What research would affect this? At p = 0.41 it isn't possible to reject the null hypothesis.

You drew attention to it because you wanted people to think that it was evidence of a true difference. It isn't.

Jonathan

PS: if anyone is reading this who isn't familiar with this type of statistical test... it's crucial to know that there is a specific meaning of significance (for example with a p value) that is different from its everyday meaning of importance.
Stevek76
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Re: Advice on Helmets prices vs quality ????

Post by Stevek76 »

Campaigning is one thing, desperately shoring up evidence for the obviously bad public health policy that is Australia's helmet laws is quite another.

Given some of the rubbish Olivier manages to get published (eg efforts to dismiss the plummet in cycling rates in aus/nz and to demonstrate, against all reason, that being forced to wear a helmet is not at all a barrier to cycling) I wonder quite how much of a distinction being published/peer reviewed is when it's such a niche subject matter as this.

Such a process takes both time and money, something he clearly has plenty of as well as a supply of willing minions in the form of post grads/docs and I've major concerns over publication and other biases in his own work and any systematic reviews.

Spiegelhalter & goldacre remains a good summary to me, arguing the protective merits of helmets is unlikely to be productive or conclusive. If I'm set upon by a helmet busybody (something that seems to have increased in recent years) it's far easier to simply point of the list of equally risky things they'd think wearing a helmet for was excessive and leave it at that.
The contents of this post, unless otherwise stated, are opinions of the author and may actually be complete codswallop
Jdsk
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Re: Advice on Helmets prices vs quality ????

Post by Jdsk »

Stevek76 wrote:Given some of the rubbish Olivier manages to get published (eg efforts to dismiss the plummet in cycling rates in aus/nz and to demonstrate, against all reason, that being forced to wear a helmet is not at all a barrier to cycling) I wonder quite how much of a distinction being published/peer reviewed is when it's such a niche subject matter as this.

It's very important in helping to grade the levels of evidence. (This is not a statement that peer review is perfect or anything similar.)

On the topic under discussion (injuries and helmets, not mandation) there are now two large recent reviews using the state of the art methods for reviews. They're cited above.

When that is the case it is simply bad practice to repeatedly cite grey literature with lower levels of evidence. And to not identify yourself as the author when you're citing yourself.

We'll come back to whether cherrypicking that data with the p value was a mistake, a deliberate attempt to misinform, or genuine ignorance of the most commonly used method of hypothesis testing. We all make mistakes but I'm not sure which of the other two would be worse from someone who describes himself as having "had more research published on helmets than any other author in the UK".

And the idea that you don't have to do statistical testing because it's about helmets doesn't make sense.

As I wrote in one of the many parallel discussions: it's essential to decide whether you want to use scientific method or not.

Jonathan
Stevek76
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Re: Advice on Helmets prices vs quality ????

Post by Stevek76 »

cycling is by any measure more dangerous than walking.


This is incorrect. The dft published stats rate (per distance traveled) of slight and serious injuries is higher for cycling but the rate of dying altogether is little higher for a pedestrian (35.4 vs 29 deaths per billion miles travelled for 2019)

And I wonder if the cycling miles are underestimated here as well. Mileage by mode is primarily derived from the national travel survey and trips with the sole reason being the trip are not recorded by it, as such not all leisure/sports cycling is captured while casualties from that cycling generally do show up on the stats19 data.

Further rural travel is disproportionality riskier for cycling than walking such as the fatalities within London against TfLs estimates for distance walked and cycled. So if you live in town it's probably safer to cycle to the shops than walk there (depending on what personal weight you assign to being seriously injured vs dying)

Of course, neither is a particularly high risk activity in the grand scheme of things (unless you choose to make it so)

As for the hovding, not entirely convinced of the benefits of that. It's certainly effective, the problem for me is that I only use a helmet when mtbing where spills are not uncommon and a helmet that 'goes off' unnecessarily would be expensive and annoying. Nor would it provide any protection from any undergrowth, occasionally spiky, that tends to dangle over the trails occasionally.
The contents of this post, unless otherwise stated, are opinions of the author and may actually be complete codswallop
ymfb
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Re: Advice on Helmets, again (was price vs quality)

Post by ymfb »

As someone who wears a helmet for skiing, compulsory when motorcycling, hard hat at work not wearing a helmet for cycling would be odd. It’s a requirement at Sportives, which I agree with. For anyone who is involved in h & s and writing risk assessments wearing helmets would be on the PPE list, as would gloves and glasses.

A friend involved in a cycle v cycle accident on a cycle path was in the words of the attending paramedics was saved by wearing a good quality cycle helmet.

Just like when motorcycle helmets became compulsory in 1973 and seat belts in 1983 there were dissenters but the younger generations will consider it the sensible and the older people will either give in, give up or get caught. Not wearing helmets may become socially unacceptable like smoking and drink driving. Arguing about how statistics and scientific reports might be considered will become an irrelevance.
Two wheels preferred.
cycle tramp
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Re: Advice on Helmets, again (was price vs quality)

Post by cycle tramp »

ymfb wrote: 19 Sep 2023, 8:31am
A friend involved in a cycle v cycle accident on a cycle path was in the words of the attending paramedics was saved by wearing a good quality cycle helmet.
Eh?... How the hell can you be in a collision with another cyclist on a cycle path? Both are relative slow moving narrow objects, with complete 180 degree vision and nothing to block any potential sounds which may give a warning of other approaching path users...
..as someone who sometimes doesn't wear a helmet, tje issue isn't the assumption of the paramedic which is unfounded at best, but that the collision actually took place, and that it has been compounded by calling it 'an accident' - as if it was somehow unexpected or not caused by a failing by one or both parties.
It's time to go :-)
Nearholmer
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Re: Advice on Helmets, again (was price vs quality)

Post by Nearholmer »

Certainly round here there are numerous blind bends on cycleways, so plenty of opportunities to crash into other cyclists - I’ve had a couple of near misses and now approach certain bends very cautiously. Also, ‘slow moving’ is often not the case, closing speed could be 30-40mph.

But, stranger than that: last Friday I did a mixed road and bridleway ride and was narrowly missed by another cyclist going the other way on a country lane! I was trundling up a gentle hill, and he came over the crest and down on the correct side of the road, then swung wide, right into my path, to take a turn onto a bridleway on his side of the road. It all happened so quickly that all I could do was holler, which thankfully caused him to brake and tighten his curve. We missed by inches.

If asked, I’m sure he would have said SMIDSY, despite my flashing headlamp and bright orange top!
maximus meridius
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Re: Advice on Helmets, again (was price vs quality)

Post by maximus meridius »

wrong thread, unable to delete.
Last edited by maximus meridius on 19 Sep 2023, 9:59pm, edited 2 times in total.
cycle tramp
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Re: Advice on Helmets, again (was price vs quality)

Post by cycle tramp »

maximus meridius wrote: 19 Sep 2023, 9:32pm This "individual freedom" angle is nonsense.
No, its fact... currently I am enjoying a large amount of individual freedoms. I have the freedom to worship or not, the freedom of expression (within limits) the freedom of movement... and so on and so on... towards the bottom of the list is the 'freedom to ride my bicycle wearing whatever I believe to be suitable'. To say that ''this is not a freedom' merely suggests that we happen to take it for granted, perhaps more than we should do... and certainly to deny that this freedom exists only impoverished our rights.

...most people are not bothered by the idea of compulsory helmet wearing - as much like me sometimes, they wear them..

..but supposing the state or parliament went beyond that, supposing hi-vis became compulsory or a little orange flashing light, or that bicycles had to be painted day-glo green...

..the issue is with compulsory safety measures, is that it never stops - ask any motorcyclist and they will tell you that after the helmet law came in, they then had to protest very hard to stop Peter Bottomley's leg protectors being fitted to new motorcycles and then they had to face air bags and day time riding lights and hi-viz... even now German bikers are I believe currently having to deal with the threat of compulsory glove wearing...

...it is none of your business whether I decide to wear a helmet or not and I don't need to give a response why I don't... nor do I need to seek your permission. in the same way I don't need to defend my musical tastes, or when the time comes, my right to commit suicide to avoid any unnecessary suffering (strangely its okay to put down much loved pets so they don't suffer, but we get all worried that asking for an early death somehow offends a mythical man in the sky)..

..helmets are and always have been a sop or an apology for bad road craft
It's time to go :-)
ymfb
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Re: Advice on Helmets, again (was price vs quality)

Post by ymfb »

cycle tramp wrote: 19 Sep 2023, 6:16pm
ymfb wrote: 19 Sep 2023, 8:31am
A friend involved in a cycle v cycle accident on a cycle path was in the words of the attending paramedics was saved by wearing a good quality cycle helmet.
Eh?... How the hell can you be in a collision with another cyclist on a cycle path? Both are relative slow moving narrow objects, with complete 180 degree vision and nothing to block any potential sounds which may give a warning of other approaching path users...
..as someone who sometimes doesn't wear a helmet, tje issue isn't the assumption of the paramedic which is unfounded at best, but that the collision actually took place, and that it has been compounded by calling it 'an accident' - as if it was somehow unexpected or not caused by a failing by one or both parties.
I wasn’t there to witness it, but one cycle rode into the back of the other, my friend was knocked off her bicycle and hit her head on something that cracked the shell of her helmet. I think a paramedic probably has more experience and knowledge of accidents and better qualified to assess the likely outcome of an accident with or without the helmet. The number of persons or cause is irrelevant to the use of the word accident. Someone was hurt, it wasn’t deliberate so which verb would you prefer ?
Two wheels preferred.
cycle tramp
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Re: Advice on Helmets, again (was price vs quality)

Post by cycle tramp »

ymfb wrote: 19 Sep 2023, 10:52pm
I wasn’t there to witness it, but one cycle rode into the back of the other, my friend was knocked off her bicycle and hit her head on something that cracked the shell of her helmet. I think a paramedic probably has more experience and knowledge of accidents and better qualified to assess the likely outcome of an accident with or without the helmet. The number of persons or cause is irrelevant to the use of the word accident. Someone was hurt, it wasn’t deliberate so which verb would you prefer ?
Collision- whilst it wasn't a deliberate act the standard of cycle craft shown by the person who ran into your friend fell below an acceptable standard, either through lack of attention or care. As one would expect when driving or motorcycling - a safe braking space should be kept between each cycle...
It's time to go :-)
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