Nice article in the NY Times about helmets

DaveMcC

txom wrote:

But the article doesn't mention this and says "the obvious conclusion to draw from a sustained divergence in the injury ratio without a change in helmet wearing rates is precisely that helmets aren’t responsible for the change in ratio – it’s actually down to something other than the wearing of a helmet."

It seems to me that the sustained divergence is caused by the increase in the amount of cycling in combination with the wearing of helmets.

Just to be clear - the meaning of 'divergence' is that if you had an identical crash in 1990 and in 2010, you'd be less likely to get a head injury now than you would then - the relative injury rates are moving apart (diverging).

It's not easy to attribute this to a larger number of cyclists (with the same helmet wearing rate - in fact it's probably falling, which makes it even harder to believe, but let's pretend it's the same). You come off and the number of other cyclists is making your helmet *more* effective?

On the other hand, it's easy to imagine that people are having slightly less serious crashes now than they did two decades ago. Say a tiny shift has happened (like bike lanes) which makes people a tiny bit more likely to have a solo fall than be pasted by a car. That means on average people who get taken to A&E after a crash have less serious injuries all round - still scraped up their arm, but not had their head smashed off a bonnet.

The absolute number of cyclists is not particularly relevant - the number of people cycling has increased, but if they didn't have a helmet law, it could have increased much more (the best indicator of this is that Aussie bike hire schemes are running under 10% of capacity compared to those everywhere else in the world, even though their conditions for riding are, on the face of it, probably better - flat and great climate).

The bottom line is that the government paid for a previous study (which was discredited) and they've paid for the same people to do another. Are we really surprised they're presenting data that they claim supports the government's line? That's like basing the decision on Scots independence on a poll arranged by the SNP - what do you think the answer would be? (On the other hand, bet you a poll by Westminster would be quite the opposite!)

At the end of the day, I don't have the time or inclination to try to persuade anyone to change religion. The point of the article was really just to make sure that people on the one side didn't start quoting second-hand government spin as though it was the kind of breakthrough that the authors of the study are spinning in the media.

Your mind (and mine ) is already long made up.

meanredspider

DaveMcC wrote:

Say a tiny shift has happened (like helmet design has improved in 20 years)

FTFY

DaveMcC

Yeah, that's also a possibility. Because the researchers included everything from 'grazed chin' and 'split lip' to 'crushed like a ripe watermelon' under their definition of 'head injury', even something like helmets covering slightly more of your head these days would be portrayed as an improvement in their ratio. (You could even have a significant increase in helmet-wearing deaths as long as it was balanced out by a bigger fall in grazes.)

Personally I doubt helmets have become significantly better over the years. In order to fit the data, helmets would have had to improve steadily in terms of their effectiveness against overwhelmingly minor injuries like bruises, for two decades straight. This despite there being no commercial pressure to make them more effective, but intense pressure to make them as light and well ventilated as possible - right down to the limits of the standard.

And yeah, back in the day you'd buy a Snell B95 helmet, but now they're almost all certified to the "particularly weak" EN 1078 (that comment doesn't strictly apply to AUS, obviously, but since the manufacturers are largely the same...)

I think it would be pretty revealing to look at hospital admissions policies - cyclists are mostly brought in for observation just in case, then released without treatment, which is why 'head injury' is the cycling injury type with the quickest discharge rate from hospitals. If guidelines started bringing more people in (who don't turn out to be injured beyond the superficial), that could easily distort the figures.

Of course, the government isn't paying anyone to look into whether admissions policies are flattering the effects of MHL...

txom

OK, I can see I misunderstood the divergence.

Fewer collisions of the type that cause head injuries seems plausible, and as you say hospital admissions policies may have changed.

Is it possible that helmet wearing actually increased in NSW over the period? After all, it appears to have done in the UK (http://www.cycle-helmets.com/england_helmets.html), although we didn't have the spike caused by a helmet law.
I admit that the decision to not release data on helmet usage in NSW does seem suspect, but that doesn't necessarily mean that usage decreased.

By the way, my mind wasn't made up a long time ago, I'm just trying to get my head around the "research" and the arguments.

bompington

txom wrote:

By the way, my mind wasn't made up a long time ago

What on earth are you doing on an internet discussion forum? ;-)

meanredspider

Hmmm - I'm not sure about your view on very minor injuries. People tend not to bother going to hospital for very minor injuries like a bruise or minor graze - it's far too much bother. I'd also dispute your view on helmet design - in my experience over the last 20 years, materials and moulding technology has moved on leaps and bounds including, in particular, comoulding capability not to mention FEA techniques etc. I absolutely accept it's not clear from the study but I don't think your argument on minor injuries holds water particularly well.

DaveMcC

meanredspider wrote:

Hmmm - I'm not sure about your view on very minor injuries. People tend not to bother going to hospital for very minor injuries like a bruise or minor graze - it's far too much bother. I'd also dispute your view on helmet design - in my experience over the last 20 years, materials and moulding technology has moved on leaps and bounds including, in particular, comoulding capability not to mention FEA techniques etc. I absolutely accept it's not clear from the study but I don't think your argument on minor injuries holds water particularly well.

Of course, for minor injuries people don't tend to go to A&E at all - whether it's a grazed elbow or a split lip.

When they do end up in A&E all their injuries will be coded, say, broken elbow, grazed back and arse, bruised/grazed face, and so on. All minor injuries by body part were included in the study (they did at least have the good grace to list the codes).

One thing I wonder about is whether the use of helmets - i.e. the widespread appearance of cracked helmets- promotes A&E visits (because people think "holy cow batman, my helmet's broken, I'd better get myself checked out") and/or whether admissions of cyclists who attend with a broken helmet are higher than for cyclists who attend with a scalp wound.

How many anecdotes are there of people who take a minor fall, their helmet splits, and everyone from the dog they hit, the cyclists they were with, the ambulance driver and the doctors and nurses tell them they'd be dead for certain without it? I didn't start on page 1 but I bet there are plenty in this topic alone. Is there pressure on the admissions procedure because "we've got a cyclist here who came off so hard his helmet's damaged - we need to keep him under observation"?

I don't know - you can speculate so much either way, which is why the study's pretty useless. The fact that it was paid for by the state (who are trying to defend a law that's coming under pressure) and performed by people whose last paper was discredited... guides me to my hunch that it's not all that it claims to be

Hoopdriver

I just love all this abstruse reasoning and convoluted logic.

The study was actually a pretty comprehensive one, and quite rigorous and well thought-out. It's failing seems to be that it arrived at conclusions that a number of people evidently find awkward and not to their liking, and so we have all this endless, absurdist rationalization. Had it arrived at a different conclusion - that helmets made no difference, or even were a liability - these same critics on this forum would be lauding the study and the scientists behind it as beacons of common sense and intellectual rigor.

It sounds to me more like shooting the messenger.

bompington

DaveMcC wrote:

The fact that it was paid for by the state (who are trying to defend a law that's coming under pressure) and performed by people whose last paper was discredited... guides me to my hunch that it's not all that it claims to be

Yep, nothing like subjecting a study to some rigorous scientific analysis...

CiB

There are much better things to do than waste hours on the net arguing about helmets, hence my absence from this one.

But... I'd hate to see helmets made mandatory, and this sort of report that may or may not be factually correct or statistically sound or supporting a pre-defined position by its sponsors or whatever else may affect its probity, is the sort of thing that slips into the mainstream conciousness and the next time some unknown backbench MP wants to make a name for himself by introducing a private members bill mandating helmet wearing he has this as further ammo in his case.

I'd hope that people argue strongly against these sort of studies precisely because unfounded or unsatisfactory statistics being used to promote bad laws isn't in anyone's interest, not because they genuinely believe that falling off a bike without a helmet can never be worse than doing it with.

Carry on.

bompington

I don't think a lot of people on this forum are in favour of mandatory helmets, I don't think this study, whether flawed or not, is going to change that.
What is significant, I think, is that the received wisdom is that compulsory helmeting is a totally bad thing and counter-productive in terms of reducing injuries. This study certainly suggests that this may not be the case.

As I've said many times before, I personally am still waiting for someone to do proper crash test dummy research, so that at least we can isolate the question "in any given accident, would you be better off with or without a helmet?"

The history of this debate suggests that the issue is complex enough that there will always be wriggle room for people to choose to interpret all evidence according to their own prejudices.

meanredspider

Yup - I'm pretty cynical about all studies in this area but this one does at least seem to be one of the better ones as it involves just cyclists (no pedestrians or car drivers) and uses a like-for-like measure (arm injuries vs head injuries) which would close much of the reporting anomalies that other studies haven't managed to exclude. It also has some clear markers such as the improvement to cycling infrastructure that shows that the measures are sensitive to changes that we can (probably) all agree improve cycling safety (better cycling infrastructure) with the the results we'd all expect.

It's far from perfect - I don't believe that any cycling stats on helmet effectiveness will ever be perfect as it's very difficult to measure - but i do think it's one of the better studies.

As for the question of who funded it: this is true of any study. Somebody needs to fund it and rarely is that body truly agnostic. It comes with the territory.

Almost nobody wants mandated helmet wearing

UndercoverElephant

Anyone posted this one yet?

http://www.bikeradar.com/news/article/n ... ury-35498/

*Runs and hides, wearing a helmet in case I trip*

meanredspider

UndercoverElephant wrote:

Anyone posted this one yet?

http://www.bikeradar.com/news/article/n ... ury-35498/

*Runs and hides, wearing a helmet in case I trip*

It's a very poor article stating something that is pretty obvious: of course helmets protect your head/brain - I think it's a minority that believe they don't (even TV packaging protects the TV). The "anti" argument is largely whether the risks are high enough to warrant the wearing of helmets and whether helmet wearing introduces new risks.

DaveMcC

bompington wrote:

What is significant, I think, is that the received wisdom is that compulsory helmeting is a totally bad thing and counter-productive in terms of reducing injuries. This study certainly suggests that this may not be the case.

Well, the study doesn't look at the number of injuries controlled by exposure at all (by design), so it doesn't refute fears of a counter-productive affect (although it certainly allows people to claim so, probably by design!)

An example of the actual injury counts in Australia looks like this, I think you'll agree not such a glowing endorsement:

bompington wrote:

As I've said many times before, I personally am still waiting for someone to do proper crash test dummy research, so that at least we can isolate the question "in any given accident, would you be better off with or without a helmet?"

Although perhaps nobody's done crash test dummies in the way you'd like, there is loads of evidence that you're mostly better off having a helmet between you and the ground (unsurprisingly - rotational injury is perhaps the exception).

Even if someone built a helmet that was 100% effective against injuries it wouldn't change opposition to them because the argument against helmets has never been that they don't work (in the sense of 'work' your question implies).