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Don’t blame mandatory helmets for cyclist deaths in New Zealand

An article published in the current edition of the New Zealand Medical Journal calls for the repeal of mandatory helmet laws (MHL) for cyclists because it claims the law caused 53 premature deaths per…

A recent NZ study which claimed helmet laws caused 53 deaths a year is flawed. Danielle Scott

An article published in the current edition of the New Zealand Medical Journal calls for the repeal of mandatory helmet laws (MHL) for cyclists because it claims the law caused 53 premature deaths per year and halved the number of commuter cyclists.

Study author Colin Clarke says he set out to assess New Zealand’s mandatory helmet laws and came to his conclusion by pooling injury and behavioural data from various sources.

But correlation does not imply causation – and this is one reason Clarke’s analysis falls down.

Randomised controlled trials (RCT) are the gold standard when trying to establish a causal link between factor A and outcome B. However, not every potential causal link can be studied this way.

In Clarke’s analysis, enacting a mandatory helmet law is factor A and negative events such as premature deaths constitute outcome B. But his paper fails to meet any of the necessary criteria to establish a causal relationship. This generally requires at least four stages of analysis:

1) strength of relationship
2) correct temporal ordering
3) presence of dose response
4) elimination of potential confounders.

Let’s see how Clarke’s analysis shapes up against this criteria.

1) Strength of relationship

The first step in establishing a causal link is to measure the association between factor A (helmet laws) and outcome B (cyclist injury or death).

For a trend analysis such as this one, it is important to estimate and compare the changing rates of injury among one or more cyclist groups. Then, when introducing an intervention such as mandatory helmet laws, you need to effectively estimate the injury rate before and after the intervention, to assess whether it had an impact on the outcome, or whether it is part of a larger trend.

Clark fails to mention that rates of commuter cycling were declining from around 1986, long before mandatory helmet laws were introduced in 1994. And long before helmet use began to increase, from 1990.

The Prudent Cyclist

2) Correct temporal ordering

For factor A (helmet laws) to have caused outcome B (cyclist injury and death), A must precede B in time.

Clarke does compare data from before and after the helmet laws were introduced. But the data is from 1988 to 1991 (three years before the helmet laws) and 2003 to 2007 (13 years later). Clarke presents no data from around the time the laws were introduced, with the exception of fatalities.

This is an important distinction because adjacent dates are more correlated than dates further apart. On the flip side, fatalities, injuries and cycling rates nearer in time to the introduction of mandatory helmet laws are more likely to be influenced by this change.

Clarke links a 51% reduction in average hours cycled per person by comparing years 1989 to 1990 with 2006 to 2009. Again, neither period is near the introduction of mandatory helmet laws.

The article does present data for 1996 to 1999, a period more relevant to mandatory helmet laws. When this period is compared with the equivalent pre-helmet law period of 1988 to 1991, there are substantial drops in cyclist injuries overall (down 47%) and serious injuries (down 53%).

This drop remains present even when adjusting for the amount of cycling in those years (down 17% and 53% respectively). The drop in serious cycling injuries (adjusted for million hours spent travelling) when comparing these two periods is significantly more than that for pedestrians, suggesting that mandatory helmet laws protected cyclists, rather than put them at risk.

Additionally, there was a 23% decline in bicycle-related fatalities in the immediate three years after the helmet laws were introduced (1994 to 1996) compared with the preceding three years (1991 to 1993). Clarke does not mention this fact in his analysis and discussion.

3) Presence of a dose response

In a causal relationship, increases or decreases in a factor leads to an increase or decrease in an outcome. This is known as a dose response.

Helmet laws were introduced to increase helmet wearing and mitigate bicycle-related head injuries. In this analysis, the rate of helmet wearing is the dose. From 1990 to 1998, helmet wearing increased to about 95% and remained steady after the helmet laws were introduced, with the largest increase among adults.

Cheryl Rich

The fatality and injury data presented in Clarke’s paper shows a decline in cyclist fatalities, cyclist injuries and the ratio of cyclists and pedestrian injuries (per million hours of activity) during this time when helmet wearing increased rapidly. This shows a dose effect for helmet wearing and declining fatalities or injuries.

Since that time, helmet wearing has remained very high in New Zealand and injuries have risen. This shows there is no dose effect. The implication is that other factors have influenced the rate of bicycle-related injuries and fatalities over the last 18 years beyond mandatory helmet laws.

4) Elimination of potential confounders

When the above three criteria have been met, it is then important to rule out other variables besides factor A that could contribute to outcome B.

Clarke makes no attempt to address confounding factors and attributes all declines in cycling rates and increases in cycling fatalities and injuries to the helmet law.

But, if you look to Clarke’s source for bicycle injuries, Sandar Tin Tin’s 2010 study, you see several potential reasons outside of mandatory helmet laws for declines in cycling rates and increases in injuries. These include the lack of a cycling focus in the New Zealand road safety agenda, an increase in kids being driven to school (due to parental concerns of safety) and the pre-helmet-law decline in cycling rates.

Bigger picture

It is important to question long-standing public health policies. But there are too many weaknesses in Clarke’s analysis and choice of data – particularly the four year absence of data around the time helmet laws were introduced – to support his conclusions that mandatory helmet laws halved the number of cyclists and contributed to 53 deaths each year.

Further, there is no indication from Clarke’s study if the rate of head injuries or fatalities increased or decreased after helmet laws were introduced, as the data presented are for all bicycle related injuries and fatalities.

Past research shows a significant decline in traumatic brain injuries between the pre- and post-mandatory helmet periods. But the scientists involved did not rush to declare that the mandatory helmet laws caused the decline. Instead, they delivered a perfectly weighted comment in light of the data and methodological limitations.

In the future, I would hope Mr Clarke follows their lead.

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62 Comments sorted by

  1. Stefan Muetzel

    Scientist

    havent got any mail
    something is wrong in your system

    regards

    stefan

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  2. Stefan Muetzel

    Scientist

    Yes one can criticise the methods applied in the paper of clarke, but basically both papers come to the same concluison. The main difference I see is that clarke compares the injury rates to the rates of pedestrians, another vulnurable group in traffic to adjust for increases in traffic. This is not entirely correct levels one of the factors influencing the injury rates.

    As for your analysis of the dose response. This is only observed for serious injuries, neither all injuries nor deaths show…

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  3. Colin Clarke

    logged in via email @vood.freeserve.co.uk

    Evaluation of New Zealand’s bicycle helmet law
    See http://www.cycle-helmets.com/nz-clarke-2012.pdf

    The following pdf shows travel to work census details from 1976 to 2006
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2754975/pdf/1479-5868-6-64.pdf

    Fig 1 shows the cycling share
    1976 – 3.4%
    1981 – 5.46%
    1986 – 5.59%
    1991 – 5.39%
    helmet law 1994
    1996 – 4.04% ( 75% of 5.39 )
    2001 – 3.12% ( 58% of 5.39 )
    2006 – 2.52% ( 47% of 5.39 )

    http://www.cyclehelmets.org/papers/p787.pdf
    page…

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    1. Paul Richards

      logged in via LinkedIn

      In reply to Colin Clarke

      Colin you are right on track and the centre of gravity on this issue is turning slowly. Great comments. My perspective is the humanising of cities is the path both countries could have gone down rather than compulsory helmet legislation. The legislation was just a token effort. Both countries fell for the motor industry lobbying, however it's not to late to alter our mindset and get behind humanising cities.

      I respect good vehicle infrastructure and understand scapegoating the pedestrian and…

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  4. Chris Gillham

    Journalist

    This is the usual fallback on confounding obfuscation that explains everything except the bleeding obvious. e.g. less cycling not because of helmets but because of an increase in children being driven to school due to parental concerns of safety.

    What on earth do you expect when you legislate helmets under the premise that cycling is so dangerous their kids will probably be dead or in a wheelchair without them? Of course, all that extra car traffic does wonders for the safety of all road users…

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    1. Harvey C

      Cyclist

      In reply to Chris Gillham

      Well spotted Chris. These attempts at obfuscation get a bit tiring.

      I noticed a lack of reply to Dave Kinkead excellent questions.
      “Yet even here, research calling for helmet laws fail to adequately explain why: 
      - the improvement in fatality rates for cyclists has lagged motorists and pedestrians since the introduction of the law in Australia. 
      - helmet law jurisdictions have considerable lower cycling participation levels than non-law jurisdictions 
      - it is many times times safer to cycling…

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  5. Dave Kinkead

    logged in via Twitter

    Jake, - can you show me any research whose conclusions support mandatory helmet laws that pass the four tests you outline above? I didn't think so but please correct me if I'm wrong.

    Causal relations stemming from the impact of legislation is obviously very difficult to measure due to the issues you raise but it still allows for falsifiability of hypotheses - phenomena that should not occur if the theory is plausible.

    Yet even here, research calling for helmet laws fail to adequately explain why:
    - the improvement in fatality rates for cyclists has lagged motorists and pedestrians since the introduction of the law in Australia.
    - helmet law jurisdictions have considerable lower cycling participation levels than non-law jurisdictions
    - it is many times times safer to cycling in OECD helmet law free jurisdictions than Australia or New Zealand.

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    1. Tim Connors

      System Administrator / Public Serf

      In reply to Dennis Alexander

      And if you're wearing a helmet, the odds of getting hit and needing it (unfortunately, when it least likely to protect you, because a cm of polystyrene doesn't really impede 2 tonnes of metal) are increased:

      http://www.scientificamerican.com/article.cfm?id=strange-but-true-helmets-attract-cars-to-cyclists

      See also: risk compensation: http://en.wikipedia.org/wiki/Risk_compensation

      None of us are saying you shouldn't wear a helmet. We're saying you shouldn't be *forced* to wear a helmet when circumstances don't warrant it. The state *forces* us to do something that will cause other people to risk compensate, putting us in more danger! Let the user do their own risk calculations.

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    2. Dennis Alexander

      logged in via LinkedIn

      In reply to Tim Connors

      What????
      So more people who are riding on the road are sensible enough to wear helmets is the actual stat here.

      And if you've ever had to scrape a kid off the road after they've burst off a footpath (cyclepath in ACT) and hit a car and seen the helmet afterwards, you'd probably think twice about the *forced* or are you happier to scrape dead kids off the road. From personal experience, a centimetre of polystyrene and a little thin plastic shell can be the difference between life and death. Or is your *lifestyle* more important than someone else's life.

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    3. Tim Connors

      System Administrator / Public Serf

      In reply to Dennis Alexander

      My lifestyle will not be affected one way or the other if helmets wearing was not mandatory. I will continue to choose to ride with helmets for the majority of my trips (except perhaps to the local shops) because the majority of my trips contain an element of risk (I ride fast for sporting purpose, and commuting on busy direct roads).

      Where my lifestyle (or more correctly, my life expectancy) is affected, it's because helmet legislation is strongly associated, in Australia (maybe not in New Zealand…

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    4. Dave Kinkead

      logged in via Twitter

      In reply to Dennis Alexander

      Dennis

      The problem with arguments like yours - that because something is possibly good, it must be forced on everyone - is that it they apply to many things with much greater force than they do to cycling.

      You, like most people who support helmet laws, seem to forget or ignore the fact that the head injury rates for motorists, pedestrians and cyclists are almost identical. Yet for every poor cyclist whose head 'is scraped off the ground', there are 50 motorists whose heads have to be scraped from the inside of their cars.

      So if you support bike helmet laws 'because they save a few lives', then you must also support car helmet laws because they would save many times more (or hats-in-the-outdoors laws, or alcohol & tobacco bans). Yet, I think it is safe to assume that you don't wear a helmet when driving or walking across the road, which indicates to me that you are applying double standards or not thinking this through.

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    5. Harvey C

      Cyclist

      In reply to Dennis Alexander

      "http://www.infrastructure.gov.au/roads/safety/publications/2006/pdf/death_cyclists_road.pdf
      The odds of survival are better with a helmet."

      I wouldn't be so sure, especially when relying on information from the Australian Transport Safety Bureau (ATSB)..

      In 2000, the ATSB released a meta-analysis, that claims to provide "overwhelming evidence" that bicycle helmets reduce the risk of brain injury.
      http://infrastructure.gov.au/roads/safety/publications/2000/pdf/Bic_Crash_5.pdf
      This claim…

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    6. Paul Richards

      logged in via LinkedIn

      In reply to Dennis Alexander

      Denis - how do we know? There has been no statistics on what happens in a given situation with a "helmet" on in fatal crashes in that 2006 infrastructure PDF.

      How can the statistic quoted have validity if they don't record a baseline of deaths with and without "helmets" on roads.

      We all know if we fall off a cycle, the leverage can cause high impact and helmets can protect us, i.e. road and mountain bike racing, taking risks on the raggedy edge of fatigue and output.

      But how does 1200 kg of steel, iron, rubber, glass, plastic and high explosive equate to 11 - 20 kg of bicycle when hit by a car? Not to mention 40 tonnes of B double.

      Road infrastructure, is the key to road cycling safety. Helmets do nothing to negate the weight and momentum differentiation.

      We are all fools if we actually believe they do. 12kg vs 1200kg come on seriously?

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  6. John Nightingale

    logged in via Facebook

    Three comments that haven't been made as yet:
    1. the argument has been going on for years, ever since compulsion was put on the heads of cyclists. This indicates to me that there's nothing much in it as far as statistics are concerned. It reminds me of the endless controversy about whether the industrial revolution in England raised workers' living standards before 1840: answer: maybe, maybe not, too close to call. So this aspect of the to-and-fro of helmet compulsion will just go on and on and…

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  7. Matt Stevens

    Senior Research Fellow/Statistician/PhD

    Governments would be better off making more bike paths with clear separation of pedestrian and bike lanes. Similarly, with roads, make a bike only lane on the side.

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    1. Dorothy L Robinson

      logged in via email @gmail.com

      In reply to Matt Stevens

      Bike lanes on one side of the road are OK until you come to an intersection.

      John Franklin, author of Cyclecraft, has provided a summary of relevant research at: http://www.cyclecraft.co.uk/digest/research.html

      On roads, motor vehicles are looking out for other vehicles, so it's reasonably safe and convenient for cyclists who have experience of the road conditions and can make intelligent choices about their routes.

      Most collisions happen at intersections - that's where cyclists need to…

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    2. Luke Turner

      logged in via Twitter

      In reply to Dorothy L Robinson

      My view is that it depends on the circumstances. For low-speed residential areas with low traffic volumes, integration with traffic is best.

      But for a high-speed, high-traffic roads I would much rather a segregated bike lane. I have to wonder about this idea that riding on the footpath is so much more dangerous than riding on busy roads. If you were to take your 8 year old son or daughter out on a bike on a busy 4 land road, would you ride on the footpath or in the traffic lane?

      This is Ann St in Brisbane near where I live. 4 lanes of cars, semi-trailers, cement trucks moving at 60km/h (or more):

      http://bit.ly/zEcZ9P

      I can take the lane if I have to, but it's not my idea of fun. So often I'll just ride slowly on the footpath, because it feels much safer, and indeed is much safer.

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    3. Dorothy L Robinson

      logged in via email @gmail.com

      In reply to Luke Turner

      If you are prepared to give way at the intersections, just like a pedestrian, it would be safer to ride slowly on the footpath.

      Most places where segregated cycle-paths are contemplated are areas with lots of traffic lights. In exceptional circumstances cyclists could be required to give way and still be beneficial.

      The problem is the "one size fits all" attitude, leading to funds wasted on facilities that lie unused while cyclists continue to use the roads, which they find safer and more…

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    4. Harvey C

      Cyclist

      In reply to Luke Turner

      Good point Luke. In Sydney, I find riding in back streets safe and easy. There is no problem integrating with the traffic. I don't see much need for a dedicated bicycle lane.

      On main roads, it is a different story. Motorised traffic is much faster, increasing the risk of accidents. Motorists are not as patient with cyclists. I don't feel safe riding in this environment, which is why I sometimes use the footpath if I have to go on a main road. A physically separated (ie. not just paint on the road) bicycle lane would have much more value there.

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    5. Dorothy L Robinson

      logged in via email @gmail.com

      In reply to Paul Richards

      The key is the statement and video at 2:43 "These can only be passed at low speed", meaning that vehicle drivers are forced to slow down. The photo, together with the road markings, indicates that the cycle crossing is on a raised platform.

      Once the problem of excessive speed has been solved (without resorting to squeeze points that can increase the risk of collisions with cyclists), single-lane roundabouts aren't a problem.

      The same applies to cycle lanes on one side of the road. If you…

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    6. Paul Richards

      logged in via LinkedIn

      In reply to Dorothy L Robinson

      Dorothy - on all round abouts we have no choice in law but to give way to everything on it. People often chose not to comply, because it's easier.
      It's not complicated, people choose to break the law for convenience.

      We both agree this is happening, so yes we need compliance - I agree.

      The European layout allow an obvious distinction between traffic, gives a physical segregation, creates driver awareness and a chance to comply that is easier than not complying. We don't need cheap solutions…

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    7. Dorothy L Robinson

      logged in via email @gmail.com

      In reply to Dorothy L Robinson

      Surely one difference, Paul, is the legal liability situation, that Dutch drivers are considered at fault when they injure cyclists unless they can prove otherwise?

      I'm struggling to get my council to spend $50,000 per year (in conjunction with 50:50 RTA funding for new construction) on cycling. Even putting a concrete circle in the road to make a roundabout and re-aligning the pavements costs $150,000 - $250,000.

      Speed pillows have been specifically designed so that they don't affect emergency…

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    8. Paul Richards

      logged in via LinkedIn

      In reply to Dorothy L Robinson

      "...one difference, Paul, is the legal liability situation" - Dorothy

      Yes, but how so? Their system defaults to automatic driver fault if there is contact between a cyclist and motor vehicle. But given we have in every state written in law, that a driver at all times must give way to cyclists and pedestrians, why doesn't it carry weight? In law it carries the same power, we just have to be willing to prove it.

      If you remember the Shane Warne incident recently the cyclist didn't want to…

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    9. Dorothy L Robinson

      logged in via email @gmail.com

      In reply to Paul Richards

      As an elected councillor, trying to get a bicycle strategy in place before the end of my term of office (not sure I want to stand again), I have to approve the budgets, so I know how much Councils actually pay for these things!

      Even with the best will in the world, I can’t get some things implemented retrospectively. The nine non-cycling councillors will accept the advice of the Director of Engineering that removing on-street parking will not gain public acceptance.

      I’m all for humanising…

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    10. Paul Richards

      logged in via LinkedIn

      In reply to Dorothy L Robinson

      Dorothy - disappointed your were a statistic in this war some drivers wage unknowingly on us. That is why segregation of traffic is the key to humanising cites.

      Did you pursue civil action? That is the recourse in law here and where we differ from the Netherlands. You are entitled to pursue damages for trauma, I would suggest you still chase this matter down through legal aid. It can even be done without up front payment to a regular legal firm also, they will pursue a case taking payment only…

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  8. Colin Clarke

    logged in via email @vood.freeserve.co.uk

    ‘Deaths of cyclists due to road crashes’ 2006 report pdf

    The evidence presented may not convey the full picture, for example,
    some non-wearers may typically be a higher risk due to other factors. In NSW between 1996 and 2011, of known fatality cases that had been drinking alcohol, 10 were helmeted and 12 without helmet . Nine of the 12 non-helmeted cyclists had a BAC of 0.150 or above and only 1 of the 10 helmeted had this level. Six of the 10 helmeted were at low levels of between 0.001-0.019…

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  9. Ashley Hooper

    Farm worker

    I'm commenting here just for the sake of subscribing to any future comments on this thread - there doesn't seem to be a way to subscribe to comments otherwise, strangely.

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  10. Luke Mancell

    Equities trader

    Re: the loaded "Prudent Cyclists" picture. We see the conflation of two radically different cycling styles. The cyclist in the foreground is clipped onto a racing posture fixie whereas the unclipped cyclist in the background is on an upright posture hybrid town-bike or, perhaps, going by the chain rings, an unsuspended mountain bike with road tyres. Why are these two cycling modes lumped together? Even Darwin's local government manages to uncouple the two.

    Cycling isn't a monolith. Compulsory…

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  11. Luke Turner

    logged in via Twitter

    Talk about the pot calling the kettle black.

    Last year Jake Oliver co-authored an article (http://bit.ly/ywt02M) on mandatory helmet laws which claimed to find "a positive effect of compulsory cycle helmet legislation on cyclist head injuries...such that repealing the law cannot be justified."

    So did this study meet Mr Oliver's four criteria for establishing a causal relationship between helmet laws and injury rates? No, not even close.

    Oliver and co. actually admitted in their own paper…

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  12. Jake Olivier

    Associate Professor, School of Mathematics and Statistics at UNSW Australia

    Luke Turnier (sic),

    Based on this and other responses, it is clear you have made up your mind about helmet laws. Your position appears to start with the conclusion that helmet laws are bad and then you work backwards to find any evidence to support your conclusion while ignoring any evidence to the contrary. It is clear your mind is made up and you refuse to be confused by the facts. As a result this response is directed at those who have not. Luke, you can stop reading now if you haven’t already…

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    1. John Nightingale

      logged in via Facebook

      In reply to Jake Olivier

      Oh dear, I think you've made up your mind, too, Jake.

      The statistics just aren't good enough to say helmets are good or not much good. I understand that you must have invested a lot of energy in this work, and if it's published in a first class journal you will gain the expected academic preferment. Yep, I've played that game, too.

      But it's 'line ball' in terms of finding what you want in the figures, using them to bolster your view and anti-bolster your opponents' views. This is the nature of argument. In this case it can go on forever because neither cause is clearly on the money.

      Helmet laws have to rely on other than statistics. Thus the wider range of argument being put in this discussion.

      For my money, cycling will only be safer when urban local roads have a 30kph speed limit and cars are strictly liable for all accidents involving pedestrians and cyclists.

      Funny how a cheap and simple pair of measures are impossible in the Lucky Country.

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    2. Dave Kinkead

      logged in via Twitter

      In reply to Jake Olivier

      Jake - doing exactly what you accuse others of in a response to an accusation of hypocrisy is, I would suggest, the very embodiment of both hypocrisy and irony.

      Neither does labeling any and all who disagree with you as anti-helmet zealots indicate that you are open to engage in honest debate about an important issue. Rather, it indicates an inability to even see the distinction between helmets and helmet laws, and how one can support helmets while opposing helmet laws.

      You also claim you…

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    3. Luke Turner

      logged in via Twitter

      In reply to Jake Olivier

      Another typically evasive response from Jake Olivier.

      If you now claim that your paper does establish causality, then why did you explicitly write in the paper that it was not possible to infer causality, and that you had simply "assumed" it? It appears you want an each-way bet on this one.

      The results of your model suggested that the introduction bicycle helmet law also reduced head and arm injuries for PEDESTRIANS. This was the most statistically significant result in your entire study…

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    4. Alan Todd

      logged in via Facebook

      In reply to Jake Olivier

      Jake,
      I always understood that the conversation was a place for civilised debate, hopefully contributing to the advancement of our understanding of the world we live in, and how best to cope with its practical and ethical challenges. You do this cause no service by by name calling against those who disagree with you. Such expressions as “the anti-helmet crowd” and “ the anti-helmet playbook” are unworthy of you. Likewise, to dismiss the helmet law “debate” as a myth is cheap.
      Is it just too…

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    5. Harvey C

      Cyclist

      In reply to Jake Olivier

      Jake states:
      "1. We found a 29% drop in head injuries relative to limb injuries."

      "found" is not the right word. This claimed 29% drop is not an inevitable result of the underlying data. It seems to be the result of the artificial model chosen, that created two disjoint trends before and after the helmet law, with a gap between them. It should be no surprise that the chosen model results in a sudden drop at the time of the helmet law, considering that the model is constructed to have a jump…

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    6. John Harland

      bicycle technician

      In reply to Jake Olivier

      A helmet covers part of the skull. Without doubt it protects that part of the skull from abrasion and laceration. Therefore helmets reduce head injuries, no argument.

      The question is: do helmets reduce incidence of brain injury? The data is much sketchier on that. Indeed the IsolateCyclist editorial cited simply claims that: "Most medical professionals see helmets as the best way to avoid head injuries and perceive them as saving lives".

      "See" and "perceive" and "head injuries".

      Most examples…

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  13. Ashley Hooper

    Farm worker

    Jake, do you have any statistics on serious head injuries per kilometre travelled for cyclists, pedestrians, and all other motor vehicle users not legally obligated to wear helmets?

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  14. Nigel Perry

    Computer Scientist at University of Canterbury

    I'd suggest article is missing one of the elephants in the room - yes I expect there is a hold herd of them when it comes to this topic!

    But first, I'll also do so and make a comment. When talking about does response to say helmet wearing increased in NZ to 95% over 1990-1998 is somewhat misleading. Within that period there was a sudden step when the law was introduced, from a low to a high wearing rate. That's the dose. There was however no corresponding step in the head injury rate of cyclists…

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  15. Michael Tam

    General Practitioner, and Conjoint Senior Lecturer at UNSW Australia

    Dear Jake,

    Thank you for a very readable description of the problems with establishing causality. However, I must agree with some of the criticisms by the other commentators.

    Firstly, it must be recognised that using those criteria, it is impossible to confidently infer causality in either direction for any important outcomes of mandatory helmet laws. This means that recommendations to public health policy at present cannot be simplistically reduced to relying on such data.

    Secondly, is…

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  16. Colin Clarke

    logged in via email @vood.freeserve.co.uk

    Jake

    You stated;
    The helmet law debate, in reality, is a myth.

    The UK report RSRR30 reported 31 papers in favour of helmets or legislation compared with 32 against.
    ref page 72
    Towner E, Dowswell T, Burkes M, Dickenson H, Towner J, Hayes M; Bicycle Helmets – A review of their effectiveness, A critical review of the literature, road safety report No 30; Department for Transport, UK, 2002
    (Towners report failed to fully report about Robinson DL; Head injuries and bicycle helmet laws; Accid…

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  17. John Harland

    bicycle technician

    The onus is on those pressing for mandation (whether its introduction or continuance) to demonstrate sufficient reason to mandate helmets. The default is voluntary usage.

    The data of the article conflicts with that in other articles on the subject. I find it no more convincing than those others.

    There is considerable evidence that helmets would improve outcomes for drivers in collisions, and even more for frontseat passengers. Can you even buy a car helmet readily, let alone have to wear one?

    I have yet to see it but I suspect that we might demonstrate that pedestrians might come out better from misadventure with cars as well. Should pedestrians wear helmets?

    What about Rugby players, or skiers?

    Mandation is the first resort of the fascist. Education and encouragement are the tools of democracy. If helmets are so good, let's educate and encourage people to use them, including in cars.

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  18. John Harland

    bicycle technician

    "Clark fails to mention that rates of commuter cycling were declining from around 1986, long before mandatory helmet laws were introduced in 1994. And long before helmet use began to increase, from 1990."

    The first contention is not borne out in the linked data, as far as I can see. The data does not seem to show a decline from 1986

    Figures on helmet use are likely to be unreliable, judging by Victorian experience. How, and where, was the sampling done?

    Does the study take any account of…

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  19. Adele Pring

    educator

    I'm curious to know whether anyone has compared cyclist safety in Australia with cyclist safety in Japan where it seems millions of people cycle.

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    1. Harvey C

      Cyclist

      In reply to Adele Pring

      I am not aware of any comprehensive study that compare cycling safety in Australia with Japan or other countries. This is rather odd. After taking the “lead” in introducing compulsory helmets, we should be proud to announce the amazing cycling safety we now enjoy in Australia.

      One researcher has compared cycling safety in Australia with several other countries.
      http://acrs.org.au/wp-content/uploads/ACRS-Vol_21-3-WebLR.pdf

      Countries with a helmet law or high helmet usage (Australia, US…

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  20. Simon Batterbury

    Associate Professor at University of Melbourne

    A great deal of interesting discussion. Jake is taking a positivist view. No doubt, given the rather sketchy data, it is possible to say that wearing helmets reduces certain types of injuries. Not sure anybody is denying that, unless you are extremely good at statistics and able to contest the work successfully.

    But the difficulty is that policymakers never had good data when helmet laws were introduced, and largely lack it now. They are not skilled in stats and the data we now have is not exactly…

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    1. Colin Clarke

      logged in via email @vood.freeserve.co.uk

      In reply to Simon Batterbury

      http://www.cyclehelmets.org/papers/p787.pdf BICYCLE HELMETS: A SCIENTIFIC EVALUATION provides useful information for anyone considering the helmet issue in more detail.

      In Victoria, where helmet laws started, the fine for not wearing a helmet has jumped to $146 - which is likely to bring in at least $1 million in revenue for the state government this financial year.

      Read more: http://www.theage.com.au/victoria/rider ... z1p0WpU5v4

      They started off at $15 but now have made life difficult…

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  21. Ashley Hooper

    Farm worker

    Cycle Helmets - A Duty to Wear?
    Publisher: Martin Porter QC
    Publication date: March 2012
    Document file: Cycle_Helmets-A_Duty_to_Wear.pdf

    Abstract:

    Summary of legal status of cycle helmet wearing in the UK, paticularly where contributory negligence is claimed, from "The Cycling Lawyer" Martin Porter.

    Updated document for a talk presented to the Association of Personal Injury Lawyers on 28 February 2012.

    http://www.cycling-embassy.org.uk/document/cycle-helmets-duty-wear

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  22. Ashley Hooper

    Farm worker

    I don't know if anyone already has figures on this, but I think those in favour of mandatory helmet laws must provide statistics on head injuries and helmet-preventable deaths (numbers of cyclists who died but would have lived had they worn a helmet) *per* cyclist kilometre travelled before presenting any kind of argument in favour of helmets.

    Along with this, equivalents for pedestrians and car passengers would show whether this law had any basis for existing.

    In an earlier comment I asked Jake in what I think was a neutral tone if he had any numbers but he gave no response.

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  23. Colin Clarke

    logged in via email @vood.freeserve.co.uk

    Some new information has come to light, one is from Tin Tin 2010 report.
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2989960/
    Figure 3, is lacking information on ‘Other’ lower extremities. The full data provided indicates
    88/91, Overall TBI -11.87, non-TBI – 18.58, total 30.45
    96/99, Overall TBI – 7.29, non-TBI – 25.72, total 33.01
    03/07. Overall TBI – 6.23, non-TBI – 42.63, total 48.86
    These rates were per million hours spent cycling.
    The non –TBI rates increased from 18.58 to 42.63…

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    1. Jake Olivier

      Associate Professor, School of Mathematics and Statistics at UNSW Australia

      In reply to Colin Clarke

      Colin Clarke,

      Our papers were indeed peer-reviewed, unlike your comments and your reports published on an anti-helmet advocacy website.

      http://acrs.org.au/events/acrs-past-conferences/2013-a-safe-system-the-road-safety-discussion/
      http://acrs.org.au/wp-content/uploads/26_Olivier_PR.pdf
      http://acrs.org.au/wp-content/uploads/28_Wang_PR.pdf

      What exactly is misleading about our comments? Some of them are

      1. How can you draw such strong conclusions when you've performed no statistical analyses…

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    2. Colin Clarke

      logged in via email @vood.freeserve.co.uk

      In reply to Jake Olivier

      Jake asks about;
      Peer reviewed -
      Many papers that are peer reviewed carry some errors and non peer reviewed may even have more errors, peer review provides feedback in most cases and could be helpful. I assume PR in the link indicates press release and not peer reviewed?
      It could be better to include ‘Peer Reviewed’ in small print on articles to make it clear.

      Misleading comments about the NZ paper from Wang et al
      http://acrs.org.au/wp-content/uploads/28_Wang_PR.pdf
      http://journal.nzma.org.nz/journal/125-1349/5046

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    3. Jake Olivier

      Associate Professor, School of Mathematics and Statistics at UNSW Australia

      In reply to Colin Clarke

      Colin Clarke,

      Our papers were clearly peer-reviewed. It is not our problem that you did not make any attempt to verify that.

      You have inserted four points which I will address in turn.

      1 and 2. Your paper really had no methods section as you had no statistical analysis. You made piece-meal comparisons accentuating results you liked and ignoring those you didn’t. I suggest you read the above article again as you arbitrarily choose which time periods and type of injury to compare. This has…

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    4. Colin Clarke

      logged in via email @vood.freeserve.co.uk

      In reply to Jake Olivier

      Some papers say ‘peer reviewed’ on them, yours did not, but we have covered this and it is now clear, thanks.
      .
      The main points I made about Wang et al misleading presentation,
      The 17 year comparison indicated that it lacked credibility when data presented for 8 years showed a 40% reduction for cycling compared to a 2% increase for walking. This indicated that cycling was discouraged to a significant degree.

      The statement
      ‘He claimed that this significant drop was completely attributable…

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    5. Jake Olivier

      Associate Professor, School of Mathematics and Statistics at UNSW Australia

      In reply to Colin Clarke

      Colin Clarke:

      You state “Some papers say ‘peer reviewed’ on them, yours did not, but we have covered this and it is now clear, thanks.” None of the papers say peer-reviewed on them, yet this website lists which ones were peer-reviewed and which ones weren’t. I don’t understand the confusion.

      http://acrs.org.au/events/acrs-past-conferences/2013-a-safe-system-the-road-safety-discussion/

      You take issue with our statement “He claimed that this significant drop was completely attributable to…

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    6. Colin Clarke

      logged in via email @vood.freeserve.co.uk

      In reply to Jake Olivier

      Jake asks about a number of points, shown in (..).
      (Peer review) – I think we have discussed this sufficiently.

      (You take issue with our statement “He claimed that this significant drop was completely attributable to helmet law.” Your paper does not discuss any external causes behind changes in injury rates besides helmet legislation.)
      I had stated
      ‘helmet law discouraged cycling to a significant extent’
      Injury rates are different to cycling levels, so I am a bit confused why linking the…

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  24. Paul Richards

    integral operating system

    Both New Zealand and Australian culture mirror the US allowing motor vehicles to dominate.

    A recent article in "The Economist" magazine highlights the Strict Liability principle* and how valuable it would be to US culture. The parallels for driver culture are self evident.

    Still that is dependant on a personal value set, employer or business partner and how closely this position suits. In other words personal life conditions creating biases. November 20 2013
    _________________________________
    * http://www.economist.com/blogs/democracyinamerica/2013/11/cycling-v-cars

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    1. Paul Richards

      integral operating system

      In reply to Jake Olivier

      Appreciate the perspective in comment.

      "Curiously" wrote Jake Olivier. Why the need to project a parallel between the velocity, weight, terminal inertia of motorbike rider and a cyclist? This has successfully made values carried even more transparent.

      In our cities driver culture is so unbalanced that it has selected the most aggressive, individuals to brave the motor vehicle domination as a percentage of all pedestrians, cyclists and motor cyclist. However, this is 'not what came first' dilemma…

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