Advocacy & Safety - Helmets Reduce Risk of Head Injuries in Skiers by 35%

Last year I posted an article discussing the death of Natasha Richardson and how the newspapers were stating that a helmet could have saved her life. Guess what? A new study Canadian Medical Journal states that ski helmets can reduce head injuries by 35%!!! Maybe we should be using ski helmets instead. They do look more protective.


http://news.yahoo.com/s/nm/20100201/lf_nm_life/us_helmets_safety;_ylt=AmGVnn8077XcuAAsDQ7oLj2s0NUE;_ylu=X3oDMTNsa2Iya2owBGFzc2V0A25tLzIwMTAwMjAxL3V zX2hlbG1ldHNfc2FmZXR5BGNjb2RlA21vc3Rwb3B1bGFyBGNwb3MDOQRwb3MDNgRwdANob21lX2Nva2UEc2VjA3luX2hlYWRsaW5 lX2xpc3QEc2xrA2hlbG1ldHNjdXRyaQ--

http://www.cmaj.ca/cgi/search?andorexactfulltext=and&resourcetype=1&disp_type=&sortspec=date&fulltext=helmet

I wouldn't mind using one this winter.

I ride with one of these, skate helmet I guess.

http://www.amazon.com/gp/product/B002LT2VYQ/ref=ox_ya_oh_product

http://www.cmaj.ca/cgi/search?andorexactfulltext=and&resourcetype=1&disp_type=&sortspec=date&fulltext=helmet

If you look at figure 2 in the study, you'll see that quite a few of the original odds ratios, with their 95% confidence intervals, are disjoint. The original studies are not in agreement, so this study author throws them together in a hopper to make one big average.

The other interesting tidbit is in table 3. It shows that one of the studies indicates that for people over 25, helmets INCREASE risk!

Speedo

This would be so relevant to wearing helmets while cycling if the skiers they studied did all their skiing on public roads surrounded by motorized traffic.

The other interesting tidbit is in table 3. It shows that one of the studies indicates that for people over 25, helmets INCREASE risk!
So what?

1 out of 27 studies showed an increased risk (3.7%). 26 out of 27 (96.3%) showed a decrease in risk.

Last year I posted an article discussing the death of Natasha Richardson and how the newspapers were stating that a helmet could have saved her life. Guess what? A new study Canadian Medical Journal states that ski helmets can reduce head injuries by 35%!!! Maybe we should be using ski helmets instead. They do look more protective.


http://news.yahoo.com/s/nm/20100201/lf_nm_life/us_helmets_safety;_ylt=AmGVnn8077XcuAAsDQ7oLj2s0NUE;_ylu=X3oDMTNsa2Iya2owBGFzc2V0A25tLzIwMTAwMjAxL3V zX2hlbG1ldHNfc2FmZXR5BGNjb2RlA21vc3Rwb3B1bGFyBGNwb3MDOQRwb3MDNgRwdANob21lX2Nva2UEc2VjA3luX2hlYWRsaW5 lX2xpc3QEc2xrA2hlbG1ldHNjdXRyaQ--

http://www.cmaj.ca/cgi/search?andorexactfulltext=and&resourcetype=1&disp_type=&sortspec=date&fulltext=helmet

I remember. It's here. (http://www.bikeforums.net/showthread.php?521735-Natasha-Richardson-Helmets&highlight=Natasha+Richardson)

I looked back because there was some interesting information to be found and there seems to be some similarities to the bicycle helmet debate. There also seems to be a better method of obtaining standardized information about injuries in the ski industry.

According to The National Ski Area Association, 45 deaths occurred out of the 56.9 million skier/snowboarder days reported for last season.

43% of all skiers/snowboaders wore helmets but over 50% of those deaths happened to those skiers/snowboarders who were wearing helmets.

I found a good site on the topic

http://www.ski-injury.com/

There's a section on head injury

http://www.ski-injury.com/specific-injuries/head

and another for helmets in snow sports

http://www.ski-injury.com/prevention/helmet


It’s been a hot topic in the snow-sports safety forum for best part of ten years now – the issue of helmets. High velocity collisions with trees lead to the deaths of Sonny Bono and Michael Kennedy in 1998 and raised the profile of head injuries on the slopes in the media...Most recently, the debate was reignited after the tragic death of actress Natasha Richardson (Liam Neeson's wife) whilst skiing in Canada.

To add fuel to the initial fire, the US Government got on the bandwagon and commissioned the controversial CPSC study which in January 1999 concluded that more than 7,000 head injuries on the slopes each year in the USA could be prevented or reduced in severity by the use of a helmet.

Whilst this publication has been widely quoted in many subsequent publications and on the surface seems to make a conclusive case, this study has been criticised by most leading ski injury researchers (including Bob Johnson & Rick Greenwald) as being politically motivated.

To cut a long story short, the current evidence strongly suggests that helmets may prevent or reduce the severity of many minor/moderate head injuries but there is no data to support the idea that they will protect against fatal head injuries - the forces involved in these sort of accidents are simply too great...

... the real issue is that of risk calculation - i.e. how likely is a head injury to occur? It would appear to be actually very low.

43% of all skiers/snowboaders wore helmets but over 50% of those deaths happened to those skiers/snowboarders who were wearing helmets.

That's a common finding in helmet safety studies. It was used as an argument against hockey helmets in the 1980's. The reason is that people who are wearing helmets often think the helmets provide more protection than they do, and are more reckless. In the case of hockey, this means they're more willing to go charging toward the boards, or deliver a hit at higher speed. In the case of cycling and skiing, it likely applies two ways, it makes people feel invulnerable, and people that use helmets in those sports are likely traveling at higher speed or are more intense participants.

There are very few people that crash badly while riding a beach cruiser to the ice cream store, and those same people are less likely to even own a helmet.

But that doesn't say that helmets don't provide additional protection.

That's a common finding in helmet safety studies. It was used as an argument against hockey helmets in the 1980's. The reason is that people who are wearing helmets often think the helmets provide more protection than they do, and are more reckless. In the case of hockey, this means they're more willing to go charging toward the boards, or deliver a hit at higher speed. In the case of cycling and skiing, it likely applies two ways, it makes people feel invulnerable, and people that use helmets in those sports are likely traveling at higher speed or are more intense participants.

There are very few people that crash badly while riding a beach cruiser to the ice cream store, and those same people are less likely to even own a helmet.

But that doesn't say that helmets don't provide additional protection.

I don't think any one's saying helmets don't provide the protection they were made to provide, but there's a couple of questions you do raise.

Are the types of collisions we fear within the range of protection the helmet provides and do people take greater risks that lead to collisions because they are wearing a helmet (thinking that the helmet will protect them from the consequences of their behavior)?

Are the types of collisions we fear within the range of protection the helmet provides and do people take greater risks that lead to collisions because they are wearing a helmet (thinking that the helmet will protect them from the consequences of their behavior)?

People tend to take bigger risks with more padding around them. But that's talking about a sample population, not an individual. A helmet protects an individual person better than no helmet. The individual's choice to act more recklessly with a helmet on is a separate issue, but cannot be separated statistically.

But a lot of times, the behavior isn't a choice, per se. In any race, a helmet is required. So any head injury occurring during a race counts as an injury while wearing a helmet. People that spend more time on the road are more likely to fall, get hit, or hurt their head while on a bike, but generally, people in that category are also more likely to be wearing a helmet.

People tend to take bigger risks with more padding around them. But that's talking about a sample population, not an individual.

Yet a sample population is a collection of individuals. Interesting.


A helmet protects an individual person better than no helmet. The individual's choice to act more recklessly with a helmet on is a separate issue, but cannot be separated statistically.

could this be why head injuries have risen with helmet use?


People that spend more time on the road are more likely to fall, get hit, or hurt their head while on a bike, but generally, people in that category are also more likely to be wearing a helmet.

Really? How do you figure that?

People tend to take bigger risks with more padding around them.
It isn't clear that "risk compensation" is occuring for road cyclists wearing helmets. "Ninja salmons", for example, don't typically wear helmets.


could this be why head injuries have risen with helmet use?
This would seem as suspicious a result as helmets reducing head injuries is.

It isn't clear that "risk compensation" is occuring for road cyclists wearing helmets. "Ninja salmons", for example, don't typically wear helmets...

true, but it is clear that, head injuries are rising in spite of the increased use of bike helmets (http://bicycleuniverse.info/eqp/helmets-nyt.html).

Something else seems to be in play. Perhaps it's all the attention placed on helmets at the expense of safe riding skills (http://bicyclesafe.com/helmets.html)?

If you look at figure 2 in the study, you'll see that quite a few of the original odds ratios, with their 95% confidence intervals, are disjoint. The original studies are not in agreement, so this study author throws them together in a hopper to make one big average.

The other interesting tidbit is in table 3. It shows that one of the studies indicates that for people over 25, helmets INCREASE risk!

Speedo

Also the interpretation of odds ratios is a bit tricky. It's true that the authors of this study had no choice but to use them as the individual studies were case-control, but still I wonder what most people think an odds ration of 0.65 means.... :)

true, but it is clear that, head injuries are rising in spite of the increased use of bike helmets (http://bicycleuniverse.info/eqp/helmets-nyt.html).

Something else seems to be in play. Perhaps it's all the attention placed on helmets at the expense of safe riding skills (http://bicyclesafe.com/helmets.html)?

Mountain biking has also grown in popularity since 1991, as has BMX, trick fixed-gear riding, and a whole slew of other riskier forms of cycling. I take a spill fairly often on my mountain bike. I've never fallen on my road bike, and use my road bike 10 times the mileage.

I agree that more attention should be placed on safe riding skills...and safe riding practices, such as not taking a ski lift to the top of a mountain in the Cascades so you can ride down. Aside from making you a lazy a**, it also gives you no friggin' respect for the mountain, but I digress.

It isn't clear that "risk compensation" is occuring for road cyclists wearing helmets. "Ninja salmons", for example, don't typically wear helmets.


This would seem as suspicious a result as helmets reducing head injuries is.

It wasn't clear for hockey helmets either. There's no way to quantify the risk people take. But on an accident by accident basis, helmets offer additional protection.

EDIT: Are these studies discussing only injuries by committed road cyclists, or injuries to people on bicycles in general?

So what?

1 out of 27 studies showed an increased risk (3.7%). 26 out of 27 (96.3%) showed a decrease in risk.

Of the 2 studies that broke out an over 25 group one found an increased risk, and one found a decreased risk. So it's really more like 50-50.

The authors of the meta-data study down-selected to the set of particular studies included, so they made a conscious decision to keep the study that concludes increased risk for the over 25 group because they felt that it was significant. That's what.

Speedo

Of the 2 studies that broke out an over 25 group one found an increased risk, and one found a decreased risk. So it's really more like 50-50.

The authors of the meta-data study down-selected to the set of particular studies included, so they made a conscious decision to keep the study that concludes increased risk for the over 25 group because they felt that it was significant. That's what.

Speedo

not an uncommon occurrence in studies that want to show a particular result or when the media wants to grab attention, they can pick out what's attention grabbing, but what is not particularly relevant to what has been learned

It wasn't clear for hockey helmets either. There's no way to quantify the risk people take. But on an accident by accident basis, helmets offer additional protection.

EDIT: Are these studies discussing only injuries by committed road cyclists, or injuries to people on bicycles in general?

All cyclists.

and if wearing a helmet leads to behavior that leads to an injury that is beyond the helmets ability to protect, is the cyclist better off putting it on?

Maybe we should be using ski helmets instead.


I do use mine in the winter. It's warm and comfy.

People that spend more time on the road are more likely to fall, get hit, or hurt their head while on a bike, but generally, people in that category are also more likely to be wearing a helmet.

I gotta disagree here. I won't use myself as a rebuttal example, I'll use the millions of cyclists worldwide who ride every day without a helmet....in places where traffic is much more "unordered" than in the US to boot.

I also recall a study that seemed to indicate that more experience riding tended to decrease one's risk of accidents per hour of riding...maybe CB can cite that one.

.... I also recall a study that seemed to indicate that more experience riding tended to decrease one's risk of accidents per hour of riding...maybe CB can cite that one.

I recall that too, and it seemed to jive with common sense. More skill, more experience, less accidents.

As for the actual study, I'm sure I have it somewhere. I'm at work right now and don't have access to the stuff I keep at home. I'll look for it later.

...but since I am at work, I do have access to newspapers from everywhere and I picked up a Calgary Herald that covers the story.

It's a good example of how the media can show a reduction in minor injuries, can be interpreted in a different way to give an impression that ski helmets prevent major injuries.

a new study by University of Calgary scientists proves people who wear them are much less likely to suffer head injuries in a fall...

Andrew Sawatsky, 29, of Calgary said he always wears a helmet when he skis.

"I've had concussions in the past," ...

The U of C paper suggests traumatic brain injury is the leading cause of death and serious injury among skiers and snowboarders...
(http://www.calgaryherald.com/health/helmets+reduce+head+injury+risk+study/2509014/story.html)

It's only towards the end of the peice that a bit of sobriety enters the scene:

"We recommend wearing helmets for skiing or riding," said Doug Firby, spokesman for Sunshine Village Ski Resort. "We also encourage skiers and snowboarders to educate themselves of both the benefits and the limitations of helmet usage." (http://www.calgaryherald.com/health/helmets+reduce+head+injury+risk+study/2509014/story.html)

If people would educate themselves about ski helmets they could see they protect skiers from minor injuries and not concussions, traumatic brain injuries, and death.

If you just read the article without giving it much thought, it'd be very hard not to think that ski helmets prevent concussions, traumatic brain injuries, and death. If the article was a bit more up front and said that it is only minor injuries that could be reduced by wearing a helmet, would it make the same impact or even be worth writing about? I don't think so. people are worried about concussions, traumatic brain injuries, and death far more, so that's what they write about.

I gotta disagree here. I won't use myself as a rebuttal example, I'll use the millions of cyclists worldwide who ride every day without a helmet....in places where traffic is much more "unordered" than in the US to boot.

I also recall a study that seemed to indicate that more experience riding tended to decrease one's risk of accidents per hour of riding...maybe CB can cite that one.

I've never seen worldwide data, and it wouldn't make sense to have such a broad sample anyway. What I am saying isn't that experienced cyclists don't wear helmets; there are many that don't, just as many inexperienced cyclists do. But in the U.S. if you added up the total number of miles(hours) biked by each group, it wouldn't be a fair comparison, because the helmet-wearers would account for so many more hours and miles biked per person that they would still have an increased risk of head injury.

Most head injuries on hockey skates happen to people wearing hockey helmets, because the people wearing the helmets spend more time on the ice per person than do people who don't where a helmet on the ice.

I'm going to repeat myself. This type of anti-helmet/anti-safety device argument has been used in every sport and every business I can think of. The debate isn't whether helmets offer additional protection, the debate is whether people want to be bothered with wearing a helmet or what risks are they willing to accept so they don't have to wear a helmet. Anti-helmet proponents find every possible argument to justify it to themselves it isn't worth it, just as smoking addicts use every possible justification to think "smoking isn't that bad."

... The debate isn't whether helmets offer additional protection

to some people that is an important matter of debate. If the protection provided is insufficient to the need, why bother?


... the debate is ... what risks are they willing to accept so they don't have to wear a helmet...

if one feels the risk is not great enough to justify the use of a helmet, why bother?

I saw more coverage in The Globe and Mail on the story

http://www.theglobeandmail.com/life/health/helmets-on-the-slopes-cut-head-injury-risk/article1453246/

where the message is as veiled yet the motivation behind the story is a little more up front.


... research showed that in children under 13, the benefit of wearing a helmet was greater than among adults, but there's nothing magical that happens when you're an adult. You are still at risk of injury...

Obligiatory helmet use is something we would really like to see...

...As the popularity of these sports has risen, so too has the number of traumatic injuries and death.

Only in one small passage does the reader get the hint that ski helmets do not protect against traumatic injury and death:


A helmet provided the greatest protection in lift-related incidents. It provided the least protection in out-of-bounds incidents because those injuries are often catastrophic

Nowhere in any of these articles does it place the chances of receiving these injuries in any kind of context. That different types and ages of skiers receive injuries at different rates. That these types of injuries are extremely rare. It is enough that it has happened, however rarely.

It think it was pointed out in skiinjury.com that a skier has a far greater chance of injury on the way to the slopes than on the slopes

I've never seen worldwide data, and it wouldn't make sense to have such a broad sample anyway. What I am saying isn't that experienced cyclists don't wear helmets; there are many that don't, just as many inexperienced cyclists do. But in the U.S. if you added up the total number of miles(hours) biked by each group, it wouldn't be a fair comparison, because the helmet-wearers would account for so many more hours and miles biked per person that they would still have an increased risk of head injury.

Most head injuries on hockey skates happen to people wearing hockey helmets, because the people wearing the helmets spend more time on the ice per person than do people who don't where a helmet on the ice.

I'm going to repeat myself. This type of anti-helmet/anti-safety device argument has been used in every sport and every business I can think of. The debate isn't whether helmets offer additional protection, the debate is whether people want to be bothered with wearing a helmet or what risks are they willing to accept so they don't have to wear a helmet. Anti-helmet proponents find every possible argument to justify it to themselves it isn't worth it, just as smoking addicts use every possible justification to think "smoking isn't that bad."

I still don't agree, I think you vastly underestimate the number of people who ride helmetless all or part of the time and the hours they spend on a bike...even just in the US. But I doubt there is any data I could use to back up my observation, so we'll just have to agree to disagree here.

But you've given me a second point of disagreement now as well. I don't know of anyone in here who is anti-helmet...as in actively either encourages others not to wear one or gives them crap because they do. I'm certainly not anti-helmet...if you want to wear one by all means do so and I will defend your right to do so as well. All I care about is the same courtesy in return. I've been riding a bike for over 40 years, over 30 of which has been regular commuting, in traffic. I simply do not consider riding a bike within my comfort level to be dangerous enough to warrant a helmet, anymore than I consider wearing a helmet when working on my roof or on a ladder. Indeed, I think my risk is greater on the roof or the ladder. I don't see anything radical or anti-helmet about that, and wonder why my choice is so threatening to people who fear the activity more than I do - to the point where they start spouting Darwin and other stupid attempts at feeling a superior part of a small herd.

Point is, nobody is trying to say that helmets are bad, so I'm wondering why you feel the need to respond as you did to something or someone that does not exist...at least in this thread. Who are these "anti-helmet proponents" of which you speak? ;)

It wasn't clear for hockey helmets either.
I sure hope you aren't equating playing hockey with road cycling!


Of the 2 studies that broke out an over 25 group one found an increased risk, and one found a decreased risk. So it's really more like 50-50.
It's still much less than 50-50. There are many other groups that are similar-enough to the one "over 25" group that show reduced injuries. The other results point to this one result as being odd.


The authors of the meta-data study down-selected to the set of particular studies included, so they made a conscious decision to keep the study that concludes increased risk for the over 25 group because they felt that it was significant. That's what.
Speedo
No, they reported the results of all the studies that met their requirements. They can't dump the results they don't like.

true, but it is clear that, head injuries are rising in spite of the increased use of bike helmets (http://bicycleuniverse.info/eqp/helmets-nyt.html).
This article is as poor as anything that is "pro-helmet". You should be embarrased for using it to support your argument. It has the same standard problem of what counts as a "head injury".


Officials hope that by examining emergency room reports more closely and interviewing crash victims, they can find out if more of the injuries are relatively minor and how many people suffered head injuries while wearing helmets. Some bicycling advocates have questioned the statistics on participation in bicycling, and the commission plans to re-examine those as well.


Promoting bicycle helmets without teaching riders about traffic laws or safe riding practices can encourage a false sense of security, according to several risk experts. Helmets may create a sort of daredevil effect, making cyclists feel so safe that they ride faster and take more chances, said Dr. Mayer Hillman, a senior fellow emeritus at the Policy Studies Institute in London.
They "may" and they "may not". Who knows!

Of course, it's strange that helmets scare people from cycling and make them ride recklessly at the same time!


One parallel, risk experts said, is anti-lock brakes. When they were introduced in the 1980s, they were supposed to reduce accidents, but government and industry studies in the mid-1990s showed that as drivers realized their brakes were more effective, they started driving faster, and some accident rates rose.Really? This is presenting a hypothesis as fact.

Maybe something other than brakes caused the increase in speed. Since it seems that not many people actually know how to use anti-lock brakes properly, the brakes are not "more effective".

http://www.mucda.mb.ca/aboutabs.htm


Something else seems to be in play. Perhaps it's all the attention placed on helmets at the expense of safe riding skills (http://bicyclesafe.com/helmets.html)?
No, because no real attention was ever placed on "safe riding skills".

It should be clear to everybody that any piece of safety equipment is a secondary form of safety.

This article is as poor as anything that is "pro-helmet". You should be embarrased for using it to support your argument...".Of course, it's strange that helmets scare people from cycling and make them ride recklessly at the same time...

It should be clear to everybody that any piece of safety equipment is a secondary form of safety.

well, I probably could have better used the source information rather than the NY Times article relating it.

My point is simply that helmet use hasn't resulted in a corresponding decrease in head injury.

For sure, using a helmet is a secondary step of trying to be safe, and more importantly, it has it's limitations. Limitations that many supporters have a problem admitting to.

"Omg, helmets are such a conspiracy.. they don't work at all!! I'm never wearing one they r like uncool and hot ugh!!!"

How about this:

Cool woman falls down hits her head goes into coma, everybody is sad. Smart man falls down, hits his helmet and has to buy a new one, but still gets to post annoying comments on bikefo - people are non-plussed and still skeptical of helmets.

"Omg, helmets are such a conspiracy.. they don't work at all!! I'm never wearing one they r like uncool and hot ugh!!!"

How about this:

Cool woman falls down hits her head goes into coma, everybody is sad. Smart man falls down, hits his helmet and has to buy a new one, but still gets to post annoying comments on bikefo - people are non-plussed and still skeptical of helmets.

Not really. There's nothing wrong with helmets. They can be useful in their purpose. The problem is when people think they are useful beyond their purpose.

It's more like,

http://www.ski-injury.com/prevention/helmet


... the current evidence strongly suggests that helmets may prevent or reduce the severity of many minor/moderate head injuries but there is no data to support the idea that they will protect against fatal head injuries - the forces involved in these sort of accidents are simply too great...

... the real issue is that of risk calculation - i.e. how likely is a head injury to occur? It would appear to be actually very low.

Not really. There's nothing wrong with helmets. They can be useful in their purpose. The problem is when people think they are useful beyond their purpose.


Sure, and an awd car lets me drive 130 in the snow with 100% control!

Maybe helmets do increase risky behaviour, but that should have come out in the wash with the total # of 35% reduction in head injury. Yeah?

a bit fewer cuts, bumps, and bruises with no fewer traumatic injuries and deaths in a remote possibility, that's all.

I sure hope you aren't equating playing hockey with road cycling!


Hmmm. Let's see. Playing ice hockey I dislocated my left shoulder. Riding a bike I broke my right collarbone.

Just as an aside. I wore a helmet with a face mask during my hockey playing days. I really don't have an opinion about how valuable the helmet part was. The face mask, I think, is pretty important.



It's still much less than 50-50. There are many other groups that are similar-enough to the one "over 25" group that show reduced injuries. The other results point to this one result as being odd.


There are only two that call out the over 25 group. There is a general trend for reduced benefit of the helmet with age.



No, they reported the results of all the studies that met their requirements. They can't dump the results they don't like.

Precisely. This study we are discussing met the minimum requirement of well informed analysts. YOU can't disregard the result simply because you don't like it.

Speedo

Hmmm. Let's see. Playing ice hockey I dislocated my left shoulder. Riding a bike I broke my right collarbone.
Hockey was mentioned by somebody else related to "risk compensation". In terms of risk compensation, the two activities are very different.


There are only two that call out the over 25 group. There is a general trend for reduced benefit of the helmet with age.
There were only two that separated-out "over 25". But there is nothing apparent that the "over 25" group should be any different than similar groups (eg, the 15-25 group). There is nothing that specifically happens when people turn 25. The one "more risk" result is odd.


Precisely. This study we are discussing met the minimum requirement of well informed analysts. YOU can't disregard the result simply because you don't like it.

I'm not "disregarding" it. Given all the other results, it's one odd result. It would be interesting if that one odd result had an explaination. Statistically, one expects to get odd results like this once in a while (ie, rarely).

Risking muddying the waters till further, I quoted a couple of studies about the risk of serious head injuries in American Football players in high school and college on the family section. The figures quoted showed there being a greater risk for the former than the latter. Obviously, since I know relatively little about that sport, my conclusion may be suspect, but would it be because college football players have more experience, skill and strength, than high schoolers?

I'm assuming that the helmets worn by both groups are pretty much the same so the differences in injury/fatality rates are caused by other, human, factors?

I think it's safe to say that behavior is a greater factor in risk reduction.

Equipment just isn't as effective.

Hockey was mentioned by somebody else related to "risk compensation". In terms of risk compensation, the two activities are very different.


Yeah, your comment just tickled me (as in made me laugh) a bit because of the symmetry of my two sports injuries.




There were only two that separated-out "over 25". But there is nothing apparent that the "over 25" group should be any different than similar groups (eg, the 15-25 group). There is nothing that specifically happens when people turn 25. The one "more risk" result is odd.


I'm not "disregarding" it. Given all the other results, it's one odd result. It would be interesting if that one odd result had an explanation. Statistically, one expects to get odd results like this once in a while (ie, rarely).

Ummm. While there is no specific event that happens at 25 there is the effect that older people have had more chance to become skilled in whatever sport they are participating in. Older skiers, as a group, have less of the fall down go boom kinds of accidents that children have. Older cyclists, as a group, have less of the fall down go boom kinds of accidents that children have. Since children are having more of those fall down go boom kinds of accidents, they benefit disproportionately from the use of safety equipment designed to mitigate those kinds of accidents. Among the older skilled skiers, having fewer of the fall down go boom accidents, the helmets are not helping as much. But the helmets may have the undesirable effect of encouraging the older skier to take more risks. Remember the Bell ads: "Courage for your head!". So there is a potential cause for the effect seen in that study.

A good discussion of the risk homeostasis involved with ski helmets can be found here (http://www.lidsonkids.org/ski-or-snowboard-as-if-youre-not-wearing-one.asp).

(edit) Also, it is incorrect to think of that result as a statistical outlier. It is NOT a single sample. It is itself a statistic and it has a mean that indicates higher risk, with a confidence region that largely occupies the increased risk region. (/edit)

Speedo

Ummm. While there is no specific event that happens at 25 there is the effect that older people have had more chance to become skilled in whatever sport they are participating in. Older skiers, as a group, have less of the fall down go boom kinds of accidents that children have. Older cyclists, as a group, have less of the fall down go boom kinds of accidents that children have. Since children are having more of those fall down go boom kinds of accidents, they benefit disproportionately from the use of safety equipment designed to mitigate those kinds of accidents. Among the older skilled skiers, having fewer of the fall down go boom accidents, the helmets are not helping as much.
Yes, it doesn't make sense to lump children with adults. But 15 year-olds are not "children". And every non-child subgroup except for one show a decrease. Keep in mind that the two >25 groups are not the only groups with people >25.

Note that the statistic being analysed is the relative rate of injury within a subgroup. That is, the analysis takes into account (somewhat) the possibilty that different subgroups might have different injury rates. The thing being compared is head-injury rates with/without helmets within a subgroup. And there is only one example of "enhanced" injuries with helmets.


But the helmets may have the undesirable effect of encouraging the older skier to take more risks. Remember the Bell ads: "Courage for your head!". So there is a potential cause for the effect seen in that study.
Why would only older people take "more risks"? It's certainly not unknown for younger people to take all sorts of risks that people >25 would be much less inclined to take. Older skiers might be more risk adverse too. Nor is this hypothesis well-supported by one result out of 50.


A good discussion of the risk homeostasis involved with ski helmets can be found here (http://www.lidsonkids.org/ski-or-snowboard-as-if-youre-not-wearing-one.asp).
Yes, there is lots of speculation.


We cannot say that wearing a helmet makes you ski faster (it may be that people who tend to ski fast are the ones who buy and use helmets)



(edit) Also, it is incorrect to think of that result as a statistical outlier. It is NOT a single sample. It is itself a statistic and it has a mean that indicates higher risk, with a confidence region that largely occupies the increased risk region. (/edit)
Averages computed from small samples of the overall population have variation also (standard error of the mean). That is, it's possible that it is a statistical outlier. Also, it happens to be very different than all the other results. It certainly is possible that there is a real difference and that something explains it.

Yes, it doesn't make sense to lump children with adults. But 15 year-olds are not "children". And every non-child subgroup except for one show a decrease. Keep in mind that the two >25 groups are not the only groups with people >25.


And 15 year olds are not adults either. Since this is a meta-data study, they can't use the groupings they might desire, they can only use the groupings that exist in the studies from which they drew information. There may have been adults in the other groups, but since those studies did not call out results on the basis of age we don't know what they had to say on the subject. The absence of information from the other studies is not information.



Note that the statistic being analysed is the relative rate of injury within a subgroup. That is, the analysis takes into account (somewhat) the possibilty that different subgroups might have different injury rates. The thing being compared is head-injury rates with/without helmets within a subgroup. And there is only one example of "enhanced" injuries with helmets.


But my observation was about a >25 year old subgroup, so you can only compare the results of other matching groupings. So it's 50-50.



Why would only older people take "more risks"? It's certainly not unknown for younger people to take all sorts of risks that people >25 would be much less inclined to take. Older skiers might be more risk adverse too. Nor is this hypothesis well-supported by one result out of 50.


An older person might take more risks than he or she otherwise would under the impression that their safety equipment will compensate for their risky behavior.



Yes, there is lots of speculation.


Uh, that guy's not just blowing smoke. Did you read his bio?

Jasper Shealy, PhD, has been studying ski injuries for 30 years and snowboard injuries for 15 years. His interest in head injuries in skiing and helmets stems from the Sugarbush Resort in Vermont, where he has been a co-researcher with Dr. Robert Johnson and Carl Ettlinger for more than 20 years. Dr. Shealy is currently the chair of the ASTM F27 Committee for snow skiing, and is a U.S. technical delegate for International Standards Organization (ISO) standards relating to snow skiing.

When you and I talk about this it can be classified as speculation. But the discussion referenced is backed up by a substantial body of work in the specific area we are discussing.



Averages computed from small samples of the overall population have variation also (standard error of the mean). That is, it's possible that it is a statistical outlier. Also, it happens to be very different than all the other results. It certainly is possible that there is a real difference and that something explains it.

Yes, and the paper quoted the 95% confidence region so that we understood that possibility. The mean was 1.13 which indicates increased risk. The 95% confidence region was 0.93 to 1.36. So the author of the original study is telling us that based on the sample size and the study methodology, he believes that the probability of being outside the range of 0.93 to 1.36 is 5%. Most of that confidence region, anything above 1, indicates increased risk. It's not just some random outlier that you can ignore.

Speedo

And 15 year olds are not adults either.
It wasn't a group of just 15 year olds (the 15-25 group). And there are the >20 yr skiing and >20 yr snowboarding groups (and one of the two >25 groups). Why would these group be radically different than the one >25 group?


Since this is a meta-data study, they can't use the groupings they might desire, they can only use the groupings that exist in the studies from which they drew information. There may have been adults in the other groups, but since those studies did not call out results on the basis of age we don't know what they had to say on the subject. The absence of information from the other studies is not information.
Well, it seems equally "absent of information" to assume that the groups were composed of young children. I'd expect that only a small percentage of people at a ski resort are young children. It isn't unreasonable to expect that these "ageless" groups are composed mostly of adults.


But my observation was about a >25 year old subgroup, so you can only compare the results of other matching groupings. So it's 50-50.
And there are the >20 yr skiing and >20 yr snowboarding groups. So, it's more like 1:4.


An older person might take more risks than he or she otherwise would under the impression that their safety equipment will compensate for their risky behavior.
Then, so might anybody. So might the "expert" group. What is special about this one odd group? Note that the "Park/off-piste (backcountry or out of bounds)" (ie, "risky" skiing/snowboarding) showed a relative number of 0.26 (the third lowest number). (These two groups really should not have been lumped together.)

(I take it you don't ski.)


Uh, that guy's not just blowing smoke. Did you read his bio?
He basically admitted that the "risk compensation" hypothesis wasn't more than a hypothesis.


Yes, and the paper quoted the 95% confidence region so that we understood that possibility. The mean was 1.13 which indicates increased risk. The 95% confidence region was 0.93 to 1.36.
We have 1/50 that shows an odd result. That is, the presence of one outlier isn't unexpected.


So the author of the original study is telling us that based on the sample size and the study methodology, he believes that the probability of being outside the range of 0.93 to 1.36 is 5%. Most of that confidence region, anything above 1, indicates increased risk. It's not just some random outlier that you can ignore.
No, the original author is just providing the results of a calculation based on the sample size he had and the result he got from that population.

It's well-understood that a particular average and the standard deviation has some probability of being wrong. The fact that there are 49 other studies that show a decrease implies that that one result is unusual.

In Tony Gwynn's twenty years playing for the San Diego Padres, he once hit .289 for a single season.

You wouldn't argue that makes Tony Gwynn a .289 hitter, would you?

No? Then what is it?

A random outlier.

Because in any set of collections of random events, there will be outliers like that.

Fatality. (http://ottawa.ctv.ca/servlet/an/local/CTVNews/20100204/OTT_Girl_Ski_Fatal_100204/20100204/?hub=OttawaHome)

Get ready for the hordes claiming helmets don't help.

I also don't see how "risk compensation" applies to cyclists with respect to helmets, because unlike in most other endeavours where helmets are common, it's almost impossible for a helmet to help a cyclist do any cycling-related act better in a way that helps the the cycling results.

In other words, when a helmet comes into play when you're cycling, you're already screwed because you're probably flying off your bike anyway.

That's in marked contrast to a sport like hockey, where a helmeted player would be a lot more likely to dive in front of a slap shot, for example. Or American football, where a player without a facemask would be a lot more restrained in his efforts to block a kick. Or even baseball - who's going to "take one for the team" off his noggin without a helmet even when the pitcher is throwing even 60 MPH curveballs?

A helmet doesn't protect a cyclist in the course of cycling - it only protects a cyclist AFTER a failure of some sort in the cycling. So it really can't have as much of an impact on any risk assessment done by a cyclist when compared to other sports. A helmet doesn't really effect a racer's chances of pulling off a risky move successfully.

In Tony Gwynn's twenty years playing for the San Diego Padres, he once hit .289 for a single season.

You wouldn't argue that makes Tony Gwynn a .289 hitter, would you?

No? Then what is it?

A random outlier.

Because in any set of collections of random events, there will be outliers like that.

I would argue, with no fear of contradiction at all, that for the 1982 season Tony Gwynn was a 0.289 hitter. It was his first season in the big leagues. It is incorrect to view that year as a statistical outlier. The Tony Gwynn that hit 0.289 in 1982 is not the same Tony Gywnn that hit 0.394 in 1994 in the middle years of his career when he was at the peak of his powers. Tony Gwynn's 1982 season is not a random outlier.

Speedo

Fatality. (http://ottawa.ctv.ca/servlet/an/local/CTVNews/20100204/OTT_Girl_Ski_Fatal_100204/20100204/?hub=OttawaHome)

Get ready for the hordes claiming helmets don't help.

Huh? Of course it helped. If she hadn't been wearing it she would have died.

I wonder what percentage reduction in head injuries could be achieved by a metastudy of topless downhill tobogganning?

http://www.independent.ie/multimedia/archive/00498/topless2_getty_498166t.jpg

Albino walrus?