published helmet research - not troll

Frank Krygowski writes:

Bill Z. wrote:

Frank Krygowski writes:

Can you at least agree that the most common claim, that helmets cause
an "85% reduction in head injuries," is actually wrong?
I never said it was right at any time during the previous discussion
over the last 10 years, so why did you say "at least"? Sorry
Krgyowski, you'll have to refrain from "when did you stop beating your
wife" questions before I'll answer such questions.

I said "At least" because I can't recall you ever saying _anything_
that wasn't in favor of helmets, except that you're against adult
MHLs. But if you require it, I'll remove the phrase "at least."

You mean like saying that helmets provide some useful protection but
are not a panacea (or something very similar to that)? That's probably
the strongest statement I made in favor of helmets. Otherwise I've
merely objected to all the anti-helmet BS.

You'll also have to state what you mean by an 85% reduction.

It's not what I mean that's at issue. "85% reduction in head
injuries" is the figure that's quoted in more than half of the helmet
promotion literature. The issue is what _they_ mean - and whether you
agree with them.

No, it is what *you* mean that we are talking about. If you think
manufacturers are putting out misleading advertising, report them to
the FTC.

So, can you agree that the most common claim, that helmets cause an
"85% reduction in head injuries," is actually wrong?

Or do you feel a need to avoid even this simple question?

Your question is ambiguously worded. Clean it up first so I can
figure out what you are asking. If I given you an answer for all
injuries, no matter how minor, you'll probably morph it into a claim
about fatalities.

--
My real name backwards: nemuaZ lliB

"Riley Geary" writes:

"Bill Z." wrote in message
...


And what evidence do you have that, in any significant number, people
in these states stopped wearing helmets when the law was repealed?

??? It's perfectly clear from FARS data that this is precisely what
happened. TX plunged from an average 75% helmet use rate among fatally
injured motorcyclists prior to repeal to just 29% as of 2001-02; LA went
from 74% to 32%; FL fell from 86% to 33%; and even AR declined from ~65% to
31% (though AR helmet use data does not appear to be all that reliable
compared to most other states).

I was asking about usage rates in general, not rates for only fatally
injured motorcyclists.


--
My real name backwards: nemuaZ lliB

"Just zis Guy, you know?" writes:

On Sun, 25 Jul 2004 22:04:18 GMT, (Bill Z.)
wrote in message :


And in what way will a helmet reduce the rotational forces? Hint: it
can't.

Yes it can - a helmet reduces the force by spreading the impact over a
somewhat longer time.

Ah, so you didn't understand. Thought not.

Wrong. As you've shown before, you simply do not understand physics.

A substantial impact to the head that is "off center" will apply a far
higher torque than you can possibly be counteracted by your neck
muscles. Also, the energy and momentum transferred will propagate
through the skull. If the impact is not directed towards the brain's
center of mass, the brain will start to rotate (or at least "try" to.)

Read up on some fluid dynamics.

--
My real name backwards: nemuaZ lliB

"Just zis Guy, you know?" writes:

On Sun, 25 Jul 2004 22:15:08 GMT, (Bill Z.)
wrote in message :

Note to readers: what Bill is sayng here is that they were praised a
decade ago because they were honest enough to say *the same data*
showed no benefit.

They simply reported a null result (a failure to detect something).
They subsequently improved on their previous work.

A difference which makes no difference is no difference.

Ever here of statistical error?

Unlike you, I live in the U.S. The major increase in helmet use
roughly coincided with a huge increase in the number of SUVs and vans
on the roads. In a collision, a cyclist stands a much higher chance
in an accident of hitting his or her head in the primary impact with a
motor vehicle than when vehicles were smaller.

And your citation for this is? Bearing in mind that there is a
similar growth in the number of SUVs in the UK, albeit delayed by a
couple of years, and no such increase is visible here...

Have you ever looked at an SUV? Ride next to one and see if you
can peer over the top.

There are also demographic changes with a mini baby boom following a
baby bust after the big baby boom that followed WW-II, and a host of
other factors. For example, at least around where I live, drivers
have gotten progressively worse, over the past 20 years, with more
and more stop sign and red-light running than before.

And your citation for this is? Bearing in mind that there was a
similar demographic change in the UK and no such increase is visible
here...

Personal observation. When I moved to California, if you even looked
like you wanted to cross the street at a crosswalk, drivers would
stop. Now they speed up. They regularly run red lights. The drivers
are simply far more eratic.

If you need to see a constributing factor, plot a graph of traffic
levels versus the number of CHP officers patrolling the highways,
over the last 30 years or so.


Ever heard of Occam's Razor? The simplest explanation is the one to
choose. In this case: helmets make no meaningful difference to
serious or fatal injuries.

The simplest explanation has nothing to do with helmets.

--
My real name backwards: nemuaZ lliB

"Just zis Guy, you know?" writes:

On Sun, 25 Jul 2004 22:01:34 GMT, (Bill Z.)
wrote in message :

Interestingly, there was a front-page story in one of the safety
journals (I think it was American Journal of Public Health, but my
memory may be at fault there) decryignt he rise in motorcyclist
fatailities following repeal of helmet laws in some states.

Journals (at least, real ones) do not have front page articles.
Perhaps you meant a short editorial that sometimes appears. In
any case, the order in which articles appear in a journal in most
cases does not reflect the editors' opinion of the articles.

Big chart on the front page "pictures at eleven" style presentation.
I have a scan of the fornt page somewhere, but I've lent the book
which contains this information to someone at work.

The journals I read have the same sort of cover from issue to issue,
not "pictures at eleven." Are you sure you mean a journal and not
a magazine?


And what evidence do you have that, in any significant number, people
in these states stopped wearing helmets when the law was repealed?

About as much evidence as I have for motorcycle helmets having worked
in the first place: none at all :-)

Note to the disinterested: the UK motorcyclist fatality rate rose
relative to all other road users in the two years following the helmet
law.

What probably happened is that the legislators in a few states found
that they had solved a non-problem

I think we should frame that and hang it on the wall. Guess what?
Bicycle helmet laws are a solution to a non-problem, too - only
problem is they are actually a non-solution to a non-problem :-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

--
My real name backwards: nemuaZ lliB

"Just zis Guy, you know?" writes:

On Sun, 25 Jul 2004 22:20:21 GMT, (Bill Z.)
wrote in message :

The class of studies that Kunich refers to do not measure head injury
reductions, where a serious head injury is turned into a less serious
head injury (but a serious injury nontheless.)

No indeed. They measure the overall level of serious and fatal head
injuries in a whole population, over time. Which is not correlated
with helmet use.

Which is a serious shortcoming. If you have a distribution of injuries
(represented below by a series of '*' in order of severity) and shift
them by some safety measure that mitigates but does not compeletely
prevent most injuries, you see something like the following.

******************************************
. |
******************************************

If the '|' denotes the threshold below which you'd declare the
injury no longer serious, all you'd be hard pressed to pull the
signal out of the noise, even though there was a useful reduction
in severity in each case.

If the change in head injury rates is not measurable when wearing
rates change from around 40% to not far short of 100% over a couple of
years, as they did in New Zealand, then Occam's Razor suggests that
you start from the assumption that the helmets do not make any
meaningful difference to the injuries being measured, which are
serious and fatal injuries.

Oh come off it. Look up how many fatalities you have per year in
New Zealand (Hint: it is around 800 in the U.S. so if you scale by
population, you get a pretty small number.) You'd need a huge
reduction in the fatality rate to detect anything at all. You'll
have similar problems with "serious injury" rates due to the effect
I mentioned. It has nothing to do with Occam's Razor - it is merely
a question of the difficulty of measuring anything at all with such
small samples.

But it's important to remember that the claims made for helmets are of
the order of 2/3 or more of *serious* injuries prevented (you can't
get a law passed if it only prevents trivial injuries).

I haven't made such claims, but you do have to be careful about
distinguish "2/3 prevented" from "a reduction in the level of injury
in 2/3 of the cases."


You should also remember that one of the greatest indicators for
cyclist safety is numbers cycling. Helmet laws are always associated
with substantial drops in the numbers cycling.

You mean that as traffic conditions get worse, people stop cycling?
And this is surprising? :-)


--
My real name backwards: nemuaZ lliB

"Tom Kunich" writes:

"Bill Z." wrote in message
...

Unlike you, I live in the U.S. The major increase in helmet use
roughly coincided with a huge increase in the number of SUVs and vans
on the roads.

The van craze peaked from about 1988 to 1995. There were never that many
vans on the road and certainly very few vans were involved in hitting and
killing cyclists. The SUV's happened WAY after helmets were on the vast
majority of bicyclists.

What Kunich is trying to say is that they started a van craze, followed
by an SUV craze, but let's ignore the fact that both are large, boxy
vehicles that you can't see over.

The question really is why Zaumen would come up with this perfectly
rediculous claim without the slightest data to back it up.

The liar needed to say something, so he is pretending to deny what is
simply common knowledge.


--
My real name backwards: nemuaZ lliB

"Tom Kunich" writes:

"Bill Z." wrote in message
...

Over the past decade, you've claimed that *every* paper that showed a
positive result for helmet effectiveness, no matter how small, was
"flawed" and that every paper that showed a negative result (i.e, failed
to measure anything) is a paragon of virtual.

Since everyone else who have read the papers agree that the positives are
flawed perhaps you ought to read them yourself.

Uh huh. You don't know what I've read, but in your case "everyone" seems
to be meant to include just the usual suspects, plus Guy who is a new
addition to your camp.

rest of this bozo's garbage snipped.

--
My real name backwards: nemuaZ lliB

"Bill Z." wrote in message
...
Frank Krygowski writes:

[...]
It's not what I mean that's at issue. "85% reduction in head
injuries" is the figure that's quoted in more than half of the helmet
promotion literature. The issue is what _they_ mean - and whether you
agree with them.

No, it is what *you* mean that we are talking about. If you think
manufacturers are putting out misleading advertising, report them to
the FTC.

So, can you agree that the most common claim, that helmets cause an
"85% reduction in head injuries," is actually wrong?

Or do you feel a need to avoid even this simple question?

Your question is ambiguously worded. Clean it up first so I can
figure out what you are asking. If I given you an answer for all
injuries, no matter how minor, you'll probably morph it into a claim
about fatalities.

--
My real name backwards: nemuaZ lliB

Let me take a stab at this--can you reject as clearly wrong either or both
of the following formulations:
1) helmets cause an "85% reduction in _fatal_ head and/or brain injuries"?
or
2) helmets cause an "85% reduction in bicycling _fatalities_"?

Riley Geary

There is little argument that helmets can protect riders from some
head injuries in bicycle crashes. Even the comfort and style
complaints don't hold as much weight as they used to.

It's like cigarette smoking outdoors. Cycling without a helmet is most
dangerous to the user, with everyone else picking up increased
insurance rates due to this selfishness. Smoking outdoors is mostly
just dangerous (long term health) to the user.

I don't get uspet when I see either a smoker or a rider without
helmet. I rarely do either, myself.

crit pro