Inflatable helmet, really

On Sun, 12 Sep 2010 11:36:02 -0700 (PDT), in rec.bicycles.tech Frank
Krygowski wrote:


There's some very twisted logic in that post!

For a much better parallel to typical helmet promotion: Medical
science has found no anti-cancer benefit for huge doses of vitamin C,
Linus Pauling notwithstanding.
http://www.quackwatch.com/01Quackery...s/pauling.html
Are you saying that despite such data, we should still promote vitamin
C as the most important defense against cancer? Are you saying that
even if we don't, that any particular individual is justified in
believing that vitamin C will prevent or cure their cancer?

The logic generally used in medical and health science is, if tests
show something to be ineffective, don't pretend it's effective. Move
on.

I'll also add, logic also says if data shows a problem to be
minuscule, don't over overemphasize it. Granted, that one is much
more frequently violated.

Here we have a case where people seem to be pretending cycling causes
lots of serious head injuries, more than other activities, despite
data to the contrary. And they're pretending that helmets are usually
very effective in preventing those head injuries, despite data to the
contrary.

- Frank Krygowski

Paragraph 1:
H1: The treatment population receiving huge doses of vitamin C will
have fewer cancers than the control group.

H0: There is no difference between the treatment group and the control
group that cannot be explained by pure chance beyond a probability =
0.05.

They run their T tests and that probability that any difference may be
purely luck is running in the 0.3s. What do the researchers do,
Frank?

A: They should accept the null hypothesis (H0).
B: They should conclude that they cannot reject the null hypothesis.

The correct response is 'B'.



Paragraph 2: "The logic generally used in medical and health science
is, if tests show something to be ineffective, don't pretend it's
effective."

Absolutely not! Didn't you have a freshman class in statistics,
Frank? I thought these were required. The logic generally used in
medical and health science is, if tests do not show something to be
effective, then make no statement at all. ("Effective" could also be
negative... e.g. a very effective poison.)




Paragraph 3: Not to start a grammar flame, Frank, but "data shows" is
incorrect. "Data" is a plural noun; the singular is: "datum".

Your logic might say that; however, statistics don't. Besides, that
tack doesn't address either your point or mine.




Paragraph 4: I don't have a clue why you would say that in response
to my posting. I said that failing to reject the null hypothesis does
*not* support the conclusion that the null hypothesis is a fact.
*That* is my point.

Learn to target your writing and you'll be more effective, Frank.
Don't claim I said things I never said... I know what I said and I
have never claimed that "cycling causes lots of serious head injuries,
more than other activities..." So quit changing my points into
something easily attacked. That tactic has a name, Frank; it's known
as "pummeling the straw man".

Jones

"!Jones" wrote in message
...
On Sun, 12 Sep 2010 11:36:02 -0700 (PDT), in rec.bicycles.tech Frank
Krygowski wrote:


There's some very twisted logic in that post!

For a much better parallel to typical helmet promotion: Medical
science has found no anti-cancer benefit for huge doses of vitamin C,
Linus Pauling notwithstanding.
http://www.quackwatch.com/01Quackery...s/pauling.html
Are you saying that despite such data, we should still promote vitamin
C as the most important defense against cancer? Are you saying that
even if we don't, that any particular individual is justified in
believing that vitamin C will prevent or cure their cancer?

The logic generally used in medical and health science is, if tests
show something to be ineffective, don't pretend it's effective. Move
on.

I'll also add, logic also says if data shows a problem to be
minuscule, don't over overemphasize it. Granted, that one is much
more frequently violated.

Here we have a case where people seem to be pretending cycling causes
lots of serious head injuries, more than other activities, despite
data to the contrary. And they're pretending that helmets are usually
very effective in preventing those head injuries, despite data to the
contrary.

- Frank Krygowski

Paragraph 1:
H1: The treatment population receiving huge doses of vitamin C will
have fewer cancers than the control group.

H0: There is no difference between the treatment group and the control
group that cannot be explained by pure chance beyond a probability =
0.05.

They run their T tests and that probability that any difference may be
purely luck is running in the 0.3s. What do the researchers do,
Frank?

A: They should accept the null hypothesis (H0).
B: They should conclude that they cannot reject the null hypothesis.

The correct response is 'B'.



Paragraph 2: "The logic generally used in medical and health science
is, if tests show something to be ineffective, don't pretend it's
effective."

Absolutely not! Didn't you have a freshman class in statistics,
Frank? I thought these were required. The logic generally used in
medical and health science is, if tests do not show something to be
effective, then make no statement at all. ("Effective" could also be
negative... e.g. a very effective poison.)




Paragraph 3: Not to start a grammar flame, Frank, but "data shows" is
incorrect. "Data" is a plural noun; the singular is: "datum".

Your logic might say that; however, statistics don't. Besides, that
tack doesn't address either your point or mine.




Paragraph 4: I don't have a clue why you would say that in response
to my posting. I said that failing to reject the null hypothesis does
*not* support the conclusion that the null hypothesis is a fact.
*That* is my point.

Learn to target your writing and you'll be more effective, Frank.
Don't claim I said things I never said... I know what I said and I
have never claimed that "cycling causes lots of serious head injuries,
more than other activities..." So quit changing my points into
something easily attacked. That tactic has a name, Frank; it's known
as "pummeling the straw man".

Jones

And what you just did also has a name: "pulling Frank's covers".

Bill "it's amazing he hasn't shivered to death by now" S.

On Sun, 12 Sep 2010 13:18:03 -0700, in rec.bicycles.tech "Bill
Sornson" wrote:

And what you just did also has a name: "pulling Frank's covers".

Bill "it's amazing he hasn't shivered to death by now" S.

Well, the truth hurts, but there it is. I do have some troll
tendencies, I admit.

I was actually surprised at the high vitriol level this discussion
produces; I haven't seen anything like it on Usenet for at least half
an hour... maybe longer! I do also admit that I resent being mandated
to wear a helmet, particularly, when the rider of a motorcycle does
not... thus, I always cut my bicycle right in front of 'em every
chance I get.

Jones

On 9/12/2010 3:47 PM, !Jones wrote:
On Sun, 12 Sep 2010 13:18:03 -0700, in rec.bicycles.tech "Bill
wrote:

And what you just did also has a name: "pulling Frank's covers".

Bill "it's amazing he hasn't shivered to death by now" S.

Well, the truth hurts, but there it is. I do have some troll
tendencies, I admit.

I was actually surprised at the high vitriol level this discussion
produces;[...]

As ye sow, so shall ye reap.

--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.

On Sun, 12 Sep 2010 15:53:52 -0500, in rec.bicycles.tech Tom Sherman
°_° wrote:

Well, the truth hurts, but there it is. I do have some troll
tendencies, I admit.

I was actually surprised at the high vitriol level this discussion
produces;[...]

As ye sow, so shall ye reap.

So, what are you gonna do, Tom? Flame me? That's akin to suing a
lawyer for being a litigious shyster.

Hey, check this out!

http://www.bhsi.org/nhtsasurveyextract.pdf

See figure 13.

So, there it it! Wearing a bicycle helmet occasionally causes your
income to increase by 12%. If you wear one on *every* trip, you have
a 31% probability of making over $75,000

I wonder if it'll help me pick up women? The helmet probably won't,
but the extra bucks in me pocket certainly couldn't hurt, I say!

Jones

On Sep 12, 11:16 am, Frank Krygowski wrote:
On Sep 12, 1:31 am, Dan O wrote:



On Sep 11, 10:01 pm, Frank Krygowski wrote:

On Sep 11, 5:43 pm, Dan O wrote:

On Sep 11, 12:36 pm, Frank Krygowski wrote:

Others here have defended that 14 mph, saying that all you need to
worry about is the perpendicular component - and pretending that
cyclists never run into cars, I suppose. However, if the issue is
angular acceleration caused by a grazing impact between the helmet and
the ground, then the cyclist's forward speed definitely makes a
difference. It's a simple vector problem.

So if the vector sum of your forward speed and your head's vertical
drop speed is less than 6.5 mph, that paper's findings probably apply
to you. I'll let you guys take a crack at the math to find the
limiting forward speed.

Dumbass, attenuation is attenuation.

Couldn't do the math, I see!

What math? I'm not designing helmets, or designing tests for them.

Go ahead, dumbass - define the problem. I will solve it for you.

Given: that much of the data in the cited paper involved a total
impact velocity (helmet to ground) of only 6.5 mph; and given that
according to the CPSC helmet standard, an appropriate vertical
component of that impact velocity is 14 mph;
Find: the horizontal travel velocity which will limit the total impact
velocity to 6.5 mph. Or hell, to 8.5 mph (the other velocity in that
test) if you prefer.

Sorry, I still don't understand the problem. How can the impact
velocity be less than the vertical component? (Maybe there is missing
information?) I am interested if you want to show me how to solve it,
though.


Bonus: Explain to us whether you normally ride faster or slower than
the velocity you calculate.


What I was saying is that, in my many crash experiences, my head
generally doesn't smack into anything at anywhere near the speed I was
moving before I crashed.

Also, that paper:

http://www.bhsi.org/hodgstud.pdf

.... seems to show that lower impact angles result in lower impact
forces (which only makes sense). It seems to me that crashing at
higher horizontal velocity would result in lower impact angle with the
ground (not that faster is better in a crash overall - just sayin' :-)

(Although, my experience e.g. skipping stones across the water tells
me that faster is better in terms of overcoming friction.)

On 9/12/2010 4:59 PM, Dan 0verm@n wrote:
On Sep 12, 11:16 am, Frank wrote:
On Sep 12, 1:31 am, Dan wrote:



On Sep 11, 10:01 pm, Frank wrote:

On Sep 11, 5:43 pm, Dan wrote:

On Sep 11, 12:36 pm, Frank wrote:

Others here have defended that 14 mph, saying that all you need to
worry about is the perpendicular component - and pretending that
cyclists never run into cars, I suppose. However, if the issue is
angular acceleration caused by a grazing impact between the helmet and
the ground, then the cyclist's forward speed definitely makes a
difference. It's a simple vector problem.

So if the vector sum of your forward speed and your head's vertical
drop speed is less than 6.5 mph, that paper's findings probably apply
to you. I'll let you guys take a crack at the math to find the
limiting forward speed.

Dumbass, attenuation is attenuation.

Couldn't do the math, I see!

What math? I'm not designing helmets, or designing tests for them.

Go ahead, dumbass - define the problem. I will solve it for you.

Given: that much of the data in the cited paper involved a total
impact velocity (helmet to ground) of only 6.5 mph; and given that
according to the CPSC helmet standard, an appropriate vertical
component of that impact velocity is 14 mph;
Find: the horizontal travel velocity which will limit the total impact
velocity to 6.5 mph. Or hell, to 8.5 mph (the other velocity in that
test) if you prefer.

Sorry, I still don't understand the problem. How can the impact
velocity be less than the vertical component? (Maybe there is missing
information?) I am interested if you want to show me how to solve it,
though.

You solve the problem by riding a lowracer, so the vertical component is
6.5 mph or less. So if I fall over when barely moving forward on my
lowracer with its 12-inch seat height, the bicycle foam hat might
provided adequate protection.

Bonus: Explain to us whether you normally ride faster or slower than
the velocity you calculate.

It is hard to ride at a velocity v * i (where v is forward speed).

--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.

On Sep 11, 12:41*pm, Frank Krygowski wrote:
On Sep 10, 4:59*pm, James wrote:
Maybe your Unliddedness has let your eyesight degrade. *I posted a
link. *MikeWhy found it. *Strangely you overlooked it. *Maybe, like so
much else you didn't like the message it brought and chose to sweep it
under the carpet and respond with more rubbish.

What utter bull****! *Did you even bother to read that paper?

Nope. CBF. Was waiting for you.

There
was no mention anywhere in the paper of the coefficient of friction of
a bare head on pavement in a typical crash.

Oh, what a shame. At least there was for helmets.

While I'm at it, the paper - intended to show that most helmets won't
impart too much rotational acceleration - tested impacts at a
_maximum_ speed of less than 9 mph, to protect the crash test dummy.
Much of its data was gathered at only 6.5 mph, and some even lower.
There is no evidence its measurements are valid at any higher speed.

Yeah, I read on some other study that they found helmets increased
rotational acceleration when they hit the dummy on the chin. Not sure
why they were boxing with it and not crashing it.

I guess we'll never know how a bare head sticks to the road until you
strap on an accelerometer and dab the road, Frank. Until then, you
have no way of knowing whether a helmet increases the risk of
rotational injury or not.

BUT! *If you are on board with that test's results, I assume you also
approve of the recommendation to fit clear face masks to bike
helmets?

Sounds like a great idea, especially for offroadies in the mud! You
should promote such an idea.

JS.

On Sep 12, 10:07*pm, !Jones wrote:
Hey, check this out!

http://www.bhsi.org/nhtsasurveyextract.pdf

See figure 13.

So, there it it! *Wearing a bicycle helmet occasionally causes your
income to increase by 12%. *If you wear one on *every* trip, you have
a 31% probability of making over $75,000

Or, more precisely, if you're a high earner, you're more likely to
have the brains to put on your helmet when you ride bike.

An interesting corollary is that the anti-helmet zealots will mostly
fall into the lower socio-economic brackets. Can't say I find that
surprising; one can conclude that much without any statistics simply
from observing their grim manners.

AJ

On 9/12/2010 7:16 PM, André Jute wrote:
snip blah, blah, blah [1]

See
http://en.wikipedia.org/w/index.php?title=Bandon%2C_County_Cork&diff=prev&ol did=165003918.

Scroll down to "People".

[1] For André Jute and Michael Press, this is NOT a quote of previously
posted text.

--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.