My helmet saved me, and broke

On Wed, 31 Aug 2005 16:59:26 -0500, johnfoss wrote:

Ian Smith wrote:
*In what way is giving an answer that your are almost certain is wrong
useful?*

It shows you gave it a try. In school, "I don't know" is seldom an
acceptable answer on any test.

In school, questions are normally formulated with enough care that
it's possible to reach an answer with a reasonable probability of
being correct. The real world is rarely like questions in school. I
don't think your observation has any relevance.

Notice I said intelligent, not correct. There is no correct answer for a
question for which you don't know all the variables. But in life it's
okay to guess.

It is also OK to admit, if you don't know, that you don't know. If
there is so little information available that teh answer is going to
have a very poor likelihood of being correct or near correct, I
believe it is better to highlight that than to pretend non-existent
knowledge.

I also notice that you have not answered the question I asked, being
"in what way is giving an answer that you are almost certain is wrong
useful?"

Why are you apparently so scared of admitting that you don't know?
More to the point, why are you so scared of me admitting that I don't
know the answer to various question? Not only am I not allowed to not
know about steveyo's accident, I'm also not allowed to not know about
teh effects of bullet-proof vests, what else?

regards, Ian SMith
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On Wed, 31 Aug 2005 16:42:51 -0500, johnfoss wrote:

Obviously a slow day at work...Ian Smith wrote:

[actually, the attributions were scrambled again. I've fixed who
said what (John said '', I said '' prefixed lines). The dates are
wrong in soem cases - teher's at least four levels of quoting here
really]

*Because there are plenty of situations that meet the situation as
described, in which a helmet would make matters worse. To decide
you'd definitely prefer a helmet in those situations would be
irrational.*

The intended assumption here is that we're talking about Steveyo's fall,
as described at the beginning of the thread.

Not being a mind-reader I can only respond to what you write, not what
you intended.

I've tried to be more specific in the specific case of steveyo's fall
- his injuries would have been different, there is a good chance they
would not have been significantly different (but I don't know), I
personally do not expect that he'd have been ksi without the helmet.

I believe the same to be true for much riding in general. That the
helmet will do more good than harm, or be irrelevant, in the vast
majority of crashes. The studies I have looked at showed increased
numbers of accidents (are these only ksi accidents?),

I don't know what studies you have looked at. Most studies consider
only ksi-type accidents, because they are the only ones there are
remotely accurate figures for. In the UK, for example, traffic
accident reporting is via. the police, so ONLY if the police get
involved will the incident get into the traffic statistics. The
police aren't interested in minor injury or damage events - they
prefer you just get the insurance companies to sort it out.

Some studies use hospital and/or A&E (which I think is termed 'ER' in
America) records, but that's a less reliable approach for reasons
including self-selection and so on.

Either way, minor injuries don't get into the studies.

*...to say you'd prefer to be wearing a helmet in
all such situations, including those where your decision will worsen
your injuries is either equally irrational, or suggests he has been
mislead (misguided) regarding the efficacy of the helmet and/or the
situations to which it is to be subjected.*

Only if it is known that he has *a 50% or greater chance* of his helmet
worsening his problems. I have not seen this to be the case.

Not so. Firstly, in the hypothetical circumstance I was describing,
the person knows exactly whether the helmet will worsen or mitigate
the injuries.

The more significant point relates to the trade-off between
probability and severity. Imagine an accident where the outcome is
uncertain. What is known is that if you don't wear a helmet you'll
suffer a graze to one cheekbone which will be painful for two days,
and no other injuries. If you wear a helmet, there is a 70% chance
that you will suffer a slightly smaller graze which will be slightly
less painful for a day and a half. There will also be a 30% chance
that you will be killed.

In this scenario, I think you would be misguided to wear a helmet,
though there's a less than 50% chance that it will worsen the
injuries. Indeed, it's more than twice as likely to improve matters
than to worsen them. I still wouldn't wear the helmet.

This scenario is relevant to helmets, because I believe helmets _are_
good at protecting against minor, painful, inconvenient but not
life-threatening head injuries. That's most of the injuries receievd
while cycling (any number of wheels). However, I think they are _not_
good at protecting against ksi injuries, and may make the most serious
ksi injuries worse. Since it's ksi injuries that are serious (by
definition) it is those that I base my decisions on, not whether the
helmet helps a bit on injuries that I will have forgotten about a
month later.

the analogous question is - in a specific accident which you don't
know about would the car passengers have been better off wearing
seatbelts?

To which an acceptable answer would be (based on my quoted numbers which
I admittedly have no handy links for) "About 98% of the time."

No, I said a SPECIFIC accident, not accidents in general, and not what
is the chance in a randomly selected accident. I was referring to
something that actually happened.

You can't say event in the past happened some percent of the time - I
just tossed a coin, did it come up heads? '50% of the time' is not a
valid answer to that specific question.

(In case you're interested, it was a malaysian 20 sen, it doesn't have
a head, it came up the picture of a box rather than the picture of a
flower).

The intention was to be talking about Steveyo's fall, which happened
while he was trying to mount, at zero miles per hour.

As previosuly noted, I am not able to respond to what you
merely intended to write.

You seem to be refusing to acknowledge that in
many cases a helmet *does* help.

Where have I done that? More misrepresentation.

Sorry. The places where you've done that are all through this
thread,

No, I have not said that. You've avoided substantiating your
misrepresentation, and in fact repeated it.

*I'm not forgetting that there are cases where they can help. I
have never said there are no cases where they help - indeed I
have often posted exactly the opposite to that.*

Not in this thread, that I've noticed (I may have missed something).

You have. I've said it again above.

The fact that I said I don't know whether a helmet would help or
worsen in a specific incident proves that I think it helps in some -
that statement would be nonsense otherwise. If I thought it never
helped, I wouldn't say I didn't know, I'd say it wouldn't help. This
is really trivial logical deduction.

to hear it from you. Now it makes me more willing to accept other things
you may say. Now you sound *a lot* more objective. This is what people
meant when referring to your style of debate.

I admit I assume that the people I am talking to are capable of
trivial logical deduction. Sorry if that upsets you.

*I don't know enough aboput bullet-proof vests to have any useful
notion of their efficacy. So the answer is "I don't know".

Sheesh. I do.

*Lucky you. As I said, I don't. I expect we can find some
things I know about and you don't. How's your knowledge of
non-linear finite element analysis?*

I'm not sure how that would help us with bullet-proof vests.

I don't think it would - I've never done high-speed impact modelling,
only impacts with things falling under gravity, max speed of impact
under 80mph or so, I'd guess. It's merely an example of something I
know about, and expect you don't know about in great detail, to
illustrate that the fact that you know something that I don't is
hardly remarkable.

I expect we can find something else - you probably know more about the
colours the walls are painted in your house than I do. Big deal.

I am not an expert on the things, never worn one, never read an
article about them.

But you were willing to assure me that you know they stop most
bullets. This is a case in point. I believe it would be more useful
to admit to knowing nothing about something I know nothing about,
rather than bull**** and make statements that might influence people
making life-affecting decisions.

You'd seem to rather say bullet-proof vests stop most bullets, because
you saw it on a TV show.

Just things one picke up from reading the newspaper and books, watching
(often fictional) TV and movies, etc.

Right. Hollywood being renowned for its accuracy in all things, of
course.

We may know less than you, but perhaps we are objective enough to take
a guess and get on with our lives. Are the studies inconclusive about
whether wearing a helmet for bicycling is better than not wearing one?

*Yes, I believe so.*

I agree with this on a societal level. But I disagree with it on a
person-by-person level.

I think it applies to both, though possibly to differuing degrees.

People should not make their helmet-wearing
choices based on information that helmet effectiveness is inconclusive. It
isn't. In one way of looking at the data, it is. I many other ways of
looking at the data, it very much isn't.

Then it IS inconclusive. It can't possibly be conclusive if it's
inconclusive when you look at it one way. If it were conclusive,
there wouldn't be room for doubt, You can't say "there's room for
doubt, but there's no room for doubt", at least, not coherently.

But sorry about that, the previous bit was based on the assumption you had
passed over my earlier post when you answered several of the later ones.

You may or may not have skipped it by accident.

There was one post you made that I missed first pass. I saw it later
and went back to it. That may have been the one you mean. There may
be another I've missed entirely, but obviously, I don'yty know that
unless it's pointed out.

And with that, it seems Ian has effectively left the building.

*I don't understand what point (if any) this is supposed to make.*

You don't seem to understand a lot of these literary phrases.

I don't recognise it as 'literary' in meaningful respect, and I agree
that there seem to be several words and phrases used in ways that are
not meaningful to me in this discussion. Perhaps you should bear in
mind that, though we speak similar languages, we are not apparently
from the same culture (a fact for which I at least am profoundly
grateful).

regards, Ian SMith
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On Wed, 31 Aug 2005 17:09:34 -0500, onewheeldave wrote:

Ian Smith wrote:

Yes I do. If you unicycle out the back of a cargo plane cruising at
35,000 feet with no parachute, a helmet will not prevent your death.
I'm willing to guarantee that, and will pay you $100 if you prove
otherwise.

Any incident featuring your head travelling above mach 12, and the
concrete remaining stationary, a helmet will not prevent your death.
I'm willing to guarantee that on the same terms. [/b]

What a shoddy line to take on a board consisting of sincere individuals,
several of whom have gone to some lengths to engage in debate with you,
in a respectful and constructive manner.

Why? I was asked to provide examples of situations where a helmet is
guaranteed to do no good. I gave two hypothetical examples.

Neither is very likely, but then, it is not very likely that steveyo
will have another accident exactly the same in all respects except
that he isn't wearing a helmet, and you considered it perfectly
reasonable that I comment on that hypothetical never-going-to-occur
situation.

Indeed, the person that I was specifically addressing, the person who
effectively challenged me to define a situation where helmets do no
good, has subsequently accepted those situations, I believe. He
certainly didn't seem offended by them.

Why is it that it is offensive for me to ask you to consider
situations that are very unlikely ever to occur, but perfectly
reasonable for you to ask me to consider situations that are very
unlikely ever to occur?

regards, Ian SMith
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On Wed, 31 Aug 2005 19:13:01 -0500, Irideonone wrote:

Ian Smith wrote:
*If you unicycle out the back of a cargo plane cruising at
35,000 feet with no parachute, a helmet will not prevent your death.
I'm willing to guarantee that, and will pay you $100 if you prove
otherwise.

Excuse me Ian but theres not nearly enough information there. And
besides the paraglider Im carrying may be useful in slowing me down to
give the helmet a chance.

If you like, I'll extend the identical guarantee to you. If it's so
obviously easy to demonstrate the good a helmet will do in that
situation, simply do it, provide convincing documentary evidence, and
I'll pay the $100. Take care to demonstrate that the helmet had a
useful effect - simply unicycling out of the plane and not being
injured is not adequate.

*Any incident featuring your head travelling above mach 12, and the
concrete remaining stationary, a helmet will not prevent your death.*

I dont see why if I were in a spacecraft travelling at mach 12 I would
be wearing a bike helmet but if I were what relevance it is that there
is some stationary concrete somewhere and Im likely, no guaranteed to
die, why?

I don't think that quite parses into english. The example is in
reference to a previous question I was asked about whether I'd rather
wear a helmet or not if my head were to strike a concrete block. If
my head is doing mach 12 (or above) and the concrete is stationary,
I'd probably not bother.

The gist of your question seems to be whether this situation is
likely. No it is not, it is extremely unlikely, I'd say. It's almost
as unlikely as steveyo falling off in a manner identical in every
respect except not wearing a helmet, and that was a hypothetical
scenario that was apparently worth discussing.

regards, Ian Smith
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Indeed, those are two situations that a helmet would certainly not help
in. But you make a mistake by saying that steveyo would probably not
have this accident again. Clearly, that's true. But what if before, his
accident, he had this accident but without a helmet. This is a
hypothetical situation, just as the ones you presented. But could still
happen. You obviously can't know exactly how this would have happened.
But say that steveyo had just read this thread, but about a different
person, and listened to you. Admittedly, you claim that you are not
saying that a helmet is useless, which I can accept. However, it comes
across strongly as if you are saying that. So steveyo goes out with his
new knowledge that helmets are "useless" and then falls, with enough
force to compress the foam on a helmet, and crack it, and this happens
to his head. What does that mean?


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Duffle
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On Wed, 31 Aug 2005 19:17:17 -0500, Irideonone wrote:

Ian Smith wrote:
*I haven't heard the phrase. *
Now you have.

But not in any situation that makes sense to me.

*I still don't think that's what you mean, *

And now you know what Im thinking?

No, that's why I asked the question I did. Until you answered the
question it seemed most likely to me that you meant "evasion", not
"aversion". Now you have answered thje question, and I know that you
consider you did not accidentally use the wrong word.

*Are you sure you didn't mean "evasion"?*

Nope.

I take that to mean "no you didn't mean evasion", rather than "no
you're not sure". Please correct me if that's wrong.

I'm still trying to understand what an "aversion tactic" might be. A
tactic that somehow causes you to look in another direction? It just
doesn't seem coherent - and it certainly isn't applicable to the
situation where you used it, because if I was looking in another
direction, I wouldn't have seen the question, and wouldn't have
responded to it.

Can you give another example where the phrase has been used.
Something published on the web would obviously be easier to examine
context.

*In what way
is giving an answer that your are almost certain is wrong useful? *

I could have been almost certain I was correct,

Were you almost certain the number I was thinking of was 5?
If so, why (and how)?
It seems extremely unlikely.

regards, Ian SMith
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On Thu, 1 Sep 2005 13:51:32 -0500, Duffle wrote:

Indeed, those are two situations that a helmet would certainly not help
in. But you make a mistake by saying that steveyo would probably not
have this accident again. Clearly, that's true.

I made a mistake in saying something that's clearly true?
I think you'll need to explain that to me more slowly.

But what if before, his
accident, he had this accident but without a helmet. This is a
hypothetical situation, just as the ones you presented. But could still
happen. You obviously can't know exactly how this would have happened.
But say that steveyo had just read this thread, but about a different
person, and listened to you. Admittedly, you claim that you are not
saying that a helmet is useless, which I can accept. However, it comes
across strongly as if you are saying that. So steveyo goes out with his
new knowledge that helmets are "useless" and then falls, with enough
force to compress the foam on a helmet, and crack it, and this happens
to his head. What does that mean?

I have very little idea what it means.

It seems to be "what if something that didn't happen did happen in the
past, but not like it did happen and something else occurred as a
consequence of me saying something you accept is true but someone else
might not understand and as a consequence of that broke the helmet he
wasn't wearing when it didn't happen". Is that it?

regards, Ian SMith
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Hi - remember me, the OP.

I'd like to officially close this thread.

Take it over to "Just Conversation" or something.

Sheesh.


--
steveyo - Last will be first

steveyo

"I complained I need new shoes, until I met a man with no feet." -
unknown

"Do whatever steps you want if
you have cleared them with the pontiff"- Tom Lehrer


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steveyo wrote:
*Hi - remember me, the OP.

I'd like to officially close this thread.

Take it over to "Just Conversation" or something.

Sheesh. *

Unfortunately Ian Smith and some others read and post RSU via a
newsreader so would not see a thread in ‘just conversation’. I think I
understand what your getting at but some of the posts do bring a smile
or two.

Oh and here’s something I doubt Ian will like

http://tinyurl.com/a4q8a

And I’m not getting into this debate but I am reading it.


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steveyo wrote:
*Sheesh. *
I second the sheesh. I'm trying to think of ways this community can do
something to help the hurricane victims (whether they were wearing
helmets or not).


--
johnfoss - More Moab Fun

John Foss, the Uni-Cyclone
"jfoss" at "unicycling.com" -- www.unicycling.com

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