Helmet propaganda debunked

On Tue, 10 May 2005 05:42:39 GMT, (Bill Z.)
wrote:

Sigh. As I said, population-based studies of fatality rates are
by and large useless for assessing helmet effectiveness because
the number of fatalities per year is too low to determine anything
about the helmets - the statistical error is too high.

I have always wondered why you consider studies based on entire
populations to be less reliable than those based on a few hundred,
often self-selected individuals.

But be that as it may, in case anyone is not aware, there is a debate
raging in the medical community at present about observational studies
(almost all pro-helmet studies are of this type). This follows on
from some very public failures of such studies, such as the link
between hormone replacement therapy and coronary heart disease in
women, where numerous observational studies got both the magnitude and
the sign of the relationship wrong.

Current thinking is that unless there is strong evidence from other,
different types of studies, observational studies should not be
treated as reliable. For an interesting overview see "Hormone
replacement therapy and coronary heart disease", Pettiti D,
International Journal of Epidemiology, 2004;33:461-463 and "The
hormone replacement - coronary heart disease conundrum: is this the
death of observational epidemiology?" Lawlor DA, Smith GD & Ebrahim S,
International Journal of Epidemiology, 2004;33:464-467

Confounding between the chooser and the choice (documented in all
observational helmet studies) led researchers to come to a consensus
which, in this case, turned out to be entirely wrong. They had a
plausible mechanism to explain the correlation, numerous studies found
the same thing, there were meta-analyses and literature reviews which
provided endless support for the hypothesis - but it was still wrong.

In this case we know it was wrong because they could conduct clinical
trials, which is unethical in the case of helmets.

Pettiti draws four useful lessons from this:

* Do not turn a blind eye to contradiction
Do not ignore contradictory evidence, and especially do not
repudiate it, but try instead to understand the reasons behind the
contradictions.

* Do not be seduced by mechanism
Even where a plausible mechanism exists, do not assume that we know
everything about that mechanism and how it might interact with other
factors.

* Suspend belief
"belief caused [researchers] to be unstrenuous in considering
confounding as an explanation for the studies".

* Maintain scepticism
Good science lies in trying to disprove, not prove, your hypothesis.

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 CHS, Puget Sound

Just zis Guy, you know? wrote:

I have read the AAP paper, by the way, if you want to discuss it in
detail. I think Frank has as well.

Of course.

- Frank Krygowski

Bill Z. wrote:
writes:


You should make your position more clear, Bill. Are you really
saying
fatality data is _important_ for assessing helmet effectiveness,
but
not _useful_ for assessing helmet effectiveness?

Sigh. As I said, population-based studies of fatality rates are
by and large useless for assessing helmet effectiveness because
the number of fatalities per year is too low to determine anything
about the helmets - the statistical error is too high.

IOW, bike fatalities are vanishingly rare - which is true. Weirdly,
helmet proponents still use the fear of such fatalities to argue for
helmets, and in this forum, they use the assumption that cycling is
dangerous to mock anyone who disagrees. (Ever read the words "organ
donor" here?)

That doesn't mean that "fatality data is unimportant." It tells
you something about the extent of whatever safety problem you have.
Is that *really* so hard for you to understand?

I understand that. What I don't understand is how you manage to
simultaneously think "There's hardly any safety problem in cycling" and
"But if you don't promote helmets, you're a __________" [insert any one
of Zaumen's insults]


Rather, you are reflexively playing dumb as usual. I've yet to see
one honest discussion by you in well over a decade. Everything you
post is mostly spin and distortions of one kind or another.

Ah well. I'll just say that many others disagree.

---------------------------------------------------------------------
Cycling is NOT very dangerous. It does us no good to pretend it is.

See http://www.bicyclinglife.com/SafetyS...SafetyQuiz.htm

- Frank Krygowski

"Bill Z." wrote in message
...
"Riley Geary" writes:

"Bill Z." wrote in message
....
The mandatory helmet law in California applies to children and
younger teenagers, most of whom avoid streets with heavy traffic.

Just to set the record straight, the CA MHL actually applies to every
bicyclist under the age of 18.

18 and 19 year olds are still in their teens, last I heard.

Sure, but do you really believe 16 and 17 year-olds qualify as "younger"
teenagers? I think most people would agree that such a term properly
applies to 13 and 14 year-olds, and depending on the context, perhaps to 15
year-olds as well; but I doubt they would consider 16 and 17 year-olds
should be covered by such a term, even if they are obviously younger than 18
and 19 year-olds.

Likewise, according to the accident stats, 16 and 17 year-old cyclist
crashes much more closely resemble the crash types adult cyclists tend to
get into rather than the crash types younger cyclists are more typically
involved with, including a greater affinity for streets and highways with
higher speed limits and/or heavier traffic.

And the point was that we have a fairly low age limit -

Low compared to what--places like Australia, New Zealand, and British
Columbia that have universal MHL's covering all bicyclists, regardless of
age? California's age limit is certainly not low when compared to any of
the other 19 US states that have enacted MHL's for juvenile cyclists, almost
all of which specify a cutoff age of 16 or lower as I pointed out before.
Indeed, as I keep pointing out, California's MHL is the very broadest of all
such statewide laws currently in the US.

Riley Geary

"Riley Geary" writes:

"Bill Z." wrote in message
...
"Riley Geary" writes:

"Bill Z." wrote in message
...
The mandatory helmet law in California applies to children and
younger teenagers, most of whom avoid streets with heavy traffic.

Just to set the record straight, the CA MHL actually applies to every
bicyclist under the age of 18.

18 and 19 year olds are still in their teens, last I heard.

Sure, but do you really believe 16 and 17 year-olds qualify as "younger"
teenagers? I think most people would agree that such a term properly
applies to 13 and 14 year-olds, and depending on the context, perhaps to 15
year-olds as well; but I doubt they would consider 16 and 17 year-olds
should be covered by such a term, even if they are obviously younger than 18
and 19 year-olds.

You guys are quibbling. The fact is that this law doesn't apply to all
teenagers, much less adults, and that is inconsistent with the hypothesis
Tom suggested - that the mandatory helmet laws are there to make drivers
more comfortable.


And the point was that we have a fairly low age limit -

Low compared to what--places like Australia, New Zealand, and British
Columbia that have universal MHL's covering all bicyclists, regardless of
age?

Low compared to the age of most people commuting to work, where they
are more likely to have to ride on streets with significant traffic
than the kiddies are. Read Tom's posts to see the context.



--
My real name backwards: nemuaZ lliB

"Just zis Guy, you know?" writes:

On Tue, 10 May 2005 05:42:39 GMT, (Bill Z.)
wrote:

Sigh. As I said, population-based studies of fatality rates are
by and large useless for assessing helmet effectiveness because
the number of fatalities per year is too low to determine anything
about the helmets - the statistical error is too high.

I have always wondered why you consider studies based on entire
populations to be less reliable than those based on a few hundred,
often self-selected individuals.

I've always wondered why you can't read simple English. I said
"population-based studies of fatality rates", and your "entire
populations" generally refer to countries with tiny populations
(in some cases smaller than the Bay Area). Furthermore, I never
said that I trusted studies based on a few hundred individuals.
You simply made that up.

I'll snip the rest of your posts today. Try again tomorrow if
you can manage to hold a discussion at a reasonable level. I've
better things to do than to argue with someone who continually
misrepresents what I post.

rest of garbage snipped - he's ranting again and cutting and pasting
--
My real name backwards: nemuaZ lliB

writes:

Bill Z. wrote:
writes:


You should make your position more clear, Bill. Are you really
saying
fatality data is _important_ for assessing helmet effectiveness,
but
not _useful_ for assessing helmet effectiveness?

Sigh. As I said, population-based studies of fatality rates are
by and large useless for assessing helmet effectiveness because
the number of fatalities per year is too low to determine anything
about the helmets - the statistical error is too high.

IOW, bike fatalities are vanishingly rare - which is true. Weirdly,
helmet proponents still use the fear of such fatalities to argue for
helmets, and in this forum, they use the assumption that cycling is
dangerous to mock anyone who disagrees. (Ever read the words "organ
donor" here?)

A few random people occassionally using colorful language while making
off-the-cuff remarks are not "helmet proponents."

That doesn't mean that "fatality data is unimportant." It tells
you something about the extent of whatever safety problem you have.
Is that *really* so hard for you to understand?

I understand that. What I don't understand is how you manage to
simultaneously think "There's hardly any safety problem in cycling" and
"But if you don't promote helmets, you're a __________" [insert any one
of Zaumen's insults]

Produce one post in the last 10 years or longer where I ever called
anyone anything for not promoting helmets or be branded the liar that
you are. You must really be desparate to make this sort of thing up.

For that matter you won't be able to find one single post where I ever
told anyone to use a helmet. And if you don't want "insults" from me,
you might consider that people who live in glass houses shouldn't
thow stones. Whatever "insults" I've posted are pretty mild
compared to the abuse you characters heap on everyone who disagrees
with you.

Rather, you are reflexively playing dumb as usual. I've yet to see
one honest discussion by you in well over a decade. Everything you
post is mostly spin and distortions of one kind or another.

Ah well. I'll just say that many others disagree.

I doubt that (excluding Guy and a few of your friends who also play
dumb.)


--
My real name backwards: nemuaZ lliB

Bill Z. wrote:
writes:
What I don't understand is how you manage to
simultaneously think "There's hardly any safety problem in cycling"
and
"But if you don't promote helmets, you're a __________" [insert any
one
of Zaumen's insults]

Produce one post in the last 10 years or longer where I ever called
anyone anything for not promoting helmets or be branded the liar that
you are. You must really be desparate to make this sort of thing up.

For that matter you won't be able to find one single post where I
ever
told anyone to use a helmet. And if you don't want "insults" from
me,
you might consider that people who live in glass houses shouldn't
thow stones. Whatever "insults" I've posted are pretty mild...

:-) OK, I stand corrected. Nothing you have ever posted has ever
given the slightest hint that you're in favor of helmet promotion.
Also, your insults have always been very mild, very reasonable, and
applied only reluctantly to people who obviously deserved them.

Can I turn the sarcasm off now? ;-)

- Frank Krygowski

writes:

Bill Z. wrote:
writes:
What I don't understand is how you manage to
simultaneously think "There's hardly any safety problem in cycling"
and
"But if you don't promote helmets, you're a __________" [insert any
one
of Zaumen's insults]

Produce one post in the last 10 years or longer where I ever called
anyone anything for not promoting helmets or be branded the liar that
you are. You must really be desparate to make this sort of thing up.

For that matter you won't be able to find one single post where I
ever
told anyone to use a helmet. And if you don't want "insults" from
me,
you might consider that people who live in glass houses shouldn't
thow stones. Whatever "insults" I've posted are pretty mild...

:-) OK, I stand corrected. Nothing you have ever posted has ever
given the slightest hint that you're in favor of helmet promotion.
Also, your insults have always been very mild, very reasonable, and
applied only reluctantly to people who obviously deserved them.

Can I turn the sarcasm off now? ;-)

You lied through your teeth, Kyrgowski, and won't realy apologize
for it (hence your last sentence.) As I said, produce the URL
or be branded the liar that you are.


--
My real name backwards: nemuaZ lliB

On Wed, 11 May 2005 01:47:36 GMT, (Bill Z.)
wrote:

Sigh. As I said, population-based studies of fatality rates are
by and large useless for assessing helmet effectiveness because
the number of fatalities per year is too low to determine anything
about the helmets - the statistical error is too high.

I have always wondered why you consider studies based on entire
populations to be less reliable than those based on a few hundred,
often self-selected individuals.

I've always wondered why you can't read simple English. I said
"population-based studies of fatality rates", and your "entire
populations" generally refer to countries with tiny populations
(in some cases smaller than the Bay Area).

So you say. But the entire case for helmets is founded on studies
several orders of magnitude smaller than that. So, if the population
of New Zealand is not a big enough sample size (incidentally, serious
injuries are counted as well as fatalities) then it's for certain sure
that under 300 people in Seattle, Washington is not a reliable sample
either.

Furthermore, I never
said that I trusted studies based on a few hundred individuals.
You simply made that up.

OK, so which studies do you trust? Cite them.

The only study of which I'm aware which meets your one stated
criterion (more cases than the population of the Bay Area) is Rodgers
(1988), which concludes that bicycle construction standards have a
greater impact on cyclist safety than helmets. It includes the
following: "There is no statistical evidence that the growth of
hard-shell helmets has reduced head injuries or deaths. In fact [...]
fatalities are positively and significantly associated with increased
helmet use".

The widely-publicised failure of observational studies in predicting
the link between coronary heart disease and HRT (where the magnitude
and sign of the predicted relationship were wrong), along with other
recent high-profile failures, means that observational studies cannot
be taken as reliable unless they are backed up by evidence form
different kinds of study.

In this case the observational studies predicted anything between 60%
and 85% head injury reduction, some even going so far as to claim
greater efficacy against the most serious injuries, but when usage in
the population rose, in some cases more than doubling in a single
year, no benefit was discernible. Our road safety minister concluded
that there is no known case where cyclist safety has improved as a
result of increasing helmet use. And yet, according to you, the only
studies which are believable are the tiny ones, using a methodology
which is now proven to produce completely the wrong result at least
some of the time, conducted almost without exception by people who
have made up their minds beforehand.

I'll snip the rest of your posts today.

Translation: "Tra la la la la, I'm not listening". As ever.

Try again tomorrow if
you can manage to hold a discussion at a reasonable level.

Your definition of reasonable excludes disagreeing with you. Fallacy
of exclusion.

I've
better things to do than to argue with someone who continually
misrepresents what I post.

Interesting. You are prepared to take time to trade insults with me,
but not to actually read what I post. You seem determined to take
absolutely everything personally, and in this thread especially you
have avoided any discussion of the real issues. And yet you are
accusing everyone else of various infractions. Sounds like you are
just trolling to me.

rest of garbage snipped - he's ranting again and cutting and pasting

And here is the space for you to cite the text which was sufficiently
immoderate to be characterised as a rant:




And here is the space for you to identify which lines were copied &
pasted, complete with the posting reference from which you suggest
they were taken; bonus point if you can show that you have addressed
any of the alleged copied & pasted text already:



Put up or shut up.

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 CHS, Puget Sound