Ontario Helmet Law being pushed through

On Sat, 11 Dec 2004 19:42:30 GMT, (Bill Z.)
wrote:

He is trying to deliberately mislead readers to bolster his argument.
You can speculate about any additional motivation(s) he may have.
Using phrases like "whole country" in comparison to a study using "a
single metropolitan area" is highly misleading if people don't know
that the "whole country" is actually the smaller of the two.

Although Bill is avoiding the issue that pro-helmet studies usually
include a few hundred cases, in exceptional cases a few thousand,
whereas the studies showing no benefit routinely include millions of
cyclists.

What he's doing is morphing a null result due to a small sample size
into a claim that is essentially "helmets are not effective."

LOL! The 1989 Seattle study, far and away the most influential helmet
study ever, studied 235 cases if memory serves, and the total number
of cyclists included, with the population control, was well under a
thousand. Rodgers' study, finding no benefit and slightly elevated
probability of fatality for helmeted riders, covered eight MILLION
cyclist injuries over fifteen years. The New Zealand and Australian
experience covers whole populations - again, MILLIONS of cyclists.

What is the level
of helmet effectiveness that his studies claiming a null result could
have detected given the sample sizes and all other relevant factors?

Anything above about 10% should be visible above the noise as a trend
over and above that for the general population. Efficacy of the order
of 2/3 or more, as claimed by just about every hospital based study,
could not be invisible at the population level, especially against the
context of the very steep rises in helmet use over very short times
shown in New Zealand and Australia.

If you say, "Study X shows that helmets cannot prevent N% of skull
fractures (you may replace "skull fractures with the injury type of
your choice) with a confidence level of Y," and assuming you get Y
correct, that at least is a meaningful statement.

Except we are not the ones selling something. Helmet promoters are
selling, and we, the sceptical public, are entitled to challenge them
to prove their claims. You will note that helmet manufacturers do not
repeat the extravagant claims made by the likes of the SafeKids
campaign. So the real situation is: they say helmets prevent X% of
injuries with confidence interval Y, where Y is admittedly usually
pretty wide due to small sample sizes, and then we look at population
figures and see that they fall well below the minimum predicted.
Which gives the strong impression that the prediction is wrong. Just
as it was in the link between CHD and HRT, but in that case it was at
least ethical to run clinical trials.

After all, what most of us would want to know is simply what fraction
of injuries of a particular type and severity can we expect helmets
to prevent or at least mitigate. We also might want to know if the
cost of the helmet would be paid for by reduced medical bills given
the type of riding we do.

And that data is available from the work done in Australia and New
Zealand: in both cases, helmets failed cost-benefit analysis, for the
simple reason that the kinds of injuries they are designed to prevent
are neither serious nor expensive to treat.

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

On Sat, 11 Dec 2004 19:49:38 GMT, (Bill Z.)
wrote:

Using phrases like "whole country" gives
readers an impression that this is the one with the largest sample
size (and you'll note that in the last message Frank didn't mention it
was New Zealand.) A "null result" can simply mean that your sample is
too small to detect anything.

I think most people will appreciate why whole population studies might
be more relevant than sample studies in this case, whatever the
population, but here is some additional data regarding the sample
sizes of some well-known studies:


1989 Seattle study: 235 cases, about 500 controls
TR&T 1990: 212 cases, 319 controls
Spaite, 1991: 284 cases
Jacobson, 1998: 599 cases
Wassermann et. al, 1998: 516 interviewed, of which 4% cases
Dorsch, 1987: 894 interviewed
Thomas, 1994: 102 cases, 278 controls
TR&T, 1996: 3390 cases

Rodgers, 1988: 8,000,000 cases, control was the entire cyclist
population of the USA - found no benefit
Scuffham, 1997: 5805 cases, estimated 2,000,000 controls - found no
benefit

Population of Australia (no benefit): currently 19,000,000

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

Steven M. Scharf wrote:

Erik Freitag wrote:


... "propaganda" and "code phrase" imply that you think Frank is
deliberately trying to mislead us so we won't, what? Wear helmets?


Yes, Frank is deliberately trying to mislead you. Taking statistics and
studies out of context is one thing he is famous for.

Once again, you're making baseless accusations, and you're making them
without any specifics.

If you have some specific accusations, let's have them. If you're going
to vaguely impugn my character and motives, but not give enough
information for me to defend myself - well, you're acting like a coward.

I think it comes
down to the "everyone must do what I do because this validates what I
do." It is not an uncommon form of behavior. You see this sort of thing
a lot on Usenet.

Personally I despise this sort of thing.

:-) Hah!

You _do_ this sort of thing! We saw it recently in rec.bicycles.tech,
where you spent a solid month slamming anyone who used a lighting system
you didn't like! In particular, anyone who disagreed with the
recommendations you made on your own "world's greatest authority"
website had their points posted on your website as "myths."

And of course, if someone pointed out too many of the technical, factual
mistakes in your website, they got killfiled!

If anyone wants a URL on that thread, let me know. I'll provide it.


--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

Bill Z. wrote:
We also might want to know if the
cost of the helmet would be paid for by reduced medical bills given
the type of riding we do.

Argh, give me a break. In the U.S., most people have at least a $25
co-pay for emergency rooms, usually $50.

I'd be extremely surprised if ANYONE, considers the savings in medical
bills when they decide whether or not to wear a helmet.

"Steven M. Scharf" writes:

Bill Z. wrote:
We also might want to know if the
cost of the helmet would be paid for by reduced medical bills given
the type of riding we do.

Argh, give me a break. In the U.S., most people have at least a $25
co-pay for emergency rooms, usually $50.

I was refering to the cost of treatment, not the out-of-pocket cost
for those who can afford insurance.

As normal, I've flushed all of Guy's comments today and have not
bothered to read them after seeing one silly one.

--
My real name backwards: nemuaZ lliB

On Sun, 12 Dec 2004 02:00:49 GMT, (Bill Z.)
wrote in message :

As normal, I've flushed all of Guy's comments today and have not
bothered to read them after seeing one silly one.

Or rather one which rightly accused you of hypocrisy.

Still and all, I never do expect you to engage on matters of substance
- experience indicates that you are much more comfortable dragging a
thread into personal abuse and then complaining about it.

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

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

On Sun, 12 Dec 2004 00:15:19 GMT, "Steven M. Scharf"
wrote in message
. net:

Argh, give me a break. In the U.S., most people have at least a $25
co-pay for emergency rooms, usually $50.
I'd be extremely surprised if ANYONE, considers the savings in medical
bills when they decide whether or not to wear a helmet.

This assumes that every cyclist will have a head injury crash once
every two to twelve years, depending on the cost of the helmet and
allowing for the five year recommended life.

Elsewhere in this thread we have seen estimates for mean time between
crashes of hundreds to thousands of years, which is probably why the
helmet law countries have found that helmets fail cost-benefit
analysis.

The last time I suffered a head injury while cycling was over twenty
years ago, and I was wearing a helmet at the time anyway.

And, in common with many people including those in Ontario unless I'm
much mistaken, ER treatment is free to me anyway.

So your argument is wrong on several levels.

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

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

Baka Dasai wrote:
On Sat, 11 Dec 2004 19:42:30 GMT, Bill Z. said (and I quote):

Using phrases like "whole country" in comparison to a study using "a
single metropolitan area" is highly misleading if people don't know
that the "whole country" is actually the smaller of the two.


Not that it's relevant, but I think New Zealand has a larger
population than San Francisco:

New Zealand: 4,061,300
http://en.wikipedia.org/wiki/New_Zealand

San Francisco: 776,733
http://sanfrancisco.areaconnect.com/statistics.htm

I don't know how much bigger "San Francisco" is if you include the
surrounding areas, but it would have to be 600% bigger to be bigger than
New Zealand. Maybe it is.

It has about 7 million people.

Bill Z. wrote:

I was refering to the cost of treatment, not the out-of-pocket cost
for those who can afford insurance.

The point is, with or without insurance, no one decides to wear a helmet
or not based on how much injury treatment might cost.

Baka Dasai writes:

On Sat, 11 Dec 2004 19:42:30 GMT, Bill Z. said (and I quote):
Using phrases like "whole country" in comparison to a study using "a
single metropolitan area" is highly misleading if people don't know
that the "whole country" is actually the smaller of the two.

Not that it's relevant, but I think New Zealand has a larger
population than San Francisco:

New Zealand: 4,061,300
http://en.wikipedia.org/wiki/New_Zealand

San Francisco: 776,733
http://sanfrancisco.areaconnect.com/statistics.htm

I referred to the Bay Area (the high density suburban area around and
including San Francisco, with a population of about 6 million.) In case
you don't know, San Francisco's land area is about 50 square miles
(it is approximately a square about 7 miles across.)

I don't know how much bigger "San Francisco" is if you include the
surrounding areas, but it would have to be 600% bigger to be bigger than
New Zealand. Maybe it is. It doesn't matter. Any way you look at it,
New Zealand is big enough to be a valid sample.

It is bigger, and New Zealand is not big enough to give you an adequate
sample given that bike accidents are infrequent. You'll note too that
Frank et al. nearly always refer to serious injuries or fatalities.
We get around 800 bicyclist fatalities per year in the U.S. with a
population of nearly 300,000,000.

--
My real name backwards: nemuaZ lliB