H*lmets again - new study - sorry

[Zog The Undeniable]

Guy, can you provide an eloquent rebuttal for this one? It was posted
to r.b.t and I note the researchers have dragged up the discredited 85%
figure again.

http://economics.uta.edu/grant/helmet.pdf

 

[Tony Raven]

Zog The Undeniable wrote:
> Guy, can you provide an eloquent rebuttal for this one? It was posted
> to r.b.t and I note the researchers have dragged up the discredited 85%
> figure again.
>
> http://economics.uta.edu/grant/helmet.pdf

Having read through briefly they appear to make a fairly standard mistake.
They count head injuries in juveniles compared to adults and pedestrians
across the introduction of a state helmet law. They find head injuries
decline in the juvenile population and ascribe this to the helmet law. In a
sense they are correct - the helmet law has caused a reduction in head
injuries in juveniles. However they have not examined the causal link. The
usual reason the head injuries decline is because it puts juveniles off
cycling so less cyclists, less head injuries. The only discussion they make
of this is to factor out long term trends in cycling levels (while ignoring
the step change the laws create) and to comment there was no evidence of cycle
journeys being substituted by car or pedestrian journeys. When the fewer
cyclists has been factored in, most studies find that the decline in cyclist
numbers was greater than the decline in head injuries i.e the risk of head
injury for those that still cycled went up. The authors make the mistake here
of ignoring this crucial effect instead trying mistakenly to ascribe the
change in head injuries to the protective effect of the helmet. The most
effective way though to stop all cyclist head injuries is to stop people
cycling and these helmets laws go some way along the way to achieveing that.

Tony

 

[Just zis Guy, you know?]

On Wed, 16 Jun 2004 18:52:04 +0100, Zog The Undeniable
<[email protected]> wrote in message <40d08a14.0@entanet>:

>http://economics.uta.edu/grant/helmet.pdf

Looks like another meta-analysis based on the same fallacies (e.g. not
adjusting for exposure, as Tony says). I'll look into it in more
detail. The authors have no particular history and of the
acknowledgees I don't know of any save The Safe Kids Campaign, which
is funded by Bell.

It sounds implausible, since in the USA as a whole helmet use has
risen from 18% to 50%, and in the same period the injury rate has
risen by 40%.

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

 

[mark]

"Tony Raven" wrote ...
> Zog The Undeniable wrote:
> > Guy, can you provide an eloquent rebuttal for this one? It was posted
> > to r.b.t and I note the researchers have dragged up the discredited 85%
> > figure again.
> >
> > http://economics.uta.edu/grant/helmet.pdf
>
> Having read through briefly they appear to make a fairly standard mistake.
> They count head injuries in juveniles compared to adults and pedestrians
> across the introduction of a state helmet law. They find head injuries
> decline in the juvenile population and ascribe this to the helmet law. In
a
> sense they are correct - the helmet law has caused a reduction in head
> injuries in juveniles. However they have not examined the causal link.
The
> usual reason the head injuries decline is because it puts juveniles off
> cycling so less cyclists, less head injuries. The only discussion they
make
> of this is to factor out long term trends in cycling levels (while
ignoring
> the step change the laws create) and to comment there was no evidence of
cycle
> journeys being substituted by car or pedestrian journeys. When the fewer
> cyclists has been factored in, most studies find that the decline in
cyclist
> numbers was greater than the decline in head injuries i.e the risk of
head
> injury for those that still cycled went up. The authors make the mistake
here
> of ignoring this crucial effect instead trying mistakenly to ascribe the
> change in head injuries to the protective effect of the helmet. The most
> effective way though to stop all cyclist head injuries is to stop people
> cycling and these helmets laws go some way along the way to achieveing
that.
>
> Tony
>
>
One of the footnotes in the study mentions a 12% reduction in fatalities and
a 20% reduction in bicycle usage in the 1990's. The authors sem to have
conveniently ignored their own footnote in making their claims.
--
mark

 

[Just zis Guy, you know?]

mark wrote:

> One of the footnotes in the study mentions a 12% reduction in
> fatalities and a 20% reduction in bicycle usage in the 1990's. The
> authors sem to have conveniently ignored their own footnote in making
> their claims.

They also seem to have ignored the pre-existing trends and the very similar
trend among child pedestrians. Maybe they are using Cook & Sheikh helmets?

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

 

[Brendan Halpin]

Zog The Undeniable <[email protected]> writes:

> Guy, can you provide an eloquent rebuttal for this one? It was
> posted to r.b.t and I note the researchers have dragged up the
> discredited 85% figure again.
>
> http://economics.uta.edu/grant/helmet.pdf

It's a quite sophisticated paper from a statistical point of view,
strongly based in economics. You can also see that the authors have
thought pretty hard about the issue (sensible comments about risk
compensation, etc.). The big weakness of the cost-benefit analysis
is that they completely ignore the value of forgone cycling (and
its mid- and long-term health consequences). Their only basis for
doing this is that there is no significant effect of child-helmet
laws on miles driven. As remarked, footnote 6 shows they are aware
of the declining trend. It's a remarkably weak test for a
cycling-reduction effect, if one considers the number of
person-miles cycled by children, and the small proportion of that
which is "necessary" transport rather than play, in comparison with
the huge number of miles driven (it's all they have in the dataset,
but it is far too weak to depend on).

It's a good economics paper, which means its conclusions are as
good as its assumptions. Ignoring the level of child-cycling clouds
the conclusion, but it is still correct: helmet laws reduce
fatalities partly (perhaps primarily) by reducing cycling. If I
were refereeing this for a journal, I would simply ask for this to
be acknowledged centrally in the discussion (and for them to drop
the 85% claim -- how can they not contest this when they come up
with 15% in their own research???).

Brendan
--
Brendan Halpin, Department of Sociology, University of Limerick, Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-390476; Room F2-025 x 3147
mailto:[email protected] http://www.ul.ie/sociology/brendan.halpin.html

 

[Simon Brooke]

in message <[email protected]>, Just zis Guy, you know?
('[email protected]') wrote:

> trend among child pedestrians. Maybe they are using Cook & Sheikh
> helmets?

I thought it was Sheikh and Bake?

Incidentally seeing it's Edinburgh and child health, is the Cook Robin's
ex-wife?

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
Just as defying the law of gravity through building aircraft requires
careful design and a lot of effort, so too does defying laws of
economics. It seems to be a deeply ingrained aspect of humanity to
forever strive to improve things, so unquestioning acceptance of a
free market system seems to me to be unnatural. ;; Charles Bryant

 

[Just zis Guy, you know?]

Simon Brooke wrote:

>> Maybe they are using Cook & Sheikh helmets?
> I thought it was Sheikh and Bake?

Or is it Sheikh and Vac[uous]?

> Incidentally seeing it's Edinburgh and child health, is the Cook
> Robin's ex-wife?

No idea - I guess not or someone would surely have mentioned it before.

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

 

[David Martin]

On 17/6/04 10:35 pm, in article
[email protected], "Simon Brooke"
<[email protected]> wrote:

> Incidentally seeing it's Edinburgh and child health, is the Cook Robin's
> ex-wife?

Seeing as his name is adrian and he works in London, probably not.

...d