Helmet design flaw may put cyclists at risk

[James Annan]

Richard wrote:

> James Annan wrote:
>
>> A certain medical test gives a negative result for 90% of healthy
>> patients (positive for the other 10%), and a positive test for 90% of
>> ill patients (neg for the other 10%).
>>
>> Someone takes the test, and the result is positive. What is the
>> probability that he suffers from the disease?
>
>
> You can't tell based on those numbers. You also need to know the
> proportion of the population who actually have the disease in question.
>
>> I've heard that doctors frequently get this wrong, BTW.
>
>
> Well, I'm a doctor, and...oh, you mean /that/ sort. I have bad
> handwriting, does that count?
>


Oh, and I should mention that doctors get it wrong even when given
adequate information to answer the question! But I wanted to leave out
the crucial info in order to find out if anyone thought that the
question was well-posed as stated.

James
--
James Annan
see web pages for email
http://www.ne.jp/asahi/julesandjames/home/
http://julesandjames.blogspot.com/

 

[John_Kane]

Tony Raven wrote:
> Tony Raven wrote:
> >> Its a 2003 NS article and the paper, for those with Science Direct
> >> access is at http://dx.doi.org/10.1016/S0001-4575(03)00062-9
> >>
> >
> > An interesting excerpt:
> >
> > "The wearing of a bicycle helmet was documented in only three victims.
> > All three had a combination of severe injuries: skull fractures,
> > subdural haematoma, subarachnoid haemorrhage, contusions and brain
> > swelling in all three, an intracerebral haematoma in one and an
> > extradural haematoma in one. All three patients died. Their ages were
> > 50, 65 and 71. In one patient, a bystander reported that the helmet had
> > shifted backwards at the moment of the impact on the forehead."
> >
>
>
> Must stop replying to my own posts but having searched the paper I've
> finally found the sentence that for 83 individuals studied "Mortality
> was 33.3%". Which means statistically you would have expected two of
> the three helmeted cyclists to have survived whereas all three died. So
> what's the probability that it was chance that all three rather than one
> died?

I never could remember basic probabilities However I think you
might have to allow for age as well. The helmeted fatalites were all in
the higher age brackets with a concommitent poorer prognosis if I read
the paper correctly.

Is there a biostatistician in the house ?

John Kane, Kingston ON Canada

 

[Dave Kahn]

John_Kane wrote:

> Actully though I think the Tower of London has some possible protective
> gear that should be considered. That suit of armour of Henry VIII
> looked like a possiblity

It would make hill climbing a bit of a chore though.

--
Dave...

 

[Richard]

Dave Kahn wrote:
> John_Kane wrote:
>
>> Actully though I think the Tower of London has some possible protective
>> gear that should be considered. That suit of armour of Henry VIII
>> looked like a possiblity
>
>
> It would make hill climbing a bit of a chore though.

ITYM "challenge" ;-)

R.

 

[Tony Raven]

John_Kane wrote:
>
> Actully though I think the Tower of London has some possible protective
> gear that should be considered. That suit of armour of Henry VIII
> looked like a possiblity

You could have something there. If we were to put a metal protective
case round the cyclist.....it would probably need an extra wheel at each
corner to make the weight stable and a small motor to help cope with the
extra weight....... It could catch on! Have to be careful about risk
compensation though.

--
Tony

"The best way I know of to win an argument is to start by being in the
right."
- Lord Hailsham