Paul Smith <
[email protected]> wrote in message
news:<
[email protected]>...
> Further to discussions yesterday I have made a draft page and spreadsheet available concerning the
> UK's loss of previous fatal accident trend in 1993.
>
>
http://www.safespeed.org.uk/fatality.html
>
> Comments welcome. (not cross posted)
Your mathematics may be correct (although I dispute the validity of picking arbitrary trend lines
based on the overall change between two arbitrary years; you have not demonstrated that there is a
statistically significant change since 1993; the data points are well-distributed and the chances of
seeing a 'trend' such as the one you identify purely by blind chance are all too present. The onus
is on you to show that the trend is not attributable to lady luck if you wish to use these figures
to support a case for change in public policy).
Any such analysis should anticipate a gradual fall in the year-on-year percentage change since the
eventual outcome of any road safety policy will be to leave us with a residual level of accidents
that reflect human and technical inadequacy (we will never achieve an accident-free road network
while humans drive, walk and cycle). Each new development in road safety may reasonably be expected
to cause a temporary spike in this for a few years as their impact is felt and then, over subsequent
years, the rate of change will fall away as there is no new advance to reduce the figures.
Even if I grant that that the maths is acceptable, the conclusions you draw from it hold no water.
Your assertion that speed cameras and the speed kills policy are the only possible cause is at worst
ridiculous and at best an assertion unsupported by any causal evidence. The statement that it must
be true because it is the only reasonable cause is infantile, and your attempt to hide such a random
leap of illogic within a mass of reasonable-sounding mathematice akin to the defenses of Astrology
that are littered astronomical terms to impress the gullible.
So let me offer you one alternative hypothesis. In 1992 the Ford Escort was first fitted with an
airbag. This happened on a few K reg models (available Autumn 1993) and became more widespread over
subsequent years (
http://www.parkers.co.uk/pricing/used_options/usedoptions.asp?model_id=389).
Airbags became widely available in the Vauxhall Astra in 1993
(
http://www.parkers.co.uk/pricing/used_options/usedoptions.asp?model_id=234). These 2 cars account
for a large percentage of UK sales. This is not the first introduction of airbags into UK cars, but
it is when they became common.
1993 as a year saw a large percentage reduction in the percentage change of fatalities per billion
vehicle miles (roughly 1% compared to .6% in 1991). This reflects the impact of airbags in reducing
the fatalities of drivers. Since then the percentage change of deaths per billion KM has been
dropping away steadily. I put this down to drivers adapting to the presence of airbags, feeling
safer as a result and driving less safely (there are figures below to support this).
Mr. Smith, you are selling snake oil. Smoke and mirrors, smoke and mirrors.
- Richard Waters
Year Bill. deaths death rate percentage change in death vehicle per vehicle rate per mile miles mile
1992 412.1 4,229 10.2615494 -0.837332209 1993 412.2 3,814 9.252610333 -1.008939067 1994 422.6 3,650
8.637008992 -0.615601341 1995 430.9 3,621 8.404082978 -0.232926014 1996 442.5 3,598 8.131073446
-0.273009532 1997 452.5 3,599 7.95359116 -0.177482286 1998 459.2 3,421 7.449912892 -0.503678268 1999
466.0 3,423 7.345272889 -0.104640003 2000 467.7 3,409 7.288860381 -0.056412508 2001 473.7 3,450
7.283090564 -0.005769817
