On 19/10/17 17:51, Peter Parry wrote:
On Wed, 18 Oct 2017 09:37:51 +0100, TMS320 wrote:
On 17/10/17 14:49, Peter Parry wrote:
On Mon, 16 Oct 2017 22:15:16 +0100, TMS320 wrote:
On 15/10/17 18:35, Peter Parry wrote:
On Fri, 13 Oct 2017 00:28:39 +0100, TMS320

You have to have a common base to allow for the detection of trends.
Looking for impacts per pedestrian mile or impacts per pushbike mile
is going to produce the same result.Why they chose the measurement
they have I do not know - but it seems to be used by many road
transport investigators worldwide.

The French look at it by population... As I said, their figures show no
connection between casualties and vehicle distance, pedestrian or
occupant.

A vehicle/bike/pedestrian is exposed to the risk of an accident
whenever it is on the road. It would be surprising if the likelihood
of an event turned out to be unrelated to the exposure to the risk be
that in terms of miles traveled or hours driving/walking etc.

Yes, for vehicle occupant casualty against vehicle distance or for
pedestrian casualty against distance walked. Not for pedestrian casualty
against vehicle distance! This is what I take issue to.

You can certainly use the overall measure of accidents per million
inhabitants per year to see if large scale policies are having an
overall effect and you could use the same measure for groups within
the whole - what you cannot do is use the measure of accidents per
million inhabitants to compare the relative probability of an accident
across multiple groups. The French appear to use accidents/million
population for overall figures and accidents/million km for
comparative purposes (for example comparing accidents attributed to
foreign drivers against locals). They also use accidents per hour
when looking at relative risks.

In the recent documents I have I see no figure for pedestrian casualties
per vehicle distance. Perhaps I have missed it?

They used to list pedestrian casualties by department but unfortunately
it seems they no longer do so and just lump all road users together.

They also lament the poor quality of data collection "Accidents with
pedal cyclists who were hospitalised are very under estimated in the
national register of accidents particularly as the police and
gendarmerie are not always called to these accidents
especially if no motorist is involved."

Perhaps, but we're not discussing pedal cyclist versus distance cycled.

The death to injury ratio (RAS30018 Reported casualties sheet), removing
the vehicle-distance element, is the only thing that provides us with an
indication of the severity of non-fatal injuries in a collision,

The severity of injury data for more serious injuries at is available
in hospital admission data and has certainly been included is some
studies.

if
a smaller proportion of injuries convert to death, there must be fewer
life threatening injuries in the mix.

Which has no relationship with causation.

We're not discussing causation either. We are discussing the figures.

You emphasise accuracy of injury reporting but make no mention of
accuracy of distance reporting.

All of the data collection concerning cycling accidents is
inaccurate. The main impact is seen in the often poor design of
measures meant to reduce pushbike casualties.

There measures are more likely to be political and nothing to do with data.

Politicians are not noted for their intelligence and their general
mantra is "Don't just stand there - do something" where "something"
can bear no relationship to the problem. They tend to be overly
influenced by shouty lobby groups (who are also rarely interested in
the truth, their mind is made up and they don't want to be confused by
facts). The civil servants who do make up the briefing papers would
dearly like better facts as they generally do like getting the right
answer.

Indeed.