This is a shockingly bad paper and one has to ask how on
earth it got through the referees. (BMJ 2005;330:331-4).
It is an uncritical non-metaanalysis which they claim to
be systematic of 14 observational studies. The best paper
is type 3 evidence, most are worse.
"In terms of methodological quality, we classified no
studies as being good quality, 7 as average, 2 as
average-poor and 5 as poor."
Papers quoted include, "Traffic Speed Cameras prove to be
lifesavers" from Law and Order in 1996.
None of the papers as far as I can see has looked at the
changes on road deaths in the last 5 years where the trend
is pretty well static between 1992 and 2002, and actually
rising in some groups such as motorcyclists and their
passengers, as well as car drivers and occupants,
although less dramatically, since 1998.
http://www.statistics.gov.uk/STATBASE/ssdataset.asp?vlnk=4
031
Nowhere are there actuarial figures showing what is
happening to collisions in countries where cameras have
been introduced. Surely this is available from insurers?
The BMJ compound the error by plastering the front cover
with "Effectiveness of speed cameras. They reduce crashes
and related casualties." The paper does not prove either
of these assertions.
We would all like to see fewer casualties and collisions.
A paper like this does nothing to improve the debate and
has, in my view badly damaged the BMJ's independence and
credibility.
/Rowley./
|