On 22 May 2010 12:00, John Francis <jo...@panix.com> wrote:
>
> Such studies have been done, of course. But all they can measure is the
> accident rate in the jurisdiction; they can't compare the accident rate
> with helmets to the rate for the same area without helmet use.
>
But they can.
Studies from a period before mandatory helmet wearing can be compared
to a period immediately after helmet mandation. Provided other
factors haven't significantly changed, and the study periods encompass
the same cycling population in the same place and in the same seasons,
then the results can be fairly compared.
regards, Anthony
"Of what use is lens and light
to those who lack in mind and sight"
(Anon)
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