Actually, the report undermined itself, albeit in a very underhand way... The "proper research" was detailed on about page 157 (Appendix "H") of the report. Buried quietly amongst the small print was the admission that the headline 42% figure quoted in the Executive Summary - and thus picked up by most idle journalists - was the "raw" figure which needed to be adjusted in order to be realistic. The adjustments that were made were for "trend" and "Regression To The Mean" (Ian's "rubber chicken theory"). Trend was considered to account for 1-5th of the total effect and RTTM for no less than 3-5ths, so the cameras themselves were, at best, responsible for 1-5th of 42% = 8%. Owing to the small sample size at each site, 8% is not statistically significant, therefore there's no evidence that cameras do anything at all.
So, claiming that cameras give a 42% reduction means that a rubber chicken would make at least a 34% reduction - and cost a lot less than a Gatso.
-- Jeff. Ironbridge, Shrops, U.K. and don't bother with ralf4, it's a spamtrap and I never go there.. :)
... "There are few hours in life more agreeable than the hour dedicated to the ceremony known as afternoon tea.."
Henry James, (1843 - 1916).
