2/28/2013UK: Complaint Lodged Against Dodgy Speed Camera Statistics
UK Advertising Standards Authority investigating claims of speed camera efficacy.
Do advertisements touting the benefits of speed cameras meet the legal definition of false advertising? The Alliance of British Drivers (ABD) thinks so. Malcolm Heymer, a retired civil engineer with thirty years of experience who advises the group, filed a complaint last week with the UK Advertising Standards Authority, an independent agency that enforces UK laws against false advertising.
Heymer took aim at ads that appeared in Local Transport Today paid for by Vysionics Intelligent Traffic Solutions, a vendor of automated ticketing machines. The advertisements claimed that the point-to-point, average speed camera system known as SPECS was responsible for a reduction in the worst sort of traffic collisions of over 70 percent.
"The clear implication of this wording is that it is the SPECS installations alone that are responsible for what appears to be, at face value, an impressive reduction in KSI (killed and seriously injured) casualties. The claim deliberately ignores other universally recognized factors that make significant contributions to casualty reductions at speed camera sites," Heymer wrote. "It is clear that Vysionics' claim is intended to convince potential clients that buying one of its systems will reduce road casualties substantially, and in my view this amounts to fraudulent misrepresentation."
A Vysionics press release from 2011 listed fifteen photo enforced locations where the claimed casualty reduction was a combined 73 percent. Heymer noted Department for Transport statistics show exceeding the speed limit was a factor in 7 percent of fatal and serious injury accidents. From this, he argued the maximum possible KSI accident reduction from full compliance with the posted speed limit would be 7 percent. He insists the camera company has inflated its claim by relying on tricks, including a statistical phenomenon known as regression to the mean.
"In almost all cases, speed cameras (of whatever type) are installed following a period during which accident numbers at a location or along a length of road have been higher than usual," Heymer wrote. "So there is a high probability that the numbers would fall again anyway, without intervention. That accident numbers dropped after the camera was installed very often has nothing to do with the camera being there, but the camera gets the credit for the fall in casualties."
The official accident figures from thirteen of the fifteen locations selected by Vysionics reveal additional flaws in the claim. At A46 Farndon, A616 Stocksbridge Bypass, A228 Isle of Grain, A6514 Ring Road - Nottingham and A52 Bingham, Vysionics overstated the accident reduction. At A52 Bingham, accidents ranged between zero and three incidents per year, which are numbers far too low to discern any statistically significant trend.
"In only one case does it appear that the SPECS system may have had a real effect on KSI numbers, although there is a possibility that other, unknown factors may have played a part in the observed casualty reduction," Heymer wrote. "In conclusion, the claim that 'SPECS installations on average reduce KSIs by greater than 70 percent' is clearly not supported by an analysis of the evidence. Vysionics should therefore be told to retract its claim and not to repeat it or similar claims in the future."
The Advertising Standards Authority has acknowledged the complaint and is looking into it. The agency has ruled against misleading speed camera statistics in the past. In 2006, the agency chastised Greater Manchester police for producing a booklet that relied on misleading camera statistics. In 2005, the agency ruled against the West Yorkshire speed camera partnership. A related agency, the UK Statistics Commission, condemned the national government's speed camera claims in 2006 based on the findings of the British Medical Journal.