[This piece, by John Carr, was originally published by the National Motorists Association]
When complaints grow too loud, reporters ask public safety agencies for reassurance that traffic law enforcement really is all for the best.
Accused of running a speed trap, the sheriff explained his speed enforcement cut fatal accidents from three or four per year to zero. Police said right-angle collisions were down by half at intersections with red light cameras. The Department for Transport proudly reported that road injuries were down 30% since the introduction of speed cameras.
This is all compelling evidence.
This is all lies.
The government has unique access to safety data. We have to go digging for it if we’re allowed to see it at all. Out of the countless lies told by government to justify regulations or enforcement, these three are among the very few that were independently fact checked.
Aren Cambre pulled the accident reports for Westlake, Texas and discovered that fatal accidents went up when the Sheriff started his speed trap. There were not 3-4 per year before, there were two in total in the previous six years. There were not zero after, there was an average of one per year. The death rate more than doubled.
An auditor asked Manitoba’s government monopoly insurance provider for claim records for Winnipeg. Accidents near cameras were way up. Serious accidents more than doubled and injuries were up 64%.
A researcher bypassed police statistics and checked hospital records to see how many people had been injured in car accidents. Serious injuries had not decreased, as the government claimed. They had increased. Police cut reported injuries by one third by simply not reporting them.
Both Winnipeg and the British government learned from their mistakes. Next time Winnipeg got accident statistics from the provincial insurer the city refused to release them to the public. We can guess what they say. The Department for Transport tried to suppress a study that showed speed cameras increased accidents in work zones.
Around 1990 the U.S. government sponsored a study on the effect of changing speed limits. When the study confirmed the well known result that numbers on signs do not do much of anything, the National Highway Traffic Safety Administration refused to publish the report. Fortunately, NMA lobbyist Gail Morrison got her hands on a copy and passed it around Congress. The national speed limit was repealed soon after.
We call it cherry-picking. You pick and polish the evidence that supports you and try to bury the rest where nobody will find it.
When you see a statistic, ask yourself: is it the truth, the whole truth, and nothing but the truth? Do I believe what they are telling me? Can I figure out what are they not telling me?
I’ll come back to this later. In the meantime, a puzzle:
I don’t care about reducing red light running or red light running crashes. Why not?
A clue: read about “proxy variables” in statistics.
[Courtesy: The National Motorists Association]