Fun with math
From an article in the Tri-State (Raleigh, N.C.) (Pennsylvania) Observer comes this, referring to the use of cameras at traffic lights:
From Garland, Tex., to New York City, the number of cameras is still on the rise, with some 140 communities seeing 40 percent more of them in the past two years. In many places, they’re a popular way to reduce certain kinds of accidents - mostly side-impact or T-bone collisions - and discourage red-light runners, particularly on packed urban crossroads. More than 300,000 red-light violations were issued in New York in 2003, and traffic deaths dropped in the city from 701 in 1990 to 344 13 years later.
The logic is that by adding cameras, New York has reduced red-light runners.
But it’s bad logic. There are a lot of factors that could have (and likely did) cause that reduction in accidents: better medical care, safer cars, more and slower traffic, more seat-belt use, etc.
The idea of assigning blame or credit to something when there are a lot of factors — that is, when you ignore a lot of factors — is a political tool. Imagine the sheriff who touts a 25 percent reduction in crime since he took office, but fails to mention a new anti-gun law. (Or vice-versa: Touting the effects of an anti-gun law and ignoring a new, tough sheriff.)
School uniforms are another example; they get the credit for reducing crime and improving grades, but reports of this tend to ignore other factors — hiring more teachers, adding afterschool programs, or whatever.
Have the red-light (or the sheriff or the school uniforms) made a difference? Probably. But implying that they deserve all the credit is, well, bad math.
