Here are the opening paragraphs from a Houston Chronicle story.
Was red-light camera study flawed?
One expert cites lack of control group; city plans for more research
By BRADLEY OLSON
Copyright 2009 Houston Chronicle
Dec. 31, 2008, 11:27PM
The results of a red-light camera study released this week by the city have puzzled the researchers who conducted it and others around the country.
At a ratio of 10 to 1, study after study on the effect of red-light cameras from Oxnard, Calif., to Philadelphia, Pa., (and all the way to the United Kingdom, where they have been used for years) have found that they drastically reduce crashes.
But according to the Houston study, the red-light program here had no clear impact. Accidents remained relatively flat at the lanes of intersections where cameras were installed and increased by three times in some cases in approaching lanes without cameras.
Why such different results?
Researchers say there are numerous possibilities, all of which need further analysis. The studies may have been conducted differently, or the cameras may have set up differently. Houston driving trends may differ compared to other cities, or the cameras may be less effective in urban areas.
One specialist from a renowned traffic research organization who reviewed the study for the Houston Chronicle said the methodology was "flawed" and has serious "limitations."
The main problem is a statistical one, said Anne McCartt, senior vice president for research at the Insurance Institute for Highway Safety. The institute has conducted several studies that were published in peer-reviewed journals on traffic research.
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