How do you make a 17.9% increase in crashes look like a success? Make up a formula that says so.
A recent report by a citizen of Las Cruces, New Mexico illustrates how far cities are willing to go to protect their ticket camera programs.
At the Las Cruces City Council Work Session, there was a 9-month update on the city’s red light camera program. The results show that total crashes at three intersections have gone up from 39 before the cameras to 46 after the cameras.
However, the city wants to keep the ticket camera program and they know that reporting those kind of results could jeopardize its future so they decided to create a formula that shows that the cameras have improved safety in the city.
This is a screenshot of the results that they presented, along with the formula they created called the Severity Index (SI):
As you can see, even using their made-up formula, two of the three intersections were worse off with cameras. They also failed to include data from a fourth intersection — possibly because the results were even more damning.
Furthermore, the single fatal crash that swings the formula in favor of the cameras was a drunk driving fatality that would have occurred with or without the cameras.
Ultimately, the only statistically-significant change from pre-camera to post-camera is a 36% increase in property damage crashes.
While this report out of Las Cruces is a minor example of statistical manipulation, it’s important to take any report from a ticket-camera city with a grain of salt. They have a vested interest in keeping the cameras so they’re likely to only present statistics that make the cameras look effective.