Government Speed Camera Claims Halved by Dr Linda Mountain

.....in a country the size of Britain, clusters of accidents are not always caused by dangerous roads or speed. Driver error, weather conditions or simple bad luck can also play a part.

If a camera goes up at one of these fluke sites, and accidents drop, the official statistics will claim that the camera has been successful.

But it is likely that the accident rate would have fallen anyway. The effect, known as 'regression to the mean', is well known to statisticians but not taken into account in camera statistics.

'If accidents fall dramatically after the cameras are in place, it could be that the cameras have reduced accidents, but some of the fall may simply show that a run of bad luck has come to an end,' Dr Mountain told the British Association science festival in Liverpool.

Daily Mail 19/09/02: Speed cameras 'have saved only HALF the lives ministers claim'

See my earlier post suggesting even halving the claims may be far too much:

http://abdmercia.blogspot.com/2008/09/detailed-examination-of-speed-camera.html