Just to put some numbers to this (albeit with no causation factors), this is a tabulation from a report on
BBC News about the fixed cameras being switched on again in Oxfordshire. The "Cameras On" numbers relate to the period August 2009 to January 2010 and the "Cameras Off" numbers relate to the period August 2010 to January 2011:
At Camera Sites Cameras On Cameras Off
Collisions 60 62
Slight Injuries 55 70
Serious Injuries 13 13
Fatalities 0 0
Elsewhere Cameras On Cameras Off
Collisions 885 867
Slight Injuries 999 982
Serious Injuries 160 179
Fatalities 12 18
If anyone claims to deduce anything statistically significant from those numbers then they're probably delusional
What
is statistically significant is that the Thames Valley Scamera Partnership's funding stream is flowing again