Weather and crime: what did happen in 2007?
My theory on knife crime and rain has been somewhat dampened by statistics sent to me by a friend and former colleague of mine, the weather expert Philip Eden.
He has kindly dug out the England and Wales rainfall stats for the two quarters in question:
July 2007 133 millimetres (232% of the long-term average)
Aug 2007 61 mm (84%)
Sept 2007 45 mm (55%)
July 2008 102 mm (178%)
Aug 2008 120 mm (166%)
Sep 2008 105 mm (127%)
This echoes the valid point made by MarkFrank in his posts (thank you for those) but I am not going to give up on my proposition entirely. July 2007 was clearly very wet, more than twice the average, and I wonder whether the weather was just too grim for people to venture down to the pub.
That having been said, Philip reckons that even in that unusually damp month, it was only raining for about 6.5% of the time in London - compared with 3.5% normally.
If anyone can lay their hands on monthly stats which relate to alcohol consumption (sales / profits?), that would be a help.
Clearly something happened in the summer of 2007 which pushed the number of robberies at knife-point down 10-15% from what one might have expected. I doubt it was an unexpected outbreak of goodwill.
In any case, my broader point is that the 18% year on year increase in knife crime which has been so widely reported as evidence of a worsening crime trend, may simply reflect an anomalous situation in the summer of 2007.