There's lies, damned lies and...

In a paper the other day I saw that hoary old chestnut about 80% of road accidents happening within 10 miles of home.  So why "hoary old chestnut"?  Is it false? Well no - it's actually quite true, but meaningless.  Why?  Well think about it - chances are that about 80% of the driving anybody does is within 10 miles of their home, so if you have an accident it's more likely to be in that area simply because you are more likely to be driving in that area.  A similar "fact" that comes from Australia is that 97% of shark attacks take place in shallow water - well shucks, couldn't just be that that's where 97% of swimmers are, could it?