It immediately struck me -- is the _average_ time to crime the interesting bit of information here? if 4 people buy handguns and then immediately rob liquor stores, and 1 guy steals his grandfather's handgun which was registered 30 years ago and has never been involved in crimes, and then robs a liquor store with it, the average will tend to obscure attempts to discover if 'people buying guns so that they can go commit crimes with them' is a real problem or not.
Useful summary Jeff
It immediately struck me -- is the _average_ time to crime the interesting bit of information here? if 4 people buy handguns and then immediately rob liquor stores, and 1 guy steals his grandfather's handgun which was registered 30 years ago and has never been involved in crimes, and then robs a liquor store with it, the average will tend to obscure attempts to discover if 'people buying guns so that they can go commit crimes with them' is a real problem or not.