caveat
when you do these kinds of analysis, you can't do a comparison of one county and another county in the same state, or even one city and another city in same county. The reason for this is that there are other factors which increases the predisposition of a person to commit crime as an adult.
One of the strongest factors is the initial family structure in which the future crinminal grew up in. Male children from divorced/out-of-wedlock/step family, and single parent family are at particularly high risk. Primary reason for this is that odds of a person growing up to be a dysfunctional adult increases drastically in the case of blended and other form of a non-traditional family.
So the only real solid way to look at statistical results is look at crime data before and after the ban for the same region, providing there was no significant changes in other demographic factors such as family structure.
--John
