More Liquor Stores = More Violence?

A geographic study of Cincinnati shows that the more liquor stores there are in a given area, the more violence there will be in that area. According to an article on LiveScience, "the statistics showed that adding one more liquor store per square mile would lead to 2.3 more simple assaults and 0.6 more aggravated assaults in the area." The two researchers, a geographer and criminal justice professor attempted to control for demographic and social factors that might indicate increased violence. Nonetheless, I expect that this data would be a challenge to justify based on a study within one metropolitan area. Perhaps studies in additional cities need to be made? What are your thoughts?