Mixed use and crime linked?

Here some interesting research out of Ohio State University that studied the effects on crime given different levels of residential and business activity in neighborhoods. It seems to support a link between increased density, a balance of uses, and a lower level of violent crime. I question whether density alone can explain the trend. I think urban design factors affect the potential for crime quite a bit as well, ie. lighting, landscaping, window placement, parking configurations, etc. There is currently a trend in cities to implement Crime Prevention Through Environmental Design (CPTED) techniques and guidelines that address some these issues. You can learn a lot about it here.