Who gets aggressive at bars?

http://bps-research-digest.blogspot.com/2012/10/who-gets-aggressive-at-late-night-bar.html  summarizes some work by Kathryn Graham and her colleagues.

Some of this is routine: three quarters of the aggressive actions are from males.  Some of it seems naïve to me:

because so much female aggression was provoked by sexual harassment, the researchers advised establishments to create at atmosphere that discourages "invasive and aggressive sexual overtures whilst still maintaining an exciting venue where young people can explore their sexuality and meet potential partners."

But the surprising part to me involved the base rate: 

Kathryn Graham and her colleagues trained 148 observers and sent them out to 118 bars in early-hours Toronto where they recorded 1,057 instances of aggression from 1,334 visits.

In other words, there was an average of 1057/1334 = .8 acts of aggression per visit.  I wondered where these bars are – that seems extraordinarily high, or the standards for what “aggression” is might be very low.  The full article just specifies the bars were large capacity bars/clubs (>300 people) in Toronto in 2000-2002. The visits were 3 hours each, midnight to 3 a.m.

I guess I’m naïve, since I realize I have never spent the hours of midnight to 3 a.m. in a large capacity bar or club.  Nothing about this article makes me more likely to do so.