I don't know how much more you need in the way of stats when people who cause more trouble (for less good reason), ie drunks and frequent fliers, are less often banned than sickle cell patients. I think emergency departments have a right to ban abusive jerks, but the discrepancy in jerk-banning tells you everything you need to know. It reminds me of a conference on the biological roots of violence that raised a storm. People objected to the sessions exploring how much being black contributed to a predisposition toward violence. I don't remember the numbers, but it was along the lines of "25% of violent crime is done by blacks, 75% by others" and blacks were about 12% of the population at the time. Meanwhile, totally ignored was the little statistic that 87% of violent crimes are committed by males, and closer to 95% when female violence that was a response to abuse was added to the male side of the ledger. (The organizers wound up pulling their stupid "gee why are blacks so violent" symposium.)