Dear Dr. Mike;
You are too late - screaming for help is already outlawed - screaming for help is known as distrubing the peace and creating a public nuisance - scream and you will be arrested - afterall - this is San Francisco - where we must maintain political correctness - and disturbing your neighbors karma is a no no.
If you are going to be beaten and mugged do so quietly - the person doing the beating and mugging is trying to overcome their childhood difficulties and their authority problems - you and your money and the beating you get are deserved for creating this persons problems - it's your fault you are being robbed and mugged - the mugger needs their theraphy and you are it. 
Ron Getty
SF Libertarian