if only 50% of the subjects gets HIV does that mean sugar pills have a 50% chance of stopping HIV?
No. It means that the other 50% of the subjects caught HIV from the sugar pill.
...cows alone are causing more global warming than the poorest half of the population of the entire planet...
At least I can eat the cows.
Top Ten Things Overheard At The ANSI C Draft Committee Meetings: (7) Well, it's an excellent idea, but it would make the compilers too hard to write.