polling Definition and 2 Threads

Suppose your polling methods were so good that all one had to worry about was random experimental error. Then how many sample subjects would you need to have 95% confidence that your sample mean was within 1% of the true population mean? Answer : Ten thousand sample subjects. That though...

What exactly is a "margin of error" intended to be for a poll? Is it a one sigma number? A 90 or 95% CL? An educated guess? As I understand it, this number is reported on each result - i.e. if the poll says Smith and Jones each have 50% support with a 5% MOE, the "true" result can be anywhere...