Rasmussen may be right with their "Thompson is always slightly ahead of Giuliani nationally":
Imagine Thompson is leading Giuliani by 5% in all the states won by Bush and Giuliani is leading Thompson by 5% in all the states won by Kerry. Thompson will be ahead of Giuliani nationally because there are more declared Republicans in Bush states than Kerry states.
But national polls donīt matter. Sample size = 1000 -> Iowa -> 1/100 of US-population -> generic 10 people from Iowa incl. in the sample ...
