A fascinating post from a blogger who examines the commonly cited rule in political punditry that undecided voters tend to ?break? towards challengers against well-defined incumbents. This rule justifies worrying about incumbents with below-50 percent marks, but careful analysis suggests something else:
In essence, pundits have made the fallacy of the inverse (or converse, I can never remember which). An incumbent above 50% in the polls is generally safe because it is much more difficult to persuade someone who is supporting an incumbent to switch their vote than it is to persuade someone who hasn’t made up their mind. It doesn’t follow, however, than incumbent not above 50% is generally not safe. And the evidence, in fact, supports the contrary: They can expect to generally recover a fair amount of the undecided vote. Unless a candidate is well below 50% in the polls, or locked in a tight race in the high 40s, she can feel pretty good about the election.
Lots of applications here. As they say, read the whole thing.
