The Myth of the “Statistical Dead Heat”
From the National Council On Public Polls:
Certainly, if the gap between the two candidates is less than the sampling error margin, you should not say that one candidate is ahead of the other. You can say the race is “close,” the race is “roughly even,” or there is “little difference between the candidates.” But it should not be called a “dead heat” unless the candidates are tied with the same percentages. And it certainly is not a “statistical tie” unless both candidates have the same exact percentages.
And just as certainly, when the gap between the two candidates is equal to or more than twice the error margin – 6 percentage points in our example – and if there are only two candidates and no undecided voters, you can say with confidence that the poll says Candidate A is clearly leading Candidate B.
When the gap between the two candidates is more than the error margin but less than twice the error margin, you should say that Candidate A “is ahead,” “has an advantage” or “holds an edge.” The story should mention that there is a small possibility that Candidate B is ahead of Candidate A.
Too bad none – and I mean none – of our mainstream media “election experts” have ever treated polls in this manner, which is more statistically sound but far less entertaining and ratings-generative.