Pollsters and pundits spend lots of time studying margins — how far ahead or behind a given candidate is relative to his or her opponent. Focusing on margins is a dangerous game, however, and one of the reasons polls appeared off the mark this past year.
Surveys are designed to elicit point estimates, the level of support for each candidate. The margin has no particular statistical standing. It is merely the difference in the level of support garnered by each candidate. And therein lies the problem. CONT.
Mark Mellman (Mellman Group), The Hill