… Human brains and eyes naturally gravitate to margins — because margins quickly summarize the data. But like all summaries, they can obscure, or ignore, important information.
There’s a difference between a contest where a candidate leads 53 percent to 45 percent, with 2 percent undecided, and one where the lead is 46 percent to 38 percent with 16 percent undecided. The eight-point margin is the same, but the contours of the race, and the outcomes, could well be quite different.
Focusing on margins while failing to understand the role of undecideds is not an error in the poll, it’s a mistake in analysis and interpretation. CONTINUED
Mark Mellman (Mellman Group), Washington Post