In the Iowa caucuses, John Edwards got 30% of the delegates and Hillary Clinton got 29%. Had Clinton picked up one more delegate, her percentage would have also rounded up to 30%. Here is a story (“The Girl Who Sank Hillary”) about how the decision of one caucus goer prevented Clinton from getting that 30% and an effective tie.

I think the authors are attributing a little too much significance to that single vote. However, the story still provides a good description of interactions and decision-making at one caucus.