Where the Race for the Presidency Stands

As always, Nate Silver cuts through all of the conflicting poll data and screaming head spin to give a true snapshot of the race as it stands today.  Here’s an excerpt:

The term “momentum” is used very often in political coverage — but reporters and analysts seldom pause to consider what it means.

Let me tell you what I think it ought to mean: that a body in motion tends to stay in motion. That is, it ought to imply that a candidate is gaining ground in the race — and, furthermore, that he is likely to continue to gain ground.

As a thesis or prediction about how polls behave, this notion is a bit dubious, especially in general elections. In races for the United States Senate, for instance, my research suggests that a candidate who gains ground in the polls in one month (say, from August to September) is no more likely to do so during the next one (from September to October). If anything, the candidate who gains ground in the polls in one month may be more likely to lose ground the next time around.

(Where might there be clearer evidence for momentum, as I’ve defined it? In primaries, especially when there are multiple candidates in the race and voters are behaving tactically in choosing among them. But there is little evidence of it in general elections.)

The way the term “momentum” is applied in practice by the news media, however, it usually refers only to the first part of the clause — meaning simply that a candidate has been gaining ground in the polls, whether or not he might continue to do so. (I’ve used this phrasing plenty of times myself, so I have no real basis to complain about it.)

But there are other times when the notion of momentum is behind the curve — as it probably now is if applied to Mitt Romney’s polling.

Mr. Romney clearly gained ground in the polls in the week or two after the Denver debate, putting himself in a much stronger overall position in the race. However, it seems that he is no longer doing so.

Click here to read the full article.