After a summer in which the polling in the presidential race was exceptionally stable — with Barack Obama generally holding a lead of about two percentage points in national surveys — the numbers since the party conventions have been a wild ride. …
Polling data is often very noisy, and not all polls use equally rigorous methodology. But the polls, as a whole, remain consistent with the idea that they may end up settling where they were before the conventions, with Mr. Obama ahead by about two points. Such an outcome would be in line with what history and the fundamentals of the economy would lead you to expect. [cont.]
Nate Silver, FiveThirtyEight (NYT)