
Nate Silver @NateSilver538
@AJentleson @daveweigel So, if you actually want to be empirical about this, momentum generally doesn't predict much in polling. e.g. if a candidate goes from 30 percent at Period A to 27 percent at Period B, the best guess is that he'll still be at 27 percent at Period C, ie the polls are a random walk — PolitiTweet.org