
Nate Silver @NateSilver538
By "momentum is a bit overrated", I mean this: If a candidate went from polling at 10% *last* month to 15% this month, you might assume she's bound to improve to 20% *next* month. Empirically, that's not true, though. She's roughly as likely to go back down to 10% as up to 20%. — PolitiTweet.org