That said, here are four possible factors:
1. Bradley Effect: It seemed like a nice wonky little point when Polipundit speculated on the Reverse Bradley Effect--the idea that Iowa's public caucuses led Dem voters to demonstrate their lack of prejudice by caucusing for Obama. Now this is the CW of the hour. Polipundit wrote:
I suspect that Obama may have scored better than he would have in a secret-ballot election, and benefited from a Reverse Bradley Effect.
New Hampshire, of course, is a secret ballot election. Voters might have told pollsters one thing but done another in private.** New Hampshirites I ran into Tuesday night mentioned that the state was very late ratifying the MLK Holiday.
2. Lazio Effect. No ganging up on the girl! First, Edwards turns on her in the debate. Then Obama says she's merely "likeable enough." Then the press disparages her anger, mocks her campaign and gloats over its troubles. They made her cry! And then that mean macho John Edwards goes and says the crying makes her unfit to be president. (I was told voter leaving Edwards in the closing hours went disproportionately to Hillary, not Obama.)
3. Feiler/Skurnik Effect: What's stunning is the ferocity and speed with which Hillary's fortunes turned around in those final hours. Kf has a theory to explain that! Actually, two theories. The familiar Feiler Faster Thesis holds that voters are comfortable processing information at the vastly increased speed it can come at them. Jerry Skurnik's "Two Electorate" theory holds that voters who don't follow politics are much less informed than they used to be, which causes polls to shift rapidly when they do inform themselves. Put these two together and you've got a vast uninformed pool of voters that only begins to make up its mind until the very last minute--after the last poll is taken, maybe--and then reaches its decision by furiously ingesting information at a Feileresque pace. In fact, the percent of voters who made up their minds at the very end in N.H. was unusually large. (Add convincing statistic here!)
Two implications of the Feiler/Skurnik combo: a)Momentum from the previous primary doesn't last. When the early primary dates were set, the CW held that the Iowa loser would never be able to stop the Iowa "wave" effect in the five days between the two primaries. It was too short a time. In fact, it wasn't short enough. A three day separation and maybe Obama would have won. As it was, by the time the uninformed voters tuned in on Sunday and Monday, Iowa was ancient history.*** b) Instead, these voters saw clips of Hillary having her emotional tearing up moment. In other words, the Feiler/Skurnik Effect magnifies the significance of any events that occur in the final day or two of the campaign. After yesterday's election, expect more of these events.
4) The Congestion Alert Effect: I remember when the Southern California transportation authorities installed a state-of-the-art series of electronic signs alongside the freeways to give motorists instantaneous warnings of traffic delays. The signs don't do that any more. Why? It turned out that when you warned drivers of congestion on Route A, they all took Route B, leading the latter to become congested instead of the former. Similarly, independent voters in N.H. were told by the press that the Democratic race was a done deal--so they voted in the closer, more exciting Republican race. Which made the Republican race not so close and the undid the deal in the Dem race. (Brendan Loy published this theory first.) [ via Insta]
5)Bonus CD-only Theory--The Orthodox Shul Effect: Alert emailer B.L. writes:
The independents broke the way worshipers do at an orthodox (anything) religious ceremony. The ladies went left and the lads went right (most female indies voted in the Dem primary; most male indies in the Repub).
In other words, it wasn't the lower number of independents voting in Democratic primary that hurt Obama, but which independents voted Dem. McCain's race sucked away precisely those independents most likely to vote for Obama--men (and also, we might speculate, relatively conservative women).