Dan McLaughlin just clobbers Nate Silver and his hopelessly idiotic enablers on the left, at RealClearPolitics. This is a fairly involved essay, with a beefy methodological section that opens the essay. (Pay attention to the section titled, "Where Polls Come From.")
And this passage is especially crucial:
Nate Silver's much-celebrated model is, like other poll averages, based simply on analyzing the toplines of public polls. This, more than any other factor, is where he and I part company.RTWT at the link.
If you read only the toplines of polls - the single number that says something like "Romney 48, Obama 47" - you would get the impression from a great many polls that this is a very tight race nationally, in which Obama has a steady lead in key swing states. In an ordinary year, the toplines of the polls eventually converge around the final result - but this year, there seems to be some stubborn splits among the poll toplines that reflect the pollsters' struggles to come to agreement on who is going to vote.
Poll toplines are simply the sum of their internals: that is, different subgroups within the sample. The one poll-watchers track most closely is the partisan breakdowns: how each candidate is doing with Republican voters, Democratic voters and independent voters, two of whom (the Rs & Ds) have relatively predictable voting patterns. Bridging the gap from those internals to the topline is the percentage of each group included in the poll, which of course derives from the likely-voter modeling and other sampling issues described above. And therein lies the controversy.
My thesis, and that of a good many conservative skeptics of the 538 model, is that these internals are telling an entirely different story than some of the toplines: that Obama is getting clobbered with independent voters, traditionally the largest variable in any election and especially in a presidential election, where both sides will usually have sophisticated, well-funded turnout operations in the field. He's on track to lose independents by double digits nationally, and the last three candidates to do that were Dukakis, Mondale and Carter in 1980. And he's not balancing that with any particular crossover advantage (i.e., drawing more crossover Republican voters than Romney is drawing crossover Democratic voters). Similar trends are apparent throughout the state-by-state polls, not in every single poll but in enough of them to show a clear trend all over the battleground states.
If you averaged Obama's standing in all the internals, you'd capture a profile of a candidate that looks an awful lot like a whole lot of people who have gone down to defeat in the past, and nearly nobody who has won. Under such circumstances, Obama can only win if the electorate features a historically decisive turnout advantage for Democrats - an advantage that none of the historically predictive turnout metrics are seeing, with the sole exception of the poll samples used by some (but not all) pollsters. Thus, Obama's position in the toplines depends entirely on whether those pollsters are correctly sampling the partisan turnout.
That's where the importance of knowing and understanding electoral history comes in. Because if your model is relying entirely on toplines that don't make any sense when you look at the internals with a knowledge of the past history of what winning campaigns look like, you need to start playing Socrates.
Plus, check out Sean Davis, at the Daily Caller, "Is Nate Silver's value at risk?" (via Memeorandum). Well, of course it's "at risk." I've been slamming Silver's "value" for weeks now. I just don't want anything bad to happen to him, but it may be too late. The dude's starting to lose it and the editors are giving him the backhand like a whiny bitch getting slapped. Hard. (Background here, "Nate Silver Bets Joe Scarborough $2,000 That Obama Wins.")
See also Mark Blumenthal, "Could Presidential Polls Be Wrong About Obama's Battleground Edge?" (Blumenthal gives significant odds that models like Silver's will fail miserably on election day, mostly on a theory of the fundamental freakishness and unpredictability of the human experience (see the part about the "black swan").
* "Nate Silver Bets $2,000 on Obama's Reelection, Provokes Public Editor's Ire."
* "Nate Silver Fast on His Way to One-Term Celebrity."
* "Akron Beacon Poll Finds Ohio Dead Heat at 49-49 — Presidential Race Tighter Than Obama's A**hole in a Prison Shower."
* "Nate Silver: Voice of the New Castrati."
* "If Bias Doesn't Matter Why Would Bill Maher Host Nate Silver on 'Real Time'?"
* "Oh My! Romney Back Up to 51 Percent in Gallup's Daily Tracking — Nate Silver Hardest Hit!"
* "'Grand Swami' Nate Silver Boosts O's Chances to 71.0% in Electoral College!"
* "Obama Crashing in Ohio; or, For the Love of Mercy, Leave Nate Silver Alone!"
* "Nate Silver Calls It: Advantage Obama!"
* "Nate Silver's Flawed Model."
* "Boom! Romney Back Up 52-45 in Gallup's Daily Tracking of Likely Voters."
* "ABC News Touts Nate Silver's Prediction That Obama's Handicapped at 68 Percent Chance to Win!"
* "'It's becoming increasingly obvious that Silver can't be taken seriously...'"
* "Nate Silver Blows Gasket as Gallup Shows Romney Pulling Away in the Presidential Horse Race."