Easily my biggest pet peeve in polling is dishonest sampling to achieve a certain outcome (invariably in favor of a Democrat). Jim Geraghty over at National Review is regularly on top of these embedded biases and has a fantastic post explaining the party ID bias in most every poll thus far in the early phases of the general election. The actual post spends some time demonstrating how Pew polls have skewed on average +5 in favor of Democrat presidential contests since 1992 (which then skews the real Clear Politics average). But what interested me even more was the overall oversampling this election season:
On another polling annoyance, I turn to your favorite punching bag PPP-D. Here is the trend with PPP-D. They do a terrific job polling our primaries (this is not sarcasm). Their closing polls are usually okay. But their tracks, should be involving a Republican versus Democrat race be viewed with healthy skepticism. The latest poll release in NC showing Obama +1 indicated a Democrat advantage of +12. I don’t know what they are smoking over there but I want some (just kidding) . . .As I tracking every public poll, I have found it amazing on how many pollsters are oversampling Democrats. On average, every poll is indicating a partisan ID similar to 2008. Based on my analysis, the average gap is +6.4% Democrat which compares to the +7% which was in 2008. Alas, for the RCP poll average to be correct you have to assume the self-identified party preference turnout will be similar to 2008, if the turnout is similar to 2004 or 2000 or 2010, Obama’s polling leads may as well be part of his “story telling.” For the pollsters that look at preference, Rasmussen has indicated that the self-identified party ID (for Adults – not likely voters) is about +1.4% Republican.
Based on my track if the election were held today Romney wins by 5 percentage points.
Geraghty then makes a slight defense of PPP
I’ll make a quite modest defense of PPP on North Carolina, in noting that there are a lot of conservatives down there who are still registered Democrats. The margin in the 2008 exit polls was 42 percent Democrat, 31 percent Republican. According to the latest voter-registration statistics, the state has 2,729,427 registered Democrats (43.4 percent) 1,972,428 registered Republicans (31.3 percent) and 6,284,428 total registered voters. Of course, not all registered voters actually cast ballots each year, and quite a few of those registered Democrats are pretty conservative. So yes, D+12 is probably too disproportionate, but the parties will probably not be evenly split on Election Day, even if Romney wins handily.
Now I am fully on board with this analysis, although I’m thinking Romney is more likely up only 2-3 points. But overall it is hard to argue with the substance of these critiques. And it would also explain the seeming desperation out of the Obama campaign and the odd passiveness of the Romney campaign. Maybe the internals for both campaigns are telling a very different story than the biased public polling we are left to digest?