NBC Massages Poll Results to Show Obama Leading in Key Swing States
NBC, soon to be joined by the rest of the media, is swooning over three new polls that all show Obama edging Mitt Romney in the critical swing states of Ohio, Virginia and Florida. The leads are very slim: 4 points in Virginia and Florida and 6 points in Ohio. And, leads have dropped considerably since March. Still, the NBC/Marist poll is the first bit of good news the Obama campaign has had in a few weeks. Too bad NBC had to massage the numbers a bit to get there.
First, all of these polls are of registered voters, rather than adults or likely voters. As we've discussed, that implies a 4% bias for Democrats, which effectively makes the race in these states ties. There are however legitimate reasons to poll only registered voters this early out, so that isn't in any way cheating.
The cheating part comes in how to "weight" the sample to make it fit the pollster assumptions about the electorate. The pollster, ideally, would like the sample to match the partisan make-up he expects in the coming election. If you over or under-sample one party, this will skew the results. Boy, were the results skewed.
In the Florida poll, the partisan screen of the sample was D-43, R-35, I-21. Yes, that's right. The pollster assumes that 43% of the voters showing up on election day will be Democrats. In 2008, the absolute high-water mark of the Obama candidacy, when he narrowly won Florida, the partisan breakdown was D-37, R-34, I-29. Does NBC really think that, since 2008, there has been such a massive shift to Democrats? Is that reflected anywhere in the country except the studios of MSNBC?
In Ohio and Virginia, NBC didn't so much add phantom Democrats as wave away a large number of Republicans. In Virginia, the partisan screen was D-31, R-29, I-39. In 2008, the vote was D-37, R-33, I-27. The partisan screens in todays poll in OH were D-37, R-28, I-34. The partisan breakdown of the vote in 2008 was D-39, R-30, I-30.
In both OH and VA, NBC is assuming a big shift from the GOP and Dems to Independents. I think there is a reasonable case to be made that this is a general trend, but the sizable shift from GOP to Independents in the electorate compared with 2008 is puzzling. In 2008, the party was dispirited and fatigued by eight years of Bush. It registered one of its lower turnouts in modern history. Over the past four years, the GOP has been reenergized and has shown strong voter turnout in recent elections. Hard to see they'll register less of a share of the electorate in 2012, compared to 2008.
Exit question for NBC: if OH and VA say voters are shifting from the two parties to Independents, why did Florida move so much in the opposite direction? Are so many Independents really flocking to the Democrat party? Are Democrats really going to increase their share of the electorate by a full six percentage points?
My hunch is NBC only need to tweak things a bit to get Obama ahead in OH and VA. In Florida, they had to get extremely creative and make the exact opposite assumption they made in the other states.