One of the most frequently cited pollsters in comments on this blog is Rasmussen. Not only is that company the most prolific pollster in the United States, it’s also one of the most controversial.
Nate Silver at Five Thirty Eight Blog recksons Rasmussen leans about +2 to Republicans candidates. Silver must be talking about in national polls. Because in the swing states, in the 2008 presidential election, Rasmussen leaned toward John McCain in 11 so-called “battleground states” by a wider margin.
The average Rasmussen lean for McCain was +4.08. Of the 11 contests, Rasmussen actually called the election the wrong way in 4. He had McCain ahead in Indiana, Florida and North Carolina, but Obama won all of those states by slender margins. Ramussen’s last Ohio poll called the 2008 race a tie. Obama won by 4.6
But don’t take my word for this. Look it up yourself.
Below is a list of the battleground states in 2008, followed by Obama’s actual winning percentage, Rasmussen’s closest-to-the-election prediction, and the difference between those two (the skew). You can click on the states to check my numbers, which come from Real Clear Politics.
Colorado result: Obama +9, Rasmussen: Obama +4 (skewed McCain by 5 points)
Florida result: Obama +2.8, Rasmussen: McCain +1 (skewed McCain by 3.8 points)
Indiana result: Obama +1.1, Rasmussen: McCain +3 (skewed McCain by 4.1 points)
Iowa result: Obama +9.5, Rasmussen: Obama +8 (skewed McCain by 1.5 points)
Nevada result: Obama +12.5, Rasmussen: Obama +4 (skewed McCain by 8.5 points)
New Hampshire result: Obama +9.6, Rasmussen: Obama +7 (skewed McCain by 2.6 points)
North Carolina result: Obama +0.3, Rasmussen: McCain +1 (skewed McCain by 1.3 points)
Ohio result: Obama +4.6, Rasmussen: tie (skewed McCain by 4.6 points)
Pennsylvania result: Obama +10.3, Rasmussen: Obama +6 (skewed McCain by 4.3 points)
Virginia result: Obama +6.3, Rasmussen: Obama +4 (skewed McCain by 2.3 points)
Wisconsin result: Obama +13.9, Rasmussen: Obama +7 (skewed McCain by 6.9 points)
The remarkable thing here is not that Rasmussen didn’t nail any of those elections. Pollsters only predict within a stated margin of error. If a poll predicts a candidate will get 46 percent, and the margin of error is 3 points, that means there’s a 95 percent probability a candidate’s “true” percentage will fall somewhere between 43 and 49 percent.
What IS remarkable are the following:
- In 5 of the 11 contests, Rasmussen’s final poll showed numbers that were OUTSIDE the margin of error. That’s bizarre. You’d expect them to have a 95 reliability. Instead it’s 55 percent.
- The next one is the biggie: The Rasmussen polls in battleground state ALL were skewed to McCain.
- And that’s how you know there’s an actual “Rasmussen skew.” If 6 of them leaned too much to McCain, and 5 leaned too much Obama’s way, it would be roughly even and there wouldn’t be any evidence of a skew.
FINALLY, because Rasmussen is the most prolific pollster, there’s a good chance that in any given state, that skew is reflected in the Real Clear Politics Average.
So stick that in your back pocket between now and Tuesday and consider the following the next time you read a Rasmussen poll. In the 2008 presidential battleground states:
- They had a only a 55 percent chance of being within the margin of error on the final state poll.
- They had the final outcome wrong in 4 of 11 states.
- And, they ALWAYS skewed to McCain.