It was infuriating: day after day, time after time during the run-up to the election--things would look great for team Obama, and then...ka-boom: another Rasmussen poll. A dagger in the heart. Yes, I tried to ignore them, aware of their history of conservative bias, and I succeeded to some extent. But it wasn't easy, especially with so many wise, sage commenters (here, on Twitter, and elsewhere) admonishing against ignoring any polls, ever.
But after awhile, it got so ridiculous (Colorado: Romney +3!, Wisconsin: Tied!), that my thinking changed. "Good!," I thought to myself. "Let the Razz-holes keep publishing these ridiculous numbers--the more ridiculous the better--so that they will be completely discredited when the actual results come in!"
With the dust now close to having settled (although there are still votes being counted, and the results continue to move in Obama's favor as results come it), I thought I'd do some very rudimentary number-crunching and have a look at how truly biased and inaccurate Rasmussen's numbers were. So have a look. I checked the current results from all the swing states (I'm classifying as a "swing state" each of the twelve states listed in that category by David Wasserman on his public spreadsheet, which contains the most recent vote-counts of which I'm aware), rounded to two decimal points. I then listed Rasmussen's final poll for each of these states, and for good measure included PPP, whose results were almost without exception described by the traditional media as "left-leaning." I then calculated the "bias" (the difference between the pollster's result and the actual result) for each state for both pollsters. I then calculated the average bias among all twelve "swing states" for each pollster.
For purposes of simplicity, each cell of the spreadsheet gives the margin between Obama and Romney, with positive numbers indicating an advantage for Obama and negative ones indicating one for Romney. (An asterisk next to a state name means that state has certified its final results.) So in Colorado, for example, Obama is winning by 5.38 percentage points, PPP's last poll had Obama by 6 points there, and Rasmussen's last poll had Romney by 3).
Have a look: the results make clear that Rasmussen absolutely and positively sucks. They were off by over eight points in Colorado, nearly seven in Iowa and Wisconsin, six in Virginia, five (rounded up) in Michigan and Nevada, four in North Carolina and New Hampshire. And in every swing state--every single one--they were biased in favor of Rommney. In fact, the Razz-holes only even predicted the correct result in terms of simple winner/loser in six of the twelve states! You would do as well flipping a coin as paying any attention to Rasmussen's polls! (What's worse, they were only 3 for 9 if you include the states most outlets considered swing states during the election; omitting, that is, Pennsylvania, Michigan, and Minnesota from consideration, which tells you you'd be better off flipping a coin than taking Rasmussen seriously.) overall average bias in Romney's favor ended up being a ridiculous 4.43 percentage points.
Note how much closer to the mark PPP is--less than one point. And notice as well that this supposedly "left-leaning" pollster's very small bias was in Romney's favor.
So next time around, please, don't worry about Rasmussen. It really is sensible simply to ignore them, since you're demonstrably better off rolling dice or flipping coins.
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