Just a reminder about Rasmussen Polls. They suck. Here’s a snippet from Nate Silver’s post-2010 midterms analysis:
The 105 polls released in Senate and gubernatorial races by Rasmussen Reports and its subsidiary, Pulse Opinion Research, missed the final margin between the candidates by 5.8 points, a considerably higher figure than that achieved by most other pollsters. Some 13 of its polls missed by 10 or more points, including one in the Hawaii Senate race that missed the final margin between the candidates by 40 points, the largest error ever recorded in a general election in FiveThirtyEight’s database, which includes all polls conducted since 1998.
Moreover, Rasmussen’s polls were quite biased, overestimating the standing of the Republican candidate by almost 4 points on average. In just 12 cases, Rasmussen’s polls overestimated the margin for the Democrat by 3 or more points. But it did so for the Republican candidate in 55 cases — that is, in more than half of the polls that it issued.
If one focused solely on the final poll issued by Rasmussen Reports or Pulse Opinion Research in each state — rather than including all polls within the three-week interval — it would not have made much difference. Their average error would be 5.7 points rather than 5.8, and their average bias 3.8 points rather than 3.9.
Nor did it make much difference whether the polls were branded as Rasmussen Reports surveys, or instead, were commissioned for Fox News by its subsidiary Pulse Opinion Research. (Both sets of surveys used an essentially identical methodology.) Polls branded as Rasmussen Reports missed by an average of 5.9 points and had a 3.9 point bias. The polls it commissioned on behalf of Fox News had a 5.1 point error, and a 3.6 point bias.
I mention this because not a few right-wingers are hanging their hats on the fact that Rasmussen shows better results for Mitt Romney and other Republican office-seekers than the consensus of other polls. That appears to be the point of Rasmussen Polls, especially since most outfits are now using aggregates of all the polls that are released. Nate and I actually had a liquor-soaked conversation about Rasmussen’s shitty-polling during a party at the Netroots Nation conference in Pittsburgh (in 2009). Yet, he recently admitted that his current model allows Rasmussen to have quite a bit of influence.
…the Gallup and Rasmussen Reports polls can have a lot of influence on the forecast at times when there is a potential turning point in the race. The trendline adjustment that the model calculates compares changes in the results produced by the same polling firms over time. Since the Gallup and Rasmussen Reports national tracking polls have been published almost every day since the spring, they represent highly important data series in this process.
Nate does have a way to correct for consistent bias over time, but merely by being a Republican-supporting data point that plays an important role in his model, and in the other aggregators which mostly do not correct for such bias, Rasmussen’s overall effect is to skew the picture of the political landscape in a rightward direction.
In other words, if you’re reading analysis that takes Rasmussen seriously at all, you’re a dummy. Nate hopes that a consistently flawed polling methodology can nonetheless provide trend lines as long as the methodology remains consistent. In other words, even if Rasmussen is consistently showing results that are four points too optimistic for the Republican, if you account for that you can see when the contests are growing closer or farther apart.
I’d prefer it if their results were simply ignored and their outfit ostracized as bad-faith operators. It’s not that I don’t believe that Nate can utilize their data usefully, but he’s the only one who is making the correction for bias. I do not believe you have any such correction at Real Clear Politics or Talking Points Memo, although I will update and correct this post if I am wrong.
It seems to me that Rasmussen’s polls are designed to skew the perception of the state of play in the Republicans’ direction, which can help fundraising, press coverage, and morale among activists. It’s dishonest and dishonorable, and it is also effective.
People, including, Nate, should know better than to treat them as an honest data point.
