Polling of all sorts always contains a margin of error, usually about 3 percent, though it pays to check each poll. Of course, some pollsters can at times be just plain wrong or, worse, even biased. This should make readers wary of their predictions. Since some online comments in response to more than one of my blogs had touted Rasmussen Reports as a reliable source, I’m passing along what Nate Silver of FiveThirtyEight reported on his election night blog for the New York Times. It's something to keep in mind during the next election campaign:
Rasmussen Reports Polls Were Biased.
While waiting for the remaining results to trickle in from states like Colorado and Alaska, I did a quick check on the accuracy of polls from the firm Rasmussen Reports, which came under heavy criticism this year — including from FiveThirtyEight — because its polls showed a strong lean toward Republican candidates.
Indeed, Rasmussen polls quite consistently turned out to overstate the standing of Republicans tonight. Of the roughly 100 polls released by Rasmussen or its subsidiary Pulse Opinion Research in the final 21 days of the campaign, roughly 70 to 75 percent overestimated the performance of Republican candidates, and on average they were biased against Democrats by 3 to 4 points.
Every pollster is entitled to a bad cycle now and again — and Rasmussen has had some good cycles in the past. But their polling took a major downturn this year.