Introduction by Ken Feltman:
This is perhaps the most important news about political polls to come out of the 2016 election: Nate Silver and others at FiveThirtyEight have the statistics to establish that some pollsters, intentionally or not, skew their results.
Before you click to his article, please consider how he ends it:
“So … what to do about it? If you’ve read this far, you’re undoubtedly highly interested in polling. So my message for fellow polling geeks is as follows: Let’s not give pollsters so much grief the next time they publish what looks to be an “outlier.” Polling data is noisy and polling is becoming more challenging. The occasional or even not-so-occasional result that deviates from the consensus is sometimes a sign the pollster is doing good, honest work and trusting its data.
It’s the inliers — the polls that always stay implausibly close to the consensus and always conform to the conventional wisdom about a race — that deserve more scrutiny instead.”
It’s time to stop worrying about outliers and start worrying about inliers. Earlier this year, my colleague Harry Enten documented evidence of pollster “herding” — the tendency of polling firms to produce results that closely match one another, especially toward the end of a campaign. What’s wrong with the polls agreeing with one another? The problem is that it’s sometimes a case of the blind leading the blind. Take a look at the polls conducted in this year’s Senate race in Iowa….