Nate Cohn

Nate Cohn @Nate_Cohn

These choices sometimes put pollsters at odds with poll aggregators. A poll aggregator prefers an unbiased poll, even if it's noisy. A pollster wants to reduce error, and might make choices that induce error to poll it off-- weighting by party identification, to take an easy one — PolitiTweet.org

Nate Cohn @Nate_Cohn

The challenge for education is that the effect on *error* is potentially quite small (oh I was only off by 3 points, in the MoE, I'm fine!), even as the effect on bias is fairly large (oh i took 10 polls and they all leaned Democratic, even if off by 3 on average...) — PolitiTweet.org