Midterm Polling Error is Much Larger

Sam Wang: “Yesterday, Nate Silver and I both examined Senate polling errors. He saw no overall bias; I pointed out that recent bias has been unusually large. Both statements are true. But neither of us pointed out that the biases follow a significant pattern: midterm-year polling is far less accurate than Presidential-year polling.”

“From a practical standpoint, this is good news for those of you who don’t like where things have headed lately: in midterms, Senate polling errors are five times larger than in Presidential years. There is bad news too: the error can go in either direction, and a GOP blowout is also possible.”