In Defense of Iowa Polling

Sam Wang: “There seems to be a persistent meme that polls are in trouble. There was no evidence for this. Primaries and caucuses are volatile situations – this is a well-known fact. I have been assuming that home-stretch polls can be off by an average of 5 percentage points. Any fuss tonight is based on the fact that in Iowa, with its tiny turnout and odd voting procedure, Trump was polling 3 points ahead of Cruz, and ended up losing by 3 points. It would be a mistake to conclude that Trump’s support is illusory in other states. Quite the opposite. A 6-point error would not affect his ranking anywhere else. For now.”

Politico: “According to calculations from the website FiveThirtyEight back in 2014, the average polling error in presidential primary and caucus polls in the final three weeks before an election has hovered between 7 and 9 percentage points.The results for the Iowa GOP caucuses fall within that error range.”