J. Ann Selzer, who has conducted polling on the Iowa caucuses since 1988, says the contests almost always yield surprises. With each election, it increasingly becomes more difficult to reliably predict the outcome, and this year is the toughest yet.
Pollster.com lists 20 Iowa Republican caucus polls for January alone. Nate Silver’s blog, FiveThirtyEight, bases its Iowa predictions on a weighted average of 19 polls.
According to Selzer, who has done polls for Bloomberg and the Des Moines Register, the large number of surveys makes it more difficult to get reliable results: “With low incidence populations like the caucuses, I’m worried about polling fatigue.”