Primary Polls Still Aren’t Very Predictive

Nate Cohn: “You have undoubtedly heard that primary polls aren’t necessarily very predictive far from an election. With just a month to go until the Iowa caucuses, I’m writing to tell you that … it’s still true.”

“This phase of the race — the final stretch before Iowa and New Hampshire — can be the most volatile of the entire campaign, as early-state voters make up their minds, politicians and newspapers make endorsements, and candidates make strategic decisions to invest time and money in particular states.”

“In recent primary campaigns, going back to the 2004 Democratic primary, those candidates who have led in Iowa or New Hampshire polls with just one month to go have lost as often as they have won. On average, candidates’ share of the vote at this stage differed from their final share of the vote by around seven percentage points. With many candidates running, it was not at all uncommon for a candidate to move by more.”