Our turnout model

There’s a big question on top of the standard margin of error in a poll: Who is going to vote? It’s a particularly challenging question this year, since special elections have shown Democrats voting in large numbers.

To estimate the likely electorate, we combine what people say about how likely they are to vote with information about how often they have voted in the past. In previous races, this approach has been more accurate than simply taking people at their word. But there are many other ways to do it.

Our poll under different turnout scenarios Who will vote? Est. turnout Our poll result The types of people who voted in 2014 163k Tenney +4 People whose voting history suggests they will vote, regardless of what they say 208k Tenney +1 Our estimate 210k Tenney +1 People who say they will vote, adjusted for past levels of truthfulness 222k Tenney +1 The types of people who voted in 2016 274k Tenney +4 People who say they are almost certain to vote, and no one else 275k Tenney +1 Every active registered voter 395k Tenney +6

In these scenarios, higher turnout tends to be better for Republicans.

Just because one candidate leads in all of these different turnout scenarios doesn’t mean much by itself. They don’t represent the full range of possible turnout scenarios, let alone the full range of possible election results.