Likely voter

A likely voter is a respondent whom a pollster judges likely to cast a ballot, as opposed to a registered voter or an adult in general. Polls early in a campaign usually survey adults or registered voters; as Election Day nears, many switch to likely voters because turnout is far below 100 percent.

Pollsters decide who is likely using a set of questions, such as how interested the person is in the election, whether the person voted in past elections, how sure they are to vote and whether they know where to vote, or by using voter-file records of voting history. Methods vary, and each firm's "likely voter model" is partly proprietary. The choice can change the results by a few points, because the groups that turn out differ by party.

Supporters say that screens produce a more accurate reading of the electorate. Critics say they can introduce guesswork, particularly in unusual years when turnout patterns shift, as in some recent midterms and special elections. Differences between registered-voter and likely-voter results can reflect an enthusiasm gap. Along with the margin of error, it explains why polls differ. It is important for the generic ballot and for forecasting a midterm election.