(Suffolk’s Methodology taken to task. A good analysis by Jim Gehrraty in the comments.
– promoted by Rob “EaBo Clipper” Eno)
I’d be curious to hear some input on this with folks more familiar with polling.
Pollsters do their best to solve this problem by screening out those who are unlikely to vote using a question or series of questions probing interest in the election and/or prior voting behavior. These techniques vary widely from pollster to pollster. Some pollsters use especially “loose” voter screens: asking only, for example, if someone is certain to vote, without probing any deeper.
For example, simply asking respondents if they are certain to vote (used by Suffolk) will sometimes let more than 90 percent of respondents through a screen. In such a situation, nearly half of the respondents who are counted will not actually vote. Even tighter voter screens tend to let through a significant number of respondents who will not actually vote.
All of this is consistent with what we’ve seen in pollsters’ measurements of the enthusiasm gap. Pollsters who ask respondents to rate their interest in voting on a scale of 1-10 are consistently finding Republicans far outpacing Democrats among those who describe their interest as a 10, with Democrats performing better among low-interest voters. Some pollsters, even those who are showing bad results for Democrats, are letting these low-interest voters through to their samples. This is true even though research indicates that only 1/3 of those who describe their interest level as seven or below on a scale of 10 will actually vote, compared to 84 percent of 10s and 71 percent of 9s.
In sum, no one can know for certain what the electorate is going to look like this year until after Election Day. But it appears that the variations in some pollsters’ likely voter screens may be envisioning an electorate that is less slightly Democratic than the 2008 electorate but more Democratic than 2004. Such a model could well turn out to be true.
But an alternate reading is that the exit poll data from 2009, as well as other data pointing to a significantly more energized Republican party, suggests the electorate this year may be far closer to 2004. If this turns out to be a more accurate assessment of the electorate, we could well see some Republican candidates outperforming the polls by 3-4 point margins similar to the results for Bob McDonnell in Virginia and Chris Christie in New Jersey last November.