Will the growing number of voters reachable only by cell phone make polls less accurate? (Only in Obama's direction.)
Are likely voter models missing a surge of new voters? (Probably not.)
What about the Bradley Effect? (There's very little evidence for it.)
And the nightmare scenario for Democrats...
What if those who refuse to take pollsters' calls -- remember, response rates for polls are usually less than 50% -- vote disproportionately for McCain?
This concern is far from trivial, as even the most rigorous national surveys struggle to achieve response rates over 30 percent. And it is hard to know much for certain about those who do not respond because, obviously, we cannot interview them.
One way that pollsters can study the potential impact of non-response is to look at the most difficult-to-interview respondents. In 1997, the Pew Research Center conducted an experiment that involved an unusually rigorous attempt to "convert" to respondents those who initially refused to participate in the survey. They found "strikingly different views" among white respondents "on several race-related questions, with reluctant respondents significantly less sympathetic than amenable respondents toward African-Americans."
Pew could not replicate those findings in a follow-up study conducted in 2003. Still, Andrew Kohut, president of the Pew Research Center, says Pew has always had a harder time completing interviews with a cohort of older, white, less well-educated respondents who typically demonstrate less tolerance on race-related questions. Kohut told me that they identify a demographic cohort that should be 29 percent of adults, but typically represents 20 to 25 percent of adults in their unweighted samples. While they always weight this group up to its appropriate level, he could not rule out the possibility that the missing respondents may be those with less racial tolerance, as they were in Pew's 1997 study.
Although Kohut remains uncertain about how much of problem these harder-to-reach respondents might be, he considers it something "small to worry about" that might mean at most a percentage point or two in the results, not a game-changer for a candidate with a lead as large as Obama's.
Hopefully, we learned from this year's New Hampshire primary to never say never about the potential for a polling failure. Still, all signs from the polls point to an Obama victory.
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We get these stories all the time just before an election, and they really don't matter nearly as much as this. The NH primary was a specific case with some weird aspects to it (artificial boost to Obama's numbers from Iowa without time for him to firm them up, Independents being assigned to Obama in polls who ended up voting for McCain, strong Clinton organization in NH which makes a bigger diff in a smallish primary like NH, etc).
At most, all of this means just a point or two either way. Obama has a commanding lead. He'll probably get the maximum 2-3 point benefit of field work advantage.
It's all over but the counting.
Posted by Brian | November 3, 2008 4:57 PM