Three big questions about the accuracy of polling regularly resurface during the 2008 campaign, according to Mark Blumenthal at Pollster.com. Expect to hear more about each of these in the weeks ahead.
1. Will the growth of the "cell-phone-only" voter bias polls against Obama? Most surveys sample using land line random digit dialing methods. The number of cell-phone-only users has tripled since 2004, meaning many polls may miss a significant (and disproportionately younger) group of voters.
2. Will the Wilder/Bradley effect reemerge? This theory argues voters find it "socially unacceptable" to tell pollsters they will vote for the white candidate running against a black candidate. Wilder refers to former Virginia governor Doug Wilder's race in 1989, and Bradley refers to the former Los Angeles mayor's election in 1982. In both cases, support for their white opponents on Election Day exceeded pre-election polls.
3. Will the "likely voter models" misrepresent the electorate due to the surge in new registrants?
Blumenthal writes that the three issues could impact polls, but with offsetting effects:
Meanwhile, we can probably dispense with the "Perfect Storm" analogy. In the movie of the same name, three different weather-related phenomena combined to produce a storm of exceptional severity. In this case, as Democratic strategist Joe Trippi pointed out in September, the potential polling foibles may work in opposite directions and "cancel each other out." A return of the Bradley-Wilder effect would work to McCain's benefit, while an underrepresentation of younger, African American or "cell-phone-only" voters will likely benefit Obama.
Read Blumenthal's entire piece here.