Exit Polls Overestimated Obama's Strength In 18 Of 20 States Says Report

Citing overstated support for presidential candidate Barack Obama because of the zealousness of his supporters, media channels are worried that Election data they have compiled may present a false image of the Senator's popularity.

The Politico reports polling analyst Mark Blumenthal found exit polling results overestimated the robustness of Barack Obama's campaign during the Democratic primaries earlier this year.
Portions of the leaked report said, during the Democratic primaries this year, preliminary exit polls overestimated Obama's strength in 18 of 20 states, by an average error of 7 percentage points, based on leaked early results. The study found that supporters of Barack Obama were more likely to participate in exit polls.

Insurgent candidate Pat Buchanan’s support also was overstated in the 1992 New Hampshire Republican primary, a phenomenon attributed to the greater willingness of his impassioned supporters to participate in exit surveys.

More recently, in 2004, exit poll data that began circulating early in the afternoon led to short-lived Democratic elation and deep Republican anxiety. By evening, some of President George W. Bush’s key strategists were frantic, emailing reporters at polling organizations to better understand the gap between what they were finding on their own and what the leaked exit polls indicated.

As it turned out, preliminary exit polls overstated women’s turnout that year. This “programming error,” which affects the statistical method that pollsters use to match surveys to the electorate’s composition, was discovered by the third wave of exit polling.

Accurate sampling, however, is an even greater concern. In 2004, the over-sampling of women—who are more likely to be Democrats—was not the only error. Democrats, in general, turned out to be more likely to participate in the exit poll interviews than Republicans.

It also surfaced that younger interviewers, who hand out the paper questionnaire to voters, were less likely to get a response from older voters. Older voters are more likely Republican.

Polling is a very inexact science. Exit polling during the last presidential election indicated that John eFFin Kerry was going to be president in 2004. Just remember, Eighty-Four Percent Say They'd Never Lie To A Pollster says Ann Coulter.