The AP-Knowledge Networks Poll is a unique study to find out how the electorate's political views have changed since last election.
This study included 1,254 adults on Sept. 17 to Oct. 7 were originally part of a random sample of Americans surveyed up to 11 times throughout the 2008 campaign by The Associated Press, Knowledge Networks and Yahoo News.
The extensive national survey was conducted by Knowledge Networks of Menlo Park, Calif., under the direction and supervision of The Associated Press' polling unit.
Interviews were conducted online. The original sample was drawn from a panel of respondents Knowledge Networks recruited via random sampling of landline telephone households with listed and unlisted numbers. The company provides Web access to panel recruits who don't already have it. With a probability basis and coverage of people who otherwise couldn't access the Internet, the Knowledge Networks online surveys are nationally representative.
Results were weighted, or adjusted, to reflect the adult population by demographic factors such as age, sex, region, race, and education.
No more than one time in 20 should chance variations in the sample cause results to vary more than plus or minus 4.4 percentage points from the answers that would have been obtained if all adults in the U.S. were surveyed. The longitudinal nature of the study could contribute to additional sources of error.
There are other, potentially greater, sources of variability in surveys, including the wording and order of the questions.
The questions and results for this poll are available at http://surveys.ap.org.