The Associated Press-GfK Poll on persuadable voters was conducted by GfK Roper Public Affairs & Corporate Communications from Aug. 16-20. It is based on landline and cellphone telephone interviews with a nationally representative random sample of 1,006 adults, including 885 registered voters. Interviews were conducted with 604 respondents on landline telephones and 402 on cellular phones.
Digits in the phone numbers dialed were generated randomly to reach households with unlisted and listed landline and cellphone numbers.
Interviews were conducted in both English and Spanish.
As is done routinely in surveys, results were weighted, or adjusted, to ensure that responses accurately reflect the population's makeup by factors such as age, sex, education and race. In addition, the weighting took into account patterns of phone use — landline only, cell only and both types — by region.
No more than 1 time in 20 should chance variations in the sample cause the results to vary by more than plus or minus 3.9 percentage points from the answers that would be obtained if all adults in the U.S. were polled. The margin of sampling error for registered voters is plus or minus 4.1 percentage points.
There are other sources of potential error in polls, including the wording and order of questions.
The questions and results are available at http://www.ap-gfkpoll.com .