How the AP-NORC Center poll was conducted

AP News
Posted: Dec 12, 2014 3:40 AM

The Associated Press-NORC Center for Public Affairs Research poll on the environment was conducted by GfK from Nov. 20-Dec. 1.

Funding for the poll came from the Yale School of Forestry and Environmental Studies.

It is based on online interviews of 1,578 adults who are members of GfK's nationally representative KnowledgePanel.

The original sample was drawn from respondents recruited via phone or mail survey methods. GfK provides Internet access to participants who don't already have it. With a probability basis and coverage of people who otherwise couldn't access the Internet, online surveys using KnowledgePanel are nationally representative.

Interviews were conducted in English.

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, race, education and metropolitan status.

No more than 1 time in 20 should chance variations in the sample cause the results to vary by more than plus or minus 2.9 percentage points from the answers that would be obtained if all adults in the U.S. were polled.

There are other sources of potential error in polls, including the wording and order of questions.

The poll had a cooperation rate of 48 percent.

The questions and results are available at .