AP-GfK Poll Methodology

The Associated Press-GfK Poll was conducted from January 12 through January 17, 2010, by GfK Roper Public Affairs & Media – a division of GfK Custom Research North America.  This telephone poll is based on a nationally-representative probability sample of 1,008 adults age 18 or older.  The interviews were conducted with 707 respondents on landlines and 301 respondents on cellular telephones.  Both the landline and cell phone samples were provided by Survey Sampling International. The sample included the contiguous 48 states, Alaska, and Hawaii. Interviews were conducted in both English and Spanish, depending on respondent preference.

The combined landline and cell phone data were weighted to account for probabilities of selection, sex, education, and race, using targets from the March 2008 supplement of the Current Population Survey.  In addition to these factors, the weighting takes into account the patterns of land and cell phone usage by region from the 2008 Fall estimates provided by Mediamark Research Inc.

The margin of sampling error is plus or minus 4.4 percentage points at the 95% confidence level, for results based on the entire sample of adults. This margin of error takes into account variability due to weighting.  The margin of sampling error is higher and varies for results based on sub-samples.  In our reporting of the findings, percentage points are rounded off to the nearest whole number.  As a result, percentages in a given table column may total slightly higher or lower than 100%.  In questions that permit multiple responses, columns may total significantly more than 100%, depending on the number of different responses offered by each respondent.

Trend data are displayed for selected questions from previous AP-GfK Polls that also consisted of telephone interviews with nationally-representative probability samples of adults age 18 or older. For more information, contact info@ap-gfkpoll.com.

Please check back for a more detailed methodological description in the coming weeks.