Associated Press-GfK poll on the price of gasoline was conducted by GfK Roper public affairs & Corporate Communications from 5 to 9 May. It is based on landline and cellular telephone interviews with a representative random sample of 1,001 adults. Interviews with the 700 respondents on fixed phones and 301 on cell phones.
Numbers in compound telephone numbers were generated randomly to reach households with sides and listed landline and cell phone numbers.
Interviews in English and Spanish.
As is commonly done in surveys, results have been weighted, or adjusted to ensure that the answers reflect make-up of the population by factors such as age, sex, education and race. In addition, the weighting took into patterns of use of the telephone - only fixed, only cell and two types - by region.
Should not more than 1 times in 20 variations of chance in the sample cause the results vary by superior more or less 4.2 percentage points of the responses that would be obtained if all the United States adults were interviewed.
There are other sources of potential error in the polls, including the text and the order of the questions.
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