How the AP-Univision poll was conducted

The Associated Press-Univision poll of Hispanic adults was conducted by the National Opinion Research Center (NORC) at the University of Chicago from March 11-June 3. It is based on a nationally representative random sample of 1,521 Hispanic adults. Data were gathered via mail, the Internet and telephone. The majority of interviews were completed via mail (82 percent); 15 percent were completed by via telephone and four percent via the Internet.

The sponsors and funders of the project include The Associated Press, Univision Communications Inc., The Nielsen Company and Stanford University. Stanford University's participation was made possible by a grant from The Bill & Melinda Gates Foundation.

Fifty-three percent of interviews were conducted in English and 47 percent were done in Spanish.

All respondents were offered a monetary incentive to complete the study.

The probability sample of Hispanic households was provided by The Nielsen Company. Nielsen conducts an annual survey of Hispanic households in the United States for its television viewing ratings services. The sample frame for this survey incorporated 3,427 households that were previously contacted by Nielsen and estimated to be Hispanic.

The response rate for the original Nielsen survey is estimated to be 90 percent. The cumulative response rate for the AP-Univision survey was estimated to be approximately 40 percent.

The final sample was statistically adjusted to be a more accurate representation of all Hispanic householders in the United States based on geography and Hispanic residential penetration, educational attainment and language usage by the householder, as well as the householder's age, sex and country of origin.

No more than 1 time in 20 should chance variations in the sample cause the results to vary by more than plus or minus 3.5 percentage points from the answers that would be obtained if all Hispanics in the U.S. were polled.

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

The questions and results for this poll are available at http://surveys.ap.org.