Results for the national survey are based on telephone interviews conducted under the direction of Schulman, Ronca, & Bucuvalas, Inc. among a nationwide sample of 1,399 adults, 18 years of age or older, from November 20-26, 2007. For results based on the total sample, one can say with 95% confidence that the error attributable to sampling is plus or minus 3 percentage points. For results based on likely Republican primary voters (N=448), the error attributable to sampling is plus or minus 5.5 percentage points.

Results for the state surveys are based on telephone interviews with a sample of 5,462 adults living in Iowa, New Hampshire, and South Carolina, conducted by Princeton Data Source, LLC under the direction of Princeton Survey Research International, from November 7-25, 2007.

The Iowa survey interviewed a total of 2,111 registered voters, including 264 who say they will definitely or probably attend a Republican caucus. The margin of error for those likely to attend a Republican caucus is +-7%.

The New Hampshire survey interviewed a total of 1,300 registered voters, including 446 who plan to vote in the Republican primary. The margin of error for those who plan to vote in the Republican primary is +-5.5%.

The South Carolina survey interviewed a total of 1,200 registered voters, including 468 who plan to vote in the Republican primary. The margin of error for those who plan to vote in the Republican primary is +-5.5%.

In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls.

About the Center

The Pew Research Center for the People & the Press is an independent opinion research group that studies attitudes toward the press, politics and public policy issues. We are sponsored by The Pew Charitable Trusts and are one of eight projects that make up the Pew Research Center, a nonpartisan "fact tank" that provides information on the issues, attitudes and trends shaping America and the world.

The Center's purpose is to serve as a forum for ideas on the media and public policy through public opinion research. In this role it serves as an important information resource for political leaders, journalists, scholars, and public interest organizations. All of our current survey results are made available free of charge.

All of the Center's research and reports are collaborative products based on the input and analysis of the entire Center staff consisting of:

Andrew Kohut, Director
Scott Keeter, Director of Survey Research
Carroll Doherty and Michael Dimock, Associate Directors
Richard Wike and Kim Parker, Senior Researchers
April Clark, Juliana Menasce Horowitz, Robert Suls and Shawn Neidorf, Research Associates
James Albrittain, Executive Assistant
Alec Tyson, Research Assistant