Results for the Mid-October 2004 political survey are based on telephone interviews conducted under the direction of Princeton Survey Research Associates International among a nationwide sample of 1,568 adults, 18 years of age or older, during the period October 15-19, 2004. For results based on registered voters (N=1,307) the sampling error is plus or minus 3 percentage points. If based on Form 1 or Form 2 registered voters only (Form 1 N=633 or Form 2 N=674), the sampling error is plus or minus 4.5 percentage points.

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.