Results for the survey are based on telephone interviews conducted under the direction of Princeton Survey Research Associates among a nationwide sample of 1,703 adults, 18 years of age or older, during the period March 17-21, 2004. Based on the total sample, one can say with 95% confidence that the error attributable to sampling and other random effects is plus or minus 3 percentage points. For results based on either Form 1 (N=864) or Form 2 (N=839), the sampling error is plus or minus 4 percentage points. For results based on Registered Voters (N=1306), the sampling error is plus or minus 3 percentage points.
Results for public attention to Richard Clarke’s claims that the president ignored serious warnings prior to the Sept 11 terrorist attacks are from a separate survey of 1,065 adults, 18 years of age or older, during the period March 22-24, 2004. Based on the total sample, one can say with 95% confidence that the error attributable to sampling and other random effects is plus or minus 3.5 percentage points. Data from the March 22-24 survey are unweighted.
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.
