About this Survey and its Methodology

The survey results are based on 2,113 telephone interviews conducted under the direction of Princeton Survey Research Associates from a nationwide sample of the voting age population, from Wednesday evening, Oct. 30, through Saturday evening, Nov.2, 2002. For results based on the total sample (N=2,113), there is 95% confidence that the error attributed to sampling and other random effects is +/- 2.5 percentage points. For results based on registered voters (N=1,610), the sampling error is +/- 3 percentage points, and for results based on likely voters (N=1,035), the sampling error is +/- 3.5 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.

The sample for this survey is a random digit sample of telephone numbers selected from telephone exchanges in the continental United States. The exchanges were selected with probabilities proportional to their size, with the first eight digits of the numbers selected to be proportionally stratified by county and by exchange within county.

At least four attempts were made to complete an interview at every sampled number, with calls staggered to maximize the chances of reaching a potential respondent. Non-response in telephone interview surveys produces some known biases in survey-derived estimates. To compensate, the sample data are weighted in analysis using parameters derived from a special analysis of the most recently available Census Current Population Survey.