Trained interviewers called households whose phone numbers were randomly selected by computer. Then, one adult in each household was selected randomly to be interviewed. The results have been weighted to properly balance the sample by age, sex and areas of the county. The poll's margin of error among the 696 likely voters is 3.7 percentage points. This means, in theory, in 19 out of 20 cases the poll results will differ by no more than 3.7 points above or below the results that would have been obtained by questioning all Jefferson County adults who have telephones.
Percentages based on subsamples are subject to a higher potential margin of error.
In addition to these sampling errors, the practical difficulties of conducting any survey can also influence the results.