Notes on Methodology

Harris Interactive conducted 2,862 telephone interviews in the United States among men and women 18 years of age and older, using a random digit dialing technique with a national probability sample. In order to ensure comparability with the in-person Chicago Council studies of 1998 and previous years, personal in-home interviews with a national probability sample of 400 men and women 18 years of age and older were also conducted, using an abridged version of the telephone questionnaire that concentrated on questions repeated from 1998. All interviewing of the general public was conducted between June 1 and June 30, 2002. Data for the telephone and in-person interviews were weighted separately according to known demographic characteristics of the population and merged to form a combined sample (n=3,262).

In order to explore a very extensive set of topics, many questions were asked only of randomly selected subsamples of approximately 700 telephone respondents. “Core” questions, including most of those repeated from 1998, were also asked of the 400 in-person interviewees. Certain key questions were asked of all 2,862 telephone interviewees or all 3,262 respondents.

The margin of sampling error in response frequencies varies negatively with the number of respondents asked a question and positively with the closeness of opinion division. For a fifty-fifty division of opinion (where margins of error are highest), at the p ¡Ü .05 level the margins of error in this study range from 1.7 percentage points (for questions asked of all respondents) up to 4 percentage points (for questions asked of 700 respondents.)

Separate analysis of the telephone and in-person data reveals that, as the literature would predict, there tend to be certain systematic “mode” differences in responses. Telephone interviewees, for example, tend to give fewer “don’t know” responses and to give more “positive” or first-option responses (e.g., more perceptions of vital interests and more ratings of goals as “very important”). This does not mean that either method is incorrect; both meet professional standards and accurately reflect responses by the populations from which they sample. But mode differences do complicate the assessment of opinion changes from the in-person surveys of 1998 and previous years. This report is based on the combined 2002 telephone and in-person data set, which mitigates mode differences. In addition, only those contrasts with previous Council surveys that appear in both the 2002 combined data set and the 2002 in-person interviews taken separately are interpreted in this report as demonstrating opinion changes. An exception is made for the “active part in world affairs” question, for which the in-person responses do not show a significant change from 1998, but the much higher level of activism displayed in the 2,862 telephone responses is confirmed as indicating a real opinion change by others’ surveys conducted in 2002.

Chicago Council surveys have been carried out every four years since 1974. Prior to 2002, all but the first were conducted by the Gallup Organization; Harris conducted the 1974 survey.