Design of the Influential Americans Survey Sample
The results of the Opinion Leaders survey are based on Americans who are influential in their chosen field. The sample was designed to represent these Influentials in ten professional areas of expertise: media; business and finance; foreign affairs; defense; state and local government; think tanks and academia; religious organizations; science and engineering; labor; and Congressional staff. Every effort was made to make the sample as representative of the leadership of each particular field as possible. However, because the goal of the survey was to identify people of particular power or influence, the sampling was purposive in overall design, but systematic with regard to respondent selection wherever possible.
The final selected sample was drawn from ten subsamples. Subsamples were split into replicates and quotas were set for number of completed interviews from each subsample. These quotas were set because the size of the sampling frame for each subsample varied a great deal. In order to ensure adequate representation of the smaller groups in the final sample of complete interviews it was necessary to set quotas. The subsamples and final completed interviews for each are listed below:
COMPLETED SUBSAMPLE INTERVIEWS
- Media 73
- Business and Finance 35
- Foreign Affairs 69
- Security 57
- Governors and Mayors 75
- Think Tanks and Academics 93
- Religious Leaders 36
- Science and Engineering 92
- Labor Union 24
- Congressional staff 37
The specific sampling procedures for each subsample are outlined below.
The media sample included people from all types of media: newspapers, magazines, television and radio. Various editors (editors, editors of the editorial page, managing editors) and DC bureau chiefs were selected from: the top daily newspapers (based on circulation); additional newspapers selected to round out the geographic representation of the sample; news services; and different types of magazines including news, literary, political, and entertainment and cultural magazines.
For the television sample, people such as DC bureau chiefs, news directors or news editors, anchors, news executives, and executive producers were selected from television networks, chains and news services.
The radio sample included news directors and/or DC bureau chiefs at several top radio stations.
Top columnists listed in the National Journal’s Capital Source and the News Media Yellow Book were also selected as part of the media subsample.
In each part of the media subsample it is possible that more than one individual at an organization was interviewed.
II. Business and Financial
The Business and Financial sample selected Chief Executive Officers from businesses on the Fortune 1000 list of industry and service companies. The business part of the sample was a random selection of businesses in industry and manufacturing. The financial sample was drawn from companies in commercial banking, diversified financial, and savings and loans.
III. Foreign Affairs
The Foreign Affairs sample was randomly selected from the membership roster of the Council on Foreign Relations.
The Security sample was randomly selected from the list of American members of the International Institute for Strategic Studies.
V. State and Local Government
Governors of the 50 states were drawn for the sample, as well as a random sample of mayors of cities with a population of 80,000 or more.
VI. Think Tanks and Academics
The heads of various influential think tanks listed in The Capitol Source were selected. For the academic sample, officers (President, Provost, Vice-President, Dean of the Faculty) of the most competitive schools overall and the most competitive state schools (as identified in a college directory) in the United States were selected.
For the religion sample, religious bodies with membership over 700,000 each were identified as Protestants, Catholics, Jews and Muslims. Top U.S. figures in each national organization were selected in addition to the top people at the National Council of Churches.
VIII. Science and Engineering
The science sample was a random sample of scientists drawn from the membership of the National Academy of Sciences.
The engineering sample was a random sample of engineers drawn from the membership of the National Academy of Engineers.
IX. Labor Unions
The Labor Union sample consisted of top national officers in the 50 largest national unions (based on membership as listed in the 1997 World Almanac).
X. Congressional Policy Staff
The Congressional Policy Staff group was comprised of staffers in both the House and the Senate who work for either: a committee which deals with foreign affairs, defense, or intelligence; or a Member who holds influence on these issues either by dint of leadership position or seniority on a relevant committee. The sample broadly reflected the current partisan breakdown of the Congress.
Each person sampled for this survey was mailed an advance letter on The Pew Research Center for The People and The Press letterhead and signed by Andrew Kohut, Director of the Center. These letters were intended to introduce the survey to prospective respondents, describe the nature and purpose of the survey and encourage participation in the survey. Approximately one week after the letter was mailed specially trained interviewers began calling the individual sample members to conduct the survey or set up appointments to conduct the survey at a later date.
Interviewers for this survey were experienced, executive interviewers specially trained to ensure their familiarity with the questionnaire and their professionalism in dealing with professionals of this level. The interviewing was conducted from July 7, 1997 through September 23, 1997.
About The Public Survey
Results for the main general public survey are based on telephone interviews conducted under the direction of Princeton Survey Research Associates among a nationwide sample of 2,000 adults, 18 years of age or older, during the period September 4-11, 1997. For results 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 2 percentage points. For results based on either Form 1 (N=1007) or Form 2 (N=993), the sampling error is plus or minus 4 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.
Survey Methodology in Detail
The sample for this survey is a random digit sample of telephone numbers selected from telephone exchanges in the continental United States. The random digit aspect of the sample is used to avoid “listing” bias and provides representation of both listed and unlisted numbers (including not-yet-listed). The design of the sample ensures this representation by random generation of the last two digits of telephone numbers selected on the basis of their area code, telephone exchange, and bank number.
The telephone exchanges were selected with probabilities proportional to their size. The first eight digits of the sampled telephone numbers (area code, telephone exchange, bank number) were selected to be proportionally stratified by county and by telephone exchange within county. That is, the number of telephone numbers randomly sampled from within a given county is proportional to that county’s share of telephone numbers in the U.S. Only working banks of telephone numbers are selected. A working bank is defined as 100 contiguous telephone numbers containing three or more residential listings.
The sample was released for interviewing in replicates. Using replicates to control the release of sample to the field ensures that the complete call procedures are followed for the entire sample. The use of replicates also ensures that the regional distribution of numbers called is appropriate. Again, this works to increase the representativeness of the sample.
At least four attempts were made to complete an interview at every sampled telephone number. The calls were staggered over times of day and days of the week to maximize the chances of making a contact with a potential respondent. All interview breakoffs and refusals were re-contacted at least once in order to attempt to convert them to completed interviews. In each contacted household, interviewers asked to speak with the “youngest male 18 or older who is at home”. If there is no eligible man at home, interviewers asked to speak with “the oldest woman 18 or older who lives in the household”. This systematic respondent selection technique has been shown empirically to produce samples that closely mirror the population in terms of age and gender.
Non-response in telephone interview surveys produces some known biases in survey-derived estimates because participation tends to vary for different subgroups of the population, and these subgroups are likely to vary also on questions of substantive interest. In order to compensate for these known biases, the sample data are weighted in analysis.
The demographic weighting parameters are derived from a special analysis of the most recently available Census Bureau’s Current Population Survey (March 1996). This analysis produced population parameters for the demographic characteristics of households with adults 18 or older, which are then compared with the sample characteristics to construct sample weights. The analysis only included households in the continental United States that contain a telephone.
The weights are derived using an iterative technique that simultaneously balances the distributions of all weighting parameters.