This report is based on a continuous survey of American adults from November 19 through December 23. Some 4,052 American adults (18 and over) were interviewed – 2,364 of them are Internet users. For results based on the total sample, one can say with 95% confidence that the error attributable to samples of both all Americans and Internet-using Americans and other random effects is plus or minus 2 percentage points.
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 numbers). The design of the sample achieves 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.
A new sample was released daily and was kept in the field for at least five days. This insures that the complete call procedures are followed for the entire sample. Additionally, the sample was released in replicates to insure that the telephone numbers called are distributed appropriately across regions of the country. At least 10 attempts were made to complete an interview at every household in the sample. The calls were staggered over times of the day and days of the week to maximize the chances of making contact with a potential respondent. Interview refusals were re-contacted at least once in order to try again to complete an interview. All interviews completed on any given day were considered to be the final sample for that day.
Non-response in telephone interviews produces some known biases in survey-derived estimates because participation tends to vary for different subgroups of the population, and these subgroups are also likely to vary 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 Current Population Survey (September 2001). This analysis produced population parameters for the demographic characteristics of adults age 18 or older, living in the households that contain a telephone. These parameters are then compared with the sample characteristics to construct sample weights. The weights are derived using an iterative technique that simultaneously balances the distribution of all weighting parameters.
Throughout this report, the survey results are used to estimate the approximate number of Americans, in millions, who engage in Internet activities. These figures are derived from the Census Bureau’s estimates of the number of adults living in telephone households in the continental United States. As with all survey results, these figures are estimates. Any given figure could be somewhat larger or smaller, given the margin of sampling error associated with the survey results used in deriving these figures.
About the Pew Internet & American Life Project
The Pew Internet & American Life Project is a non-profit initiative fully funded by The Pew Charitable Trusts. The Project creates original research that explores the impact of the Internet on children, families, communities, health care, schools, the work place, and civic/political life. For more information, please visit our Web site: https://www.pewresearch.org/internet/.
