Methodology

This Pew Internet & American Life Project report is based on the findings of a daily tracking survey on Americans’ use of the Internet. Telephone interviews were conducted by Princeton Survey Research Associates between March 12 and March 19 and then from April 29-May 20, 2003 among a sample of 2,515 adults, 18 and older. 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 Internet users (n=1,555) the margin of sampling error is plus or minus 3 percentage points. In addition to sampling error, question wording and practical difficulties in conducting telephone surveys may introduce some 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 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.

New sample was released daily and was kept in the field for at least five days. This ensures that complete call procedures were followed for the entire sample. Additionally, the sample was released in replicates to make sure 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 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. The overall response rate was 32.8%.

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 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 2002). This analysis produces population parameters for the demographic characteristics of adults age 18 or older, living in 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.

Questionnaire and answers

CONT01  Do you have your own web site?

CONT02          How often do you post material to the site? 

CONT03 Have you ever contributed material to (INSERT)?  (If YES, Have you contributed material to the site in the last three months?)

CONT04  Do you ever visit the web sites of other families or individuals? 

CONT05  Do you use a web cam or web camera to make live pictures appear on a web site? 

CONT06  Do you use the web cam to stream video while conversing with someone else? 

CONT07  Do you write a web diary, web log or blog that is posted online? 

CONT08          How frequently do you update the material on your blog? 

CONT09          Have you ever visited the web diaries or blogs of other people? 

CONT10  Have you ever written or posted material to another person’s blog? 

CONT11 Do you ever visit the web diaries or blogs of (INSERT)?

CONT12 Now I’d like to ask about various types of files people can post online to web sites.  Do you ever post (INSERT) on the Internet?

CONT13  Do you allow others to download files from your computer, such as music or video files? 

CONT14 Do you care whether or not the files you allow others to download from your computer are copyrighted, or isn’t that something you care much about? 

CONT15  Have you ever been to an online newsgroup?

CONT16  Do you ever post your comments to the newsgroup? 

CONT17  Do you post files to the newsgroup such as video, audio or photo files?