July 3, 2007

Home Broadband Adoption 2007

Methodology and Data

The findings in this data memo are based on the findings of our daily tracking survey on Americans’ use of the Internet conducted by Princeton Survey Research Associates. Most of the data in this report is drawn from the Project’s February-March 2007 survey of 2,200 adult Americans. Of these, 1,492 were internet users and 966 were home broadband users. The margin of error for results based on all such respondents is +/-2.3 percentage points; for internet users it is +/-2.8 percentage points; for home broadband users it is +/-3.5 percentage points.

The number of African-Americans surveyed in February-March 2007 came to 190; 111 were internet users, and 71 were home broadband users. For whites, 1,740 respondents were interviewed, with 1,199 internet users and 767 home broadband users.

For African-Americans, the margin of error for results based on all such respondents is +/-7.8 percentage points; for internet users it is +/-10.2 percentage points; for home broadband users it is +/-12.8 percentage points.

For white Americans, the margin of error for results based on all such respondents is +/-2.5 percentage points; for internet users it is +/-3.1 percentage points; for home broadband users it is +/-3.9 percentage points.

The number of rural Americans surveyed in February-March 2007 came to 447, with 258 rural internet users and 133 rural home broadband users. For residents of urban America, 597 respondents were interviewed, with 422 internet users and 297 home broadband users. The total number of suburban Americans interviewed was 1,156, with 812 internet users and 536 home broadband users.

For rural Americans, the margin of error for results based on all such respondents is +/-5.1 percentage points; for internet users it is +/-6..7 percentage points; for home broadband users it is +/-9.3 percentage points.

For urban Americans, the margin of error for results based on all such respondents is +/-4.4 percentage points; for internet users it is +/-5.2 percentage points; for home broadband users it is +/-6.3 percentage points.

For suburban Americans, the margin of error for results based on all such respondents is +/-3.2 percentage points; for internet users it is +/-3.8 percentage points; for home broadband users it is +/-4.7 percentage points.

For the definition of community type, we follow the Census Bureau definition whereby respondents are categorized as “rural” if they reside in a non-metropolitan statistical area (MSA) county. Respondents are categorized as “suburban” if they reside in any portion of an MSA county that is not in a central city. Respondents are categorized as “urban” if they reside within a central city of an MSA.

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. The sample was released in replicates, which are representative subsamples of the larger population. This ensures that complete call procedures were followed for the entire sample.  At least 10 attempts were made to complete an interview at sampled households. The calls were staggered over times of day and days of the week to maximize the chances of making contact with a potential respondent. Each household received at least one daytime call in an attempt to find someone at home.  In each contacted household, interviewers asked to speak with the youngest male currently at home. If no male was available, interviewers asked to speak with the youngest female at home. This systematic respondent selection technique has been shown to produce samples that closely mirror the population in terms of age and gender.  All interviews completed on any given day were considered to be the final sample for that day.

PSRAI calculates a response rate as the product of three individual rates:  the contact rate, the cooperation rate, and the completion rate.  Of the residential numbers in the sample, 76% were contacted by an interviewer and 41% agreed to participate in the survey.  Eighty-seven percent were found eligible for the interview.  Furthermore, 94% of eligible respondents completed the interview.  Therefore, the final response rate is 29%.

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 March 2006 Annual Social and Economic Supplement. 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.