Attachment 8.KNrecruitmethods 4-24-2007

Attachment 8

Knowledge Networks Panel Recruitment Methodology

Panel Recruitment Methodology

Knowledge Networks (KN) uses list-assisted random-digit-dial (RDD) sampling techniques on the sample frame consisting of the entire U.S. telephone population. The sample frame is updated quarterly. KN excludes only those banks of telephone numbers (consisting of 100 telephone numbers) that have zero directory-listed phone numbers. KN’s telephone numbers are selected from the 1+ banks with equal probability of selection for each number. Note that the sampling is done without replacement to ensure that numbers already fielded by KN do not get fielded again.

Having generated the initial list of telephone numbers, the sample preparation system excludes confirmed disconnected and nonresidential telephone numbers. Next, the sample is screened to exclude numbers that are not in the WebTV Internet Service Provider network. This process results in the exclusion of approximately 6% to 8% of the U.S. population. Because this percentage diminished steadily since July 2001, KN now includes a small sample from the out of WebTV Internet Service Provider network in the panel to represent these areas and reduce coverage error.

Telephone numbers for which KN is able to recover a valid postal address (about 50%) are sent an advance mailing informing them that they have been selected to participate in the KN Panel. In addition to information about the KN Panel, the advance mailing also contains a monetary incentive to encourage cooperation when the interviewer calls. Following the mailing, the telephone recruitment process begins. The numbers called by interviewers consist of all numbers sent an advance mailing, as well as 50% of the numbers not sent an advance mailing. Cases sent to telephone interviewers are dialed up to 90 days, with at least 15 dial attempts on cases where no one answers the phone and 25 dial attempts on phone numbers known to be associated with households. Refusal conversion procedures are also performed, including callbacks to reiterate the importance of the study and the availability of study incentives.

Experienced interviewers conduct all recruitment interviews. An interview, which typically requires about 10 minutes, begins with the interviewer informing the household member that they have been selected to join the KN Panel. They are told that in return for completing a short survey weekly, the household will be given a WebTV set-top box and free monthly Internet access. All members in the household are then enumerated, and some initial demographic variables and background information of previous computer and Internet use are collected.

Households already having Internet access are permitted to use their own Internet-connected computers for self-administration of interviews. In contrast, each non-Internet household is provided with identical hardware for survey administration. Microsoft’s WebTV is the hardware platform currently used by the KN Panel. The device consists of a set-top box that connects to a TV and the telephone. It also includes a remote keyboard and pointing device. WebTV has a built-in 56K modem that provides the household with a connection to the Internet. The base unit also has a small hard drive to accommodate large file downloads, including video files. File downloads do not require any user intervention and usually occur during off hours.

Prior to shipment, each unit is custom configured with individual e-mail accounts, so that it is ready for immediate use by the household. Most households are able to install the hardware without additional assistance, although KN maintains a telephone technical support line and will, when needed, provide on-site installation. The KN Call Center also contacts household members who do not respond to e-mail and attempts to restore contact and cooperation.

All new panel members are sent an initial survey to confirm equipment installation and familiarize them with the WebTV unit. Demographic information, such as gender, age, race, income, and education, are collected for each participant to create a member profile. This information can be used to determine eligibility for specific studies and need not be gathered with each survey. Starting in August 2002, KN began oversampling households that had preexisting, home-based Internet access, allowing these households to participate in the Web-enabled panel using their own equipment and Internet access. These panel members are enrolled into a panel loyalty program intended to encourage long-term participation in the research panel. Currently, the KN panel consists of approximately 40,000 participants.

E-mail List Sample Recruitment

Often, a probability-based sample alone is not sufficient or large enough to reach a desired subpopulation of interest. The target audience for HTMSC is particularly narrowly defined. Because the available sample pool from the KN panel is not expected to provide enough sample to sufficiently power the study, national nonprobability-based e-mail list samples obtained from SSI and/or GHI will be used to boost the study’s sample size. The advantage to this approach is that it provides a representative base of the U.S. population (the KN panel), allowing data from the panel to be analyzed separately or jointly with augment samples from other sources. This provides a basis upon which to validate the overall sample and investigate and control for potential biases.

When requesting the e-mail list sample, KN will specify the demographic information of potential respondents (age, gender, marital status, race, and education). A sample of the e-mail list will be drawn and then potential respondents will be sent an e-mail invitation to participate in the study. Potential respondents will be given a user ID that they will be required to enter to access the study’s website. After entering their ID, each potential respondent will be given a description of the study topic and will be asked whether they agree to answer the screener questions to determine their eligibility to participate in the study. Potential participants who agree will be administered the online screener. Individuals who are eligible for the study will be presented the more detailed online consent form. Potential participants will formally consent or decline to participate by clicking links in their Web browsers that indicate either agreement or disagreement to participate.