Efforts to Ensure Quality Participation. Westat used commercially available lists of phone numbers and addresses of owners and renters for the Washington, DC area and all of the COLA areas, except Guam, Puerto Rico, and the U.S. Virgin Islands for which such lists were unavailable. Using the sampling strategy described in Section 3.2, Westat drew the sample using commercial data bases where available. Westat then mailed letters to the prospective respondents informing them of the survey and asking for their cooperation. The letter was prepared by OPM on OPM letterhead and signed by Xxxxxx X. Xxxxxxxx, who at that time was OPM’s Deputy Associate Director for Pay and Performance Policy, Strategic Human Resources Policy Division. For those areas where commercial mailing/phone lists were unavailable, Westat was unable to mail advance letters; and Westat used simple random sampling to select potential participants. At the beginning of each telephone interview, Westat surveyors explained the purpose of the survey, that the survey was voluntary, and provided the respondent the OMB-provided information collection number. Westat made certain that the respondent was a knowledgeable adult who could answer questions relating to the housing unit. If the adult was not available, Westat made arrangements to call back at a more convenient time to conduct the interview. The complete interview took approximately 8 minutes. It was critically important that GPRES collect accurate information from persons who either owned their own homes or rented homes at current market rents. To this end, some GPRES questions were designed to eliminate respondents who did not meet these criteria. For example, Westat discontinued the survey if the respondent lived in rent-subsidized or rent-controlled housing, occupied military housing, or rented from relatives or other persons at rates other than market rates. Likewise, Westat discontinued the survey if the respondent was renting a room in a home or was living in a mobile home or similar lodging. In addition, OPM identified for Westat several ‘‘threshold’’ questions that were critical to the survey and instructed Westat to discontinue the survey if the respondent could not or would not answer these questions. For example, if the respondent did not know or refused to answer how many bathrooms or bedrooms were in the home, Westat was instructed to discontinue the survey. The questionnaire in Appendix A shows the threshold questions. They are identified by the interview instruction ‘‘...
