2011 Housing Planning Study - Technical Report

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selection system which permits disproportionate sampling by telephone exchange. A similar system has been developed for wireless telephone numbers. The landline sampling frame was stratified by geography comparable to districts selected by each county agency participating in the study. Districts differed from one county to another. There were five districts on the Hawaii Island (Ka'u/South Kona, North Kona, North Hawai i, North and South Hilo, Puna), Oahu (Leeward Oahu, Central Oahu, Windward Oahu, PUC Honolulu, East Honolulu) and Ka'ua'i (Waimea, Koloa, Lihue, Kawaihau, Hanalei). Maui County had the largest number of districts with six on the island of Maui (Nana, Makawao/Pukalani/Kula, Paia/Haiku, Kihei/Makena, Wailuku/Kahului, West Maui) and one each for Molokai and Lanai. The wireless sampling frame was stratified by county only. At the present time, this frame cannot be meaningfully stratified at any lower level. The address associated with each number is taken from the location of the retail company that sold the phone and/or plan being used with each number. Internal survey data are then used to locate the user address according to the same areas noted above. The disproportionate samples were designed to produce equal sampling precision for these districts. The number of households in each district in 2011 was estimated by SMS Research and sample sizes were selected to produce standard errors of the proportion of plus-or-minus five percentage points at the 95 percent confidence level, with p = .50. The sample design is shown in Table 1 on the following page. Interviewer Selection and Training SMS Research was responsible for the selection, training, and supervision of all interviewers assigned to this project. Regardless of background or experience, all interviewers were specially trained to conduct the housing survey interviews. The training session included: a review of general telephone interviewing procedures; a question-by-question review of the survey instrument; on-screen CATI training; and a question-and-answer session to make sure that interviewers had all problems handled before beginning work on the survey. During the fielding of the survey, there were frequent, short debriefing sessions in which interviewers could bring up any additional questions or issues and have them addressed by the project manager. Data Collection Survey data were collected by phone from March through August 2011. All interviews were conducted from the SMS Honolulu Calling Center and separate calling protocols were developed for Iandline and wireless surveys. The Calling Center is equipped with a state-of-the- art computer assisted telephone interviewing (CATI) system that was used for this project. The system provides for rigorous control of sampling, disposition of all calls dialed, and survey administration. It works equally well for Iandline and wireless calling, but the call disposition codes are set differently for each survey type. Calls were placed between the hours of 12:00 PM and 9:00 PM on weekdays and 10:00 AM and 9:00 PM on weekends. An unlimited callback procedure was employed. In practice, some numbers were re-dialed as many as eight times in order to complete interviews. SMS conducted a follow up mailing to areas of Maui County (Nana, Pa'ia-Haiku, West Maui, and Lanai) to supplement areas in which we were able to reach quota for the telephone surveys. Surveying took place during September 2011. A total of 344 surveys were returned from those areas. Hawaii Housing Planning Study,2011: Technical Report Page 7 0 SMS, Inc. November,2011