Telephone interviews were conducted by telephone interviewers under close supervision. All data were collected by interviewers using a Web-based Computer Assisted Telephone Interview (Web-CATI) system invented in-house by the research team, which allowed real-time data capture and consolidation. To ensure data quality, on top of on-site supervision and random checking, voice recording, screen capturing and camera surveillance were used to monitor the interviewers’ performance.
Telephone numbers were randomly generated using known prefixes assigned to telecommunication services providers under the Numbering Plan provided by the Office of the Communications Authority (OFCA). Invalid numbers were then eliminated according to computer and manual dialing records to produce the final sample.
The target population of the survey was Hong Kong residents aged 18 or above who spoke Cantonese. After telephone contact was successfully established with a target household, one eligible person was selected using “next birthday rule” for the interview. Telephone interviews were conducted during the period of 12 to 15 December, 2016. A total of 1,003 Hong Kong residents of age 18 or above were successfully interviewed. The response rate of this survey was 71.7%, and the standard sampling error for percentages based on this sample was less than 1.6 percentage points. In other words, the sampling error for all percentages using the total sample was less than plus/minus 3.2 percentage points at 95% confidence level.
To ensure representativeness of the findings, the raw data have been rim-weighted according to provisional figures obtained from the Census and Statistics Department regarding the gender-age distribution of the Hong Kong population in 2016 mid-year and the educational attainment (highest level attended) distribution collected in the 2011 Census.