Research DesignBack

This was a random telephone survey conducted by telephone interviewers under close supervision. All data were collected by our interviewers using a Web-based Computer Assisted Telephone Interview (Web-CATI) system 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.

To minimize sampling bias, 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 this survey was Hong Kong residents aged 18 or above who speak Cantonese. If more than one subject had been available, selection was made using the “next birthday rule” which selected the person who had his/her birthday next. Telephone interviews were conducted during the period of 25 to 31 August, 2015. A total of 1,009 qualified respondents were successfully interviewed. As shown in the calculation of Appendix I, the overall response rate of this survey was 66.3% (Table 2), 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 3.1 percentage points at 95% confidence level.

To ensure representativeness of the findings, the raw data collected 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 2014 year-end and the educational attainment (highest level attended) distribution collected in the 2011 Census. All figures in this report are based on the weighted sample.