Target respondents of the study were Cantonese-speaking population of Hong Kong of age 18 or above. Telephone interviews were conducted by interviewers under close supervision. To minimize sampling bias, telephone numbers were first drawn randomly from the residential telephone directories as 「seed numbers」, from which another set of numbers was generated using the 「plus/minus one/two」 method, in order to capture the unlisted numbers. Duplicated numbers were then filtered, and the remaining numbers were mixed in random order to produce the final telephone sample. When telephone contact was successfully established with a target household, one person of age 18 or above was selected. If more than one qualified subject had been available, selection was made using the 「next birthday rule」 which selected the person who had his/her birthday next from all those present.
This year's survey was conducted during the period of 3 to 7 November 2009. A total of 1,013 qualified respondents were successfully interviewed. The overall response rate was 72.3% and the standard error due to sampling was no more than 1.6 percentage points. That means at 95% confidence level, the sampling error of percentage figures was less than plus/minus 3.1 percentage points. Please refer to Tables 1 and 2 in Appendix I.
All data were collected by our interviewers using a Computer Assisted Telephone Interview (CATI) system which allowed real-time data capture and consolidation. To ensure data quality, on top of on-site supervision, voice recording, screen capturing and camera surveillance were also used to monitor the interviewers' performance.
The data collected have been adjusted according to provisional figures obtained from the Census and Statistics Department regarding the gender-age distribution of the Hong Kong population in mid-2009. All analyses in this report are based on the weighted data.