Telephone interviews were conducted by interviewers under close supervision. 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 used to monitor the interviewers' performance.
The target population of this survey is Cantonese speaking HK citizens of age between 18 and 60 year old who own at least one computer or mobile device and living with at least one other family members. If more than one eligible subject had been available, the one who had his/her birthday next was selected.
The survey was conducted during the period of January 14 to 21, 2013. 517 respondents were successfully interviewed. The effective response rate was 74.6%, and the standard sampling error for percentages based on this sample was less than 2.2 percentage points. In other words, the maximum sampling error for percentages was less than plus/minus 4.4 percentage points at 95% confidence level.