Research DesignBack
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1. Survey method
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Data was collected through a random telephone survey conducted by interviewers under close supervision.
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2. Target population and sample size
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The target population of this survey was Cantonese-speaking residents in Hong Kong of age 18 or above. The total sample size of this survey was set at 1,000+ successful interviews with the qualified respondents.
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3. Sampling method
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At the first level of sampling, telephone numbers were first be drawn randomly from residential telephone directories to become "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 be filtered, and the remaining numbers mixed in random order to produce the final telephone sample. At the second level of sampling, when telephone contact was successfully established with a target household, one person qualified was selected from all those present using the "next birthday" rule (i.e. select the member whose birthday is nearest to the interview date).
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4. Fieldwork operation
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Between 16-20 January, 2004, POP deployed a pool of well-trained telephone interviewers to conduct the interviews. All data were collected by interviewers using a Computer Assisted Telephone Interview (CATI) system, which allowed real-time data capture and consolidation. To ensure data quality, voice recording, screen capturing and real-time camera surveillance, on top of on-site supervision, were used to monitor interviewers' performance.
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5. Response rate calculation
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Response rate is calculated as the number of successful cases divided by the sum of successful cases plus effective refusals from confirmed eligible respondents and incomplete cases. Each target telephone number was attempted 5 times before the number was dropped as "busy", "no answer" or "answering device".
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POP's standard formula for calculated response rate is as follows:
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^ Including "household-level refusal" and "known respondent refusal" |
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