Contact information
 

  Date of survey : 18-29 January, 2008
  Survey method : Telephone survey with interviewers
  Target population : Local working population aged 18 to 65 with a minimum monthly personal income of HK$5,000 and being covered by an MPF scheme.
  Sampling method :
The contacts 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.
  Sample size : 505 successful cases
  Overall Response rate : 81.7%
  Std. sampling error : Less than 2.2 percentage points. In other words, the sampling error for all percentages was less than plus/minus 4.4 percentage points at 95% confidence level.

Table 1 Calculation of effective response rate

   Overall Response rate
= [ Successful cases / (Successful cases + Partial interview + Refusal cases by eligible respondents + Refusal cases by prorated-eligible respondents) ]
= [ 505 / (505 + 6+ 9 + 238[(505 + 6+ 9) / (505 + 6+ 9+ 737)]* ) ]
= 81.7%
*Figure obtained by prorata

Table 2 Breakdown of contact information of the survey

 

Frequency

Percentage

Respondents’ ineligibility confirmed

5,532

46.6%

Fax/ data line

684

5.8%

Invalid number

3,499

29.5%

Call-forwarding/ mobile/ pager number

48

0.4%

Non-residential number

488

4.1%

Special technological difficulties

76

0.6%

No eligible respondents

737

6.2%

Respondents’ eligibility not confirmed

2,711

22.8%

Line busy

156

1.3%

No answer

1,974

16.6%

Answering device

68

0.6%

Call-blocking

49

0.4%

Language problem

158

1.3%

Interview terminated before the screening question

238

2.0%

Others

68

0.6%

Respondents’ eligibility confirmed, but failed to complete the interview

3,119

26.3%

Household-level refusal

6

0.1%

Known respondent refusal

3

0.0%

Appointment date beyond the end of the fieldwork period

2,733

23.0%

Partial interview

6

0.1%

Miscellaneous

371

3.1%

Successful cases

505

4.3%

Total

11,867

100.0%



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