Contact Information返回

Date of survey	:	28 - 31 July,2008
Survey method	:	Telephone survey with interviewers
Target population	:	Hong Kong working population of age 18 or above
Sampling method	:	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.
Sample size	:	1,003 successful cases
Effective Response rate	:	75.9%
Std. sampling error	:	Less than 1.6%

Table 1 Breakdown of contact information of the survey

	Frequency	Percentage
Respondents' ineligibility confirmed	1,153	16.3
Fax/ data line	75	1.1
Invalid number	609	8.6
Call-forwarding/ mobile/ pager number	75	1.1
Non-residential number	82	1.2
Special technological difficulties	15	0.2
No eligible respondents	297	4.2

Respondents' eligibility not confirmed	2,058	29.1
Line busy	87	1.2
No answer	1,338	18.9
Answering device	20	0.3
Call-blocking	11	0.2
Language problem	84	1.2
Interview terminated before the screening question	382	5.4
Others	136	1.9

Respondents' eligibility confirmed, but failed to complete the interview	2,861	40.4
Household-level refusal	3	0.0
Known respondent refusal	3	0.0
Appointment date beyond the end of the fieldwork period	2522	35.6
Partial interview	17	0.2
Miscellaneous	316	4.5

Successful cases	1,003	14.2

Total	7,075	100.0

Table 2 Calculation of effective response rate

Effective Response rate
= Successful cases / (Successful cases + Incomplete cases + Refusal cases + Estimated refusal cases of eligible respondents*)
= 1,003 / 1,003 + 17 + 3 + 3 + 382[(1,003 + 17 + 3 + 3) / (1,003 + 17 + 3 + 3 + 297)]*
= 75.9%

*Figure obtained by prorata