Contact InformationBack

Date of survey	:	3 - 7 November 2009
Survey method	:	Telephone survey with interviewers
Target population	:	Cantonese-speaking population of Hong Kong of age 18 or above
Sampling method	:	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.
Sample size	:	1,013 successful cases
Effective Response rate	:	72.3%
Std. sampling error	:	Less than 1.6 percentage points. In other words, the sampling error for all percentages was less than plus/minus 3.1 percentage points at 95% confidence level.

Table 1 Breakdown of contact information of the survey

	Frequency		Percentage
Respondents' ineligibility confirmed		7,108		44.0
Fax/data line	779		4.8
Invalid number	5,381		33.3
Call-forwarding/mobile/pager number	113		0.7
Non-residential number	771		4.8
Special technological circumstances	34		0.2
No eligible respondents	30		0.2

Respondents' eligibility not confirmed		3,543		21.9
Line busy	335		2.1
No answer	2,400		14.9
Answering device	82		0.5
Call-blocking	78		0.5
Language problem	320		2.0
Interview terminated before the screening question	320		2.0
Others	8		0.0

Respondents' eligibility confirmed, but failed to complete the interview		4,486		27.8
Household-level refusal	8		0.0
Known respondent refusal	16		0.1
Appointment date beyond the end of the fieldwork period	4383		27.1
Partial interview	45		0.3
Miscellaneous	34		0.2

Successful cases		1,013		6.3

Total		16,150		100.0

Table 2 Calculation of overall response rate

Overall response rate
= Successful cases / (Successful cases + Refusal cases^ + Incomplete cases*)
= 1,013 / (1,013 + (45 + 320) + (8 + 16))
= 72.3%

^ Including 「household-level refusal」 and 「known respondent refusal」
* Including 「partial interview」 and 「interview terminated before the screening question」