6503.0 - Household Expenditure Survey and Survey of Income and Housing: User Guide, 2003-04

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Contents >> Part 2 - Survey Methodology >> 2.2 Selected Samples and Final Samples

2.2 SELECTED SAMPLES AND FINAL SAMPLES

SAMPLE DESIGN

The samples were designed to produce reliable estimates for broad aggregates for households resident in private dwellings aggregated for Australia, for each state and for the capital cities in each state and territory. More detailed estimates should be used with caution, especially for Tasmania, the Northern Territory and the Australian Capital Territory (see 2.8 'Reliability of estimates').

The SIH sample was designed in conjunction with the HES. In the combined sample, some dwellings were selected to complete both the SIH questionnaire and the HES questionnaire, while other dwellings were selected to complete the SIH questionnaire only. Dwellings were selected through a stratified, multistage cluster design from the private dwelling framework of the ABS Population Survey Master Sample. Selections were distributed randomly across a twelve month enumeration period so that the survey results are representative of income and expenditure patterns across the year.

SELECTED DWELLINGS, SAMPLE LOSS AND SELECTED HOUSEHOLDS

In 2003-04, 16,554 dwellings were initially selected for the combined sample. When field work commenced some dwellings selected for inclusion in the HES and SIH samples were found to have no possibility of delivering a survey response. Collectively these are referred to as sample loss, and are composed of the following groups:

dwellings which are out of scope of the surveys; under construction, demolished, or converted to non-private dwellings or non-dwellings
private dwellings which:

In 2003-04 sample loss was 2,067 dwellings, 12.5% of the initially selected sample.

Sometimes dwellings that have been selected for inclusion in a survey are found to comprise more than one actual dwelling because, for example, an additional residence such as a 'granny flat' has been added to the original dwelling. In such cases, each actual dwelling becomes a separate household. Occasionally the residents of a selected dwelling request that their details be provided separately from other dwelling residents, for privacy reasons. In 2003-04, a separate household was created for each such group of residents. In 2003-04, 51 selected dwellings were split into 2 households, 2 into 3, and 1 into 4.

The net result of these activities was that 14,545 households were approached to complete the HES and/or SIH.

RESPONDING HOUSEHOLDS AND FINAL SAMPLE

Households selected for inclusion in the surveys can be categorised as responding or non-responding households. Responding households are either fully responding or partially responding. In the HES and the SIH, information missing from partially responding households is imputed, as described in 2.4 'Data processing'.

Non-responding households include:

households affected by death or illness of a household member
households in which the significant person(s) in the household did not respond because they could not be contacted, had language problems or refused to participate
households in which the significant person(s) did not respond to key questions.

The table 2.2.1 shows the differences between the number of households selected for inclusion in the surveys and the number of responding households included in the final samples.

Table 2.2.1 Selected and responding households

		Households approached	Non-response	Final sample

HES sample (ie included in HES and SIH)		9 753	2 796	6 957
SIH sample
	-included in HES and SIH	9 753	2 425	7 328
	-included in SIH only	4 792	759	4 033
	-Total	14 545	3 184	11 361

Of the 9,753 households initially selected for inclusion in both the HES and the SIH, 6,957 (71%) responded with sufficient information to be included in the final HES and SIH samples and an additional 371 responded with sufficient information to be included in the final SIH sample but not the final HES sample. Of the 4,792 households initially selected for inclusion in the SIH only, 4,033 (84%) responded with sufficient information to be included in the final SIH sample. In aggregate, 11,361 households were included in the final SIH sample, representing an overall response rate of 78%.

Tables 2.2.2 and 2.2.3 show the distribution of the final samples between states and territories and between capital cities and the balance of state.

Table 2.2.2 FINAL NUMBER OF HOUSEHOLDS IN HES AND SIH SAMPLES

	Capital City		Balance of state		Total
	HES	SIH	HES	SIH	HES	SIH
	no.	no.	no.	no.	no.	no.

NSW	1 199	1 537	545	1 093	1 744	2 630
Vic.	1 087	1 690	445	696	1 532	2 386
Qld	579	845	308	1 151	887	1 996
SA	581	890	283	367	864	1 257
WA	475	950	254	490	729	1 440
Tas.	416	423	139	400	555	823
NT	301	335	76	87	377	422
ACT	269	407	. .	. .	269	407
Aust.	4 907	7 077	2 050	4 284	6 957	11 361

. . not applicable

Table 2.2.3 FINAL NUMBER OF PERSONS IN SIH SAMPLE(a)

	CAPITAL CITY	BALANCE OF STATE	TOTAL
	no.	no.	no.

NSW	3 131	2 117	5 248
Vic.	3 474	1 338	4 812
Qld	1 607	2 236	3 843
SA	1 713	701	2 414
WA	1 909	929	2 838
Tas.	811	739	1 550
NT	666	161	827
ACT	783	. .	783
Aust.	14 094	8 221	22 315

. . not applicable
(a) Number of persons aged 15 years and above