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20.0.4 The information requirements of ABS household surveys are determined on the basis of submissions from users on their needs for and uses of household survey data. They also reflect ABS deliberations on what is required of a national statistics program in the various subject fields, based on user contact and consultation.
20.0.5 In the field of labour statistics, supplementary surveys provide detailed information on a range of labour topics and interest groups such as:
20.0.6 Many labour topics are covered on a regular basis, while others are only covered once or at irregular intervals to meet a specific need for information. Topics are usually run nationally. However, one month is set aside each year for State government proposed topics, specific to one or more States. The program also includes other social and economic topics not relating to labour statistics, such as the environment, crime and safety, and child care.
20.0.7 Estimates from each supplementary survey are released in separate publications. More detailed estimates are available on request. Confidentialised Unit Record Files are sometimes also produced.
20.0.8 In addition to those already excluded from the Labour Force Survey, the following persons are excluded from most supplementary surveys (see paragraphs 17.2 to 17.4 of Chapter 17 for further information):
20.0.9 Depending on the topic or population of interest for which information is being collected, there may be further exclusions from scope. For example, some supplementary surveys exclude all persons living in special dwellings; others collect information only from a certain population or interest group (e.g. information on retirement is collected from persons aged 45 years or over).
20.0.10 The collection methodology for the supplementary surveys is generally the same as for the Labour Force Survey. Interviews are conducted at the same time as interviews for the Labour Force Survey. Most interviews (about 70%) are conducted by telephone, with the remainder conducted face-to-face.
20.0.11 Information about each household member in scope of the supplementary survey is generally collected from one adult using the ARA methodology.
20.0.12 Response rates for the supplementary surveys are slightly lower than for the Labour Force Survey, and average around 93%.
20.0.13 The supplementary surveys use the same sample design as the Labour Force Survey, and the sample used in the supplementary surveys is a subset of the Labour Force Survey sample. Persons in the outgoing rotation group in the Labour Force Survey are excluded from all supplementary surveys.
20.0.14 The sample size for the supplementary surveys varies. In addition to the scope exclusions listed above, there may be further restrictions to the supplementary survey sample for particular topics.
20.0.15 Post-stratification estimation techniques are generally used, with adjustment to account for persons enumerated outside their State of usual residence.
20.0.16 Supplementary survey weights use labour force estimates, referred to in this context as pseudo-benchmarks, to supplement independent demographic benchmarks (see Chapter 17 for further information on population benchmarks used in household surveys). Supplementary surveys may also incorporate other auxiliary information on target populations - for instance benchmarks for the Indigenous population, or the private dwelling population - into estimates.
20.0.17 The post-stratification variables generally used are:
TIME SERIES ESTIMATES
20.0.18 Seasonally adjusted and trend estimates are not produced for supplementary surveys.
RELIABILITY OF THE ESTIMATES
20.0.19 Estimates from supplementary surveys are subject to both sampling and non-sampling error (see Chapter 16 for more detail). The relative standard errors of survey estimates are published in each supplementary survey publication.
20.0.20 A 'split-halves' variance estimator, with a Taylor series adjustment for the post-stratified estimate, is used to calculate estimates of variance (see Chapter 16 for more detail).
DATA COMPARABILITY OVER TIME
20.0.21 Estimates from successive supplementary surveys on a given topic may not be strictly comparable over time due to changes in survey scope and concepts measured. In addition, changes affecting the Labour Force Survey sample and estimation processes will affect supplementary survey estimates. For further discussion of changes to a particular labour topic see Sections 1 to 16 of this chapter.
20.0.22 For further details contact the Assistant Director, Monthly and Multi-purpose Population Surveys Section, on Canberra (02) 6252 6660.