4.7 SUMMARY OF CHANGES IN EARLIER SURVEYS
INTRODUCTION
This section outlines the main changes in comparability of expenditure collections since 1984 and the income collections since 1994-95. Changes introduced in 2003-04 are not included as they are discussed in sections 4.1 to 4.6. Changes prior to 2003-04 have been much less significant than the recent changes. Some of the differences which should be taken into account when performing comparisons of survey results over time are presented in this section.
The final sample size of HES cycles from 1984 and SIH cycles from 1994-95 is shown in table 4.7.1. The sample size can give an indication of the reliability of the estimates produced from the surveys.
Table 4.7.1 Previous HES and SIH sample sizes |
|  |
| | Capital city | Balance of state | Total | |
| |
| HES | | | | |
| 1984 | 6 896 | 2 675 | 9 571 | |
| 1988-89 | 5 263 | 2 142 | 7 405 | |
| 1993-94 | 6 107 | 2 282 | 8 389 | |
| 1998-99 | 4 795 | 2 098 | 6 893 | |
| 2003-04 | 4 907 | 2 050 | 6 957 | |
| SIH | | | | |
| 1994-95 | 4 438 | 2 381 | 6 819 | |
| 1995-96 | 4 588 | 2 375 | 6 963 | |
| 1996-97 | 4 715 | 2 530 | 7 245 | |
| 1997-98 | 4 649 | 2 376 | 7 025 | |
| 1999-2000 | 4 327 | 2 310 | 6 637 | |
| 2000-01 | 4 397 | 2 389 | 6 786 | |
| 2002-03 | 6 657 | 3 554 | 10 211 | |
| 2003-04 | 7 077 | 4 284 | 11 361 | |
| |
SIH CHANGES
The SIH cycles from 1994-95 to 2002-03 are very comparable. These files were reprocessed in 2003 to apply consistent demographic benchmarks to all years, and to incorporate the latest demographic estimates in the benchmarks. Changes over this period are generally minor and are summarised below:
- an extra benchmark was used in the weighting process in 1999-2000 and 2000-01 to compensate for an apparent fall in the coverage of government benefit payments in those years
- any changes to government pensions and allowances have been incorporated
- the 2nd edition of the Australian Standard Classification of Occupations (cat. no. 1220.0) was introduced from 1996-97 for coding of occupation.
In addition, the item nature of occupancy was replaced by tenure type from 1995-96. Prior to 1995-96 owner occupiers were classified as either owners or purchasers. A purchaser had a mortgage or loan secured against the dwelling, and the loan was used to purchase or build the dwelling. An owner had no loan secured against the dwelling for the purpose of building or purchasing. From 1995-96, owner occupiers are classified as owners without a mortgage and owners with a mortgage. This change to the classification was made to reflect the increasing diversity in financial instruments, in particular the increasing use of loans secured against dwellings being used for non-housing purposes. Such secured loans have implications for the security of tenure and a household with such a loan is classified as an owner with a mortgage in the new classification.
HES CHANGES
Comparability in the concepts, classifications and methodology employed in the HES was maintained where possible between 1984 and 1998-99. However some changes were made to incorporate new standards and to improve data quality. In particular the Household Expenditure Classification (HEC) was introduced in 1998-99 - it replaced the Household Expenditure Commodity Code List (HESCCL) which had been in use since 1984. The changes involved updating the classification to include new items of expenditure, and restructuring the classification. At the most detailed level, the HESCCL used in 1993-94 had 463 categories while the HEC used in 1998-99 had 609 categories. Despite the changes, 78% of categories at the published level were unchanged between 1993-94 and 1998-99, and there were only minor changes at the major group level of the classification.
Other significant differences over this period are as follows:
- independent estimates of the number of households in Australia were incorporated into the weighting system from 1993-94; prior to this, the number of households estimated from the HES differed from actual household counts - for example, in 1988-89 the HES estimate of the number of households was 5.4 million, while the actual number of households in Australia at that time was estimated to be 5.9 million
- more extensive use was made of imputation from 1993-94
- any changes to government pensions and allowances have been incorporated
- the item nature of occupancy was replaced by tenure type from 1998-99 (see details of this change above)
- the 2nd edition of the Australian Standard Classification of Occupations (cat. no. 1220.0) was introduced in 1998-99 for coding of occupation
- in 1993-94 and previous surveys, the definition of dependent children aged 15 and over included full-time students aged 15 to 20 who had a parent or other relative in the household (but no partner or child of their own); in 1998-99 this was changed to include full-time students aged 15-24 who have a parent in the household (but no partner or child of their own)
- industry of employment was first collected in 1998-99
- in the 1984 HES negative incomes were set to zero whereas in all subsequent HES cycles they have been left as negative
- income tax in both the 1984 and 1988-89 HES was based on reported data with non-response imputed whereas in more recent HES cycles (and all SIH cycles) income tax has been entirely imputed using the relevant taxation criteria and the income and other characteristics of household members as reported in the survey.
More information on the comparability between the 1998-99 HES and previous HES cycles can be found in the 1998-99 issue of Household Expenditure Survey: User Guide (cat. no. 6527.0).
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