Appendix: Summary of SIH 2019-20 sample differences according to linkage status and imputation outcomes
The table below provides a summary of selected characteristics of people aged 15 years and over who participated in SIH, according to their linkage status. This has two distinct values:
- Unlinked - people are missing admin income information either due to unsuccessful linkage to a PLIDA spine ID, or because the people are associated with multiple spine IDs exist in at least one PLIDA source used.
- Linked – people with linkage to a PLIDA spine ID, and this spine ID is not replicated in any PLIDA source used.
Additionally, the total for all people is presented alongside linkage status for comparison.
All statistics are weighted using SIH 2019-20 survey weights.
| Characteristic | Unlinked | Linked | Total |
|---|---|---|---|
| Husband, wife or partner in household | 56% | 61% | 61% |
| Resident of a non-family household | 22% | 16% | 16% |
| Lives in a major urban area | 75% | 74% | 74% |
| Employed | 63% | 62% | 62% |
| Mean age | 42.1 years | 46.1 years | 45.7 years |
| Median age | 39 years | 45 years | 44 years |
| SIH survey weight (median) | 1,161 | 1,068 | 1,080 |
| Main source of personal income | |||
| Employee income | 56% | 55% | 55% |
| Own unincorporated business | 3% | 3% | 3% |
| Government pensions and allowances | 19% | 21% | 20% |
| Investment | 8% | 8% | 8% |
| Superannuation pensions and annuities | 2% | 5% | 5% |
| Other regular transfers | 5% | 2% | 2% |
Total incomes, as reported in SIH, for the Unlinked and Linked groups are displayed in the graph below in $100 ranges.
Comparison of reported and imputed incomes for unlinked and linked people
Mean SIH-reported incomes, of total income and for each income type, for unlinked and linked groups, and for the total population (linkage status ignored), are presented in the first table below. This is followed by a comparable table for income derived from admin sources.
Compared to linked persons, unlinked people report lower average incomes across most income types. The exception is for other regular transfers, where the unlinked mean income is double the corresponding linked value.
| Unlinked | Linked | Total population | ||
|---|---|---|---|---|
| SIH reported current income ($ per week) | Total income | 1,031 | 1,133 | 1,121 |
| Employee income | 777 | 842 | 834 | |
| Own unincorporated business income | 34 | 42 | 41 | |
| Government pensions and allowances | 93 | 103 | 102 | |
| Investment income | 61 | 73 | 71 | |
| Superannuation pensions and annuities | 28 | 53 | 50 | |
| Other regular transfers | 36 | 18 | 20 |
(a) Estimates include Commonwealth Rent Assistance, which contribute less than $2 to mean total income
In a similar manner to Table 17, the admin income results in Table 18 show that, for both annual and current income estimates, the mean total income imputed for unlinked people is lower than that for linked people. However, compared to Table 17, Table 18 shows some notable differences. One is that the unlinked group has a higher mean employee income than the linked group. Another is that, for both current and annual income estimates, the mean of other regular transfers income is similar across linked and unlinked groups. This indicates that donor information is more likely to reflect employee income rather than other regular transfers, likely due to limitations in how the latter is captured in admin data sources.
| Unlinked | Linked | Total population | ||
|---|---|---|---|---|
| Admin current income ($ per week) | Total income | 1,090 | 1,129 | 1124 |
| Employee income | 867 | 849 | 851 | |
| Own unincorporated business income | 36 | 61 | 58 | |
| Government pensions and allowances | 84 | 99 | 97 | |
| Investment income | 67 | 78 | 77 | |
| Superannuation pensions and annuities | 33 | 40 | 39 | |
| Other regular transfers | 3 | 3 | 3 | |
| Admin annual income ($ per week) | Total income | 1,073 | 1,110 | 1,106 |
| Employee income | 846 | 827 | 829 | |
| Own unincorporated business income | 36 | 61 | 58 | |
| Government pensions and allowances | 91 | 103 | 101 | |
| Investment income | 67 | 79 | 78 | |
| Superannuation pensions and annuities | 30 | 38 | 37 | |
| Other regular transfers | 3 | 3 | 3 |