4326.0.30.002 - Technical Manual: National Survey of Mental Health and Wellbeing, Confidentialised Unit Record Files, 2007 Quality Declaration
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 15/04/2009
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The household level records contain information derived from the income of all persons in the household, aged 15 years and over:
When analysing income at the person and household level, it is necessary to exclude the special codes (eg 'not stated'). The data item list provides the relevant values.
Income not reported
If more than one contributing income item at the person level has a value of 'Not known', then totals derived from these items, such as 'Gross weekly personal income' are also set to 'Not known', as it was not possible to derive an accurate total. Similarly, if one or more of the contributing person records in a household has a value of 'Not known', then household income and derived income deciles are set to 'Not known/no income reported'. Care should be taken to exclude these codes when categorising higher income values, and when calculating means, medians and other summary statistics.
Calculating income deciles
Deciles are groupings that result from ranking either all households or all persons in the population in ascending order according to some characteristic, such as income, and then dividing the population into 10 equal groups, each comprising 10% of the estimated population. The first decile contains the bottom 10%, the second decile contains the next 10% and so on.
To assist in the use and interpretation of income deciles at the person or household level, it is necessary to exclude the reserved values of:
Refer to 'Income not reported' for more information on the treatment of 'Not known or not stated' values.
The following table provides the decile ranges for gross weekly cash income of persons (INCDECPN) and of households (INCWKHHD):
Gross weekly equivalised income of households
Equivalised household income provides an indication of the economic resources available to each member of a household. It can be used for comparing the situation of individuals, as well as comparing the situation of households. Equivalence scales are used to make adjustments to the actual incomes of households so that households of differing sizes and compositions are able to be compared. The gross weekly equivalised income of households is expressed in:
Equivalised income is calculated by deriving an equivalence factor according to the chosen equivalence scale, and then dividing income by the factor. The equivalence factor, derived using the 'modified OECD' equivalence scale, is determined by allocating the following points to each person in a household:
Equivalised household income is derived by dividing the total household income by a factor equal to the sum of the equivalence points allocated to the household members. The equivalised income of a lone person household is the same as its unequivalised income. The equivalised income of a household comprising more than one person lies between the total value and the per capita value of its unequivalised income.
When unequivalised household income is negative, such as when a loss is reported for an individual's unincorporated business or other investment income, and this loss is greater than any positive income from any other source, then equivalised household income is set to zero.
When analysing the gross weekly equivalised income of households, it is necessary to exclude the special codes (eg 'not stated'). The data item list provides the relevant values.
The following table provides the decile ranges for gross weekly equivalised income of households (INCDECEH):