DATA COLLECTION AND PROCESSING

DATA COLLECTION

Interview procedures

Trained ABS interviewers were used to collect Survey of Income and Housing (SIH). They were given comprehensive training and were provided with detailed written instructions to complement the survey documents.

Information for each household was collected using:

• a household level computer assisted personal interview questionnaire which collected information on household characteristics, housing costs, expenditure common to all household members (e.g. utility bills), and irregular or infrequent expenditure (e.g. household appliances and holidays overseas) and certain assets and liabilities for all households.
• an individual level computer assisted personal interview questionnaire which collected information on income, certain assets and liabilities, and personal characteristics from each usual resident aged 15 years and over in all households.

For SIH interviews, the interviewer:

• made an initial contact visit, in which they obtained information on the numbers and characteristics of people usually resident in the dwelling. If a responsible adult was not available, the interviewer called back at another time. The interviewer also arranged a convenient time to call back to conduct the interviews.
• completed one household questionnaire for each household (information was provided by a household spokesperson who was nominated as the best person to provide information on the financial situation of the household).
• completed an individual questionnaire for each usual resident aged 15 years and over.
• completed a proxy interview when the parent/guardian of children in the household aged 15–17 years, if they did not give permission for them to be personally interviewed, or when a person was incapable of answering on their own behalf.

Data collection instruments

A representation of the computer-assisted interview (CAI) questionnaires used in the SIH can be downloaded as separate PDF files available from the 'downloads' tab of this publication.


DATA ITEMS

For details of the data items available from the 2017–18 SIH see the Excel spreadsheet available as a data cube from the 'downloads' tab of this publication.


DATA PROCESSING AND DERIVATIONS

Data processing methods

Computer based systems were used to collect and process the data from the 2017–18 SIH with a software program known as BLAISE. A variety of methods were employed to process and edit the data, reflecting the different questionnaires used to collect data from the household and individual components of the surveys. These processes are outlined below.

Coding and input editing of household and individual questionnaires

Internal system edits were applied in the CAI questionnaires to ensure the completeness and consistency of the responses being provided. The interviewer could not proceed from one section of the interview to the next until responses had been appropriately completed.

A number of range and consistency edits were programmed into the CAI questionnaire. Edit messages automatically appeared on the screen if the information entered was either outside the permitted range for a particular question, or contradicted information already recorded. These edit queries were resolved on the spot with respondents.

Data from the CAI questionnaires were electronically loaded to the processing database on receipt in the ABS office. Office checks were made to ensure data for all relevant questions were fully accounted for and that returns for each household and respondent were obtained. Problems identified by interviewers were resolved by office staff, where possible, based on other information contained in the schedule, or on the comments provided by interviewers.

Computer-assisted coding was performed on responses to questions on country of birth, occupation and industry of employment and educational qualification to ensure completeness. Data on relationships between household members were used to delineate families and income units within the household, and to classify households and income units by type.

Additional editing

A range of edits was also applied to the household and individual information to double check that logical sequences had been followed in the questionnaires; that specific values lay within expected ranges; and that relationships between items were consistent. Unusually high values (termed statistical outliers) were investigated to determine whether there had been errors in entering the data and corrections were made where necessary.

Imputation for missing records and values

Some households did not supply all the required information but supplied sufficient principal information to be retained in the sample. Such partial responses occur when:

• income or other data in a questionnaire are missing from one or more non-significant person's records because they are unable or unwilling to provide the data,
• all key questions are answered by the significant person(s) but other questions are not answered. Significant person(s) are the main income earners for the household (e.g. both parents in a couple family with children household, half of all persons in a group household, see glossary for further information)

In the two cases of partial response above, the data provided are retained and the missing data are imputed by replacing each missing value with a value reported by another person with similar characteristics, referred to as the 'donor'.

Donor records are randomly selected by finding fully responding persons with matching information on multiple characteristics, such as state, sex, age, labour force status and income, as the person with missing information. As far as possible, the imputed information is an appropriate proxy for the information that is missing. Depending on which values are to be imputed, donors are randomly chosen from the pool of individual records with complete information for the block of questions where the missing information occurs.

The final SIH sample includes 3,745 households (27% of households) and 9,946 person records (30% of persons aged 15 years or over) which had at least one imputed value.


MODELLED ITEMS

Modelled data items

Some data items of interest cannot reliably be collected from respondents, and some cannot be collected at all. However, it is sometimes possible to utilise other information provided by respondents as a basis for estimating the data items of interest. This process is referred to as modelling.

Child Care

Childcare subsidies assist families with dependent children with the costs of childcare. Two subsidies are collected and modelled in the 2017–18 SIH. These are the Child Care Benefit and Child Care Rebate.

Child Care Benefit (CCB) is a payment from the Australian Government that assists families with the costs of registered or approved child care. The scheme is means-tested and allocates an hourly amount that can either be provided to child care consumers after child care has been paid, or directly paid to child care providers, thereby reducing the upfront child care fees payable by the consumer.

Child Care Rebate (CCR) is also an Australian Government payment that, like CCB, assists families with the cost of child care. Each child care consumer is entitled to CCR, which is 50% of their net child care costs. That is, a child care consumer is entitled to 50% of their child care costs after CCB has been deducted from the cost if they receive it, or else 50% of the whole cost. CCR payments accrue up to a per child, per year limit ($7,613 per child per year in 2017–18). CCR, like CCB, may be paid either to the consumer in a lump sum or directly to child care providers, thereby further reducing the upfront cost of child care.

Estimates of CCB and CCR are collected from the child care questions, however there has been a substantial gap between the reported number of households receiving child care subsidies and the total value of that assistance, compared to administrative records. CCB and CCR have been modelled to improve the accuracy of estimates of these payments. The output data is made up of both reported and modelled data. Child care assistance is conceptually treated as social transfers in kind, including administrative overhead as part of the value of the transfer.

The modelled amounts of CCB and CCR are available at the household and income unit level.

Income tax and the Medicare levy and levy surcharge

Disposable income is calculated by deducting income tax, including the Medicare levy, from gross income.

The model is based on the liability rules described in the Tax Pack from the Australian Tax Office for the year concerned, the income reported by respondents, and other characteristics of household members reported in the survey.

Estimates of income tax are modelled, rather than collected from respondents, for a number of reasons including:

• An accruals approach is taken to estimating these items. The estimates relate to the tax liability being incurred with respect to the income being reported by the respondent in the survey. For estimates of current income, the current income tax liability is calculated as though the current income is the average income for the whole year. If actual income fluctuates during the year, respondents are unlikely to have an actual income tax assessment that is relevant to the required estimate.
• In addition to income changes during the course of the year, full year income tax assessments may be affected by changes in family or other circumstances of the respondent which are not described in the survey, and are best ignored when deriving an income tax estimate to use with the other survey data.
• Income tax assessments are only made after the end of the financial year, and therefore are not yet available at the time that current income is collected from respondents.
• The income tax assessment of respondents may be affected by certain expenditures which they make, such as donations to charities or other particular circumstances which are not captured in the survey. For many purposes it is desirable to exclude the impact on tax liabilities of specific influences which are not captured in the survey.
• The SIH provides sufficient relevant information to allow a relatively comprehensive tax model to be constructed.

The Medicare levy surcharge were also modelled and deducted from gross income in the calculation of disposable income.

For more information see the 'Income' section of this publication.

Balance of other Superannuation account

In SIH 2017–18, an issue with the survey instrument occurred where the value of regular income received for other superannuation, annuities or private pension accounts was not asked. As a result, data for this item was modelled with a regression method using previous year's data where values were collected.

The item impacted by this issue is:

• Balance of other superannuation pension accounts currently paying regular income (SUPBALOT)

This issue has been resolved in the survey instrument for the 2019–20 SIH collection.

Governments payment modelling

The eligibility-based modelling designed by the Department of Social Services (DSS) was introduced by the ABS in the 2015–16 SIH cycle. For the 2017–18 SIH, there were minor changes made to reflect policy and rate changes, and the types of payments available from DSS. Improvements to the accuracy of Family Tax Benefit were also included utilising the new (experimental) questions about children's living arrangement. Information about pension supplements was not asked of households, this information is entirely modelled.

Information about the model is available in Household Expenditure Survey and Survey of Income and Housing, User Guide, Australia - 2015-16.

Receipts of Family Tax Benefit are treated as income, regardless of whether they are received fortnightly or as a lump sum. The Newborn Supplement and Newborn Upfront Payment for those eligible receive it as part of their Family Tax Benefit Part A payments for a period of 13 weeks or with their lump sum. The Paid Parental Leave payment has also been included as income.

The Energy Supplement is included in income from government pensions or allowances. This tax-exempt, indexed payment is paid to pensioners, other income support recipients, families receiving Family Tax Benefit payments and Commonwealth Seniors Health Card holders, provided they meet eligibility requirements.