6527.0 - Household Expenditure Survey, Australia: User Guide, 1998-99

ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 15/11/2001

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Contents >> Chapter 3. Survey methodology

Scope
Coverage
Data collection
Interviewing procedures
Data processing
Coding and input editing of household and individual schedules
Diary coding
Editing

SCOPE

Residents of private dwellings in all areas of Australia except remote and sparsely settled areas were in scope. Also excluded were households containing foreign defence force staff, foreign diplomats or diplomatic staff.

Private dwellings were houses, flats, home units, caravans, garages, tents and other structures that were used as places of residence at the time of interview. These were distinct from special dwellings which included hotels, boarding houses and institutions. Residents of special dwellings were excluded because of differences in their lifestyle and accommodation.
Remote and sparsely settled areas were areas in which there were less than 0.06 dwellings per square kilometre.

For most states and territories the exclusion of people in sparsely settled areas has only a minor impact on any aggregate estimates that are produced because they only constitute a small proportion of the population. However, this is not the case for the Northern Territory where such persons account for over 20% of the population.

COVERAGE

Information was collected only from usual residents. Usual residents were residents who regarded the dwelling as their own or main home. Others present were considered to be visitors and were not asked to participate in the survey.

DATA COLLECTION

Information for each household was collected using:

a computer-assisted household interview questionnaire which collected information on household characteristics, expenditure common to all household members (e.g. health service payments), and irregular or infrequent expenditure (e.g. household appliances and holidays overseas);
a computer-assisted individual interview questionnaire which collected information on income and other personal characteristics; and
a personal diary in which people recorded their expenditure over two weeks.

Sample copies of the above documents are available for purchase - see chapter 6 for details.

INTERVIEWING PROCEDURES

Experienced ABS interviewers were employed to collect HES data. They were given comprehensive training and were provided with detailed written instructions to complement the survey documents.

Interviewers maintained contact with households over a series of visits. The visits and their sequence were as follows:

initial contact interview
- The interviewer 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 talk with all the usual residents of the dwelling as a group. If that was not possible, then additional interviews were arranged to ensure that all usual residents were covered by the survey.
the placement interview. Ideally all usual residents of the dwelling were present for this interview and the interviewer:

completed one household questionnaire for each household usually resident in the dwelling;
completed an individual questionnaire for each usual resident aged 15 years and over; and
provided each usual resident aged 15 years and over with a diary in which they were asked to record details of each purchase they made over the following two weeks, starting the day after the interview.

If a usual resident could not be present for the interview, or for reasons of confidentiality requested to have a private interview, the interviewer returned at an agreed time and added the person’s information to his or her household’s household questionnaire and completed the person’s individual questionnaire.

diary visits

Three diary visits were performed. The first was between two and four days after the placement interview to ensure that survey participants were not having difficulties. The second was to pick up the first week’s diary and to drop off the second. The third was at the end of the diary keeping period, and was to pick up the second diary and thank participants for their help in providing HES information.

DATA PROCESSING

Computer based systems were used to process the data from the 1998-99 HES with a program known as BLAISE. It was necessary to employ a variety of methods to process and edit the data which reflected the different questionnaires used to collect data from the household, individual and diary components of the surveys. These processes are outlined below.

Coding and input editing of household and individual schedules

Internal system edits were applied in the computer-assisted interview (CAI) questionnaire to ensure the completeness and consistency of the questionnaire. 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 in each State or Territory. There, 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 editing was performed on responses to questions on country of birth, occupation and industry of employment to ensure completeness, and family relationships, to assign individuals’ relationships within household, family and income units.

Diary coding

HES diaries were collected from respondents some two weeks after the initial household interview. They were then dispatched along with the electronic transfer of household and individual schedule information. All reported expenditures in the diaries were entered using the BLAISE Diary Processing System. The BLAISE system helped operators to code diary items into HEC codes. A trigram coder enabled operators to select the appropriate good or service from an alphabetically ordered pick list of options. The system also deleted expenditure recorded in the diaries on items covered by the household questionnaire. For example, the household questionnaire collected information on mains gas payments so any payments coded to HEC code 02010102 (Mains Gas - selected dwelling) were automatically deleted.

The complete list of items classified to each expenditure code is called the HEC coding list and is available for purchase by researchers who need a detailed knowledge of the content of each expenditure code. For example, a researcher may need to know the contents of HEC code 03090301 Potato crisps and other savoury confectionery which the HEC coding list shows to contain bahl chipletts, Burger rings, Cheezels, chips (crisps), chips (not hot), corn chips, Le snack, pretzels, Snack attack and many others. During coding of data, there was a level of manual involvement in adding codes to the coding list for goods not already listed and for variant spelling and punctuation of reported expenditures.

Editing

A range of processes was applied to the diary information to check that expenditure items as well as values had been recorded; that specific values were correctly coded if they were unusually high or low; that errors had not occurred in coding; and that relationships between household and diary information were consistent. A Query Resolution System ensured that:

an accurate record of decisions was made in resolving the queries;
coding of products was consistent;
the HEC coding list was updated for unusual or unknown products;
coders could continue to process diaries if they could not resolve an issue within a short time.

A range of edits was also applied to the household, individual and diary 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.

After unusually high expenditure and income values (termed statistical outliers) were investigated to determine whether there had been errors in entering the data, such values were also examined for their effect on total income and expenditure estimates for Australia. As a result, a small number of outliers were winsorised, that is, the values were reduced to the next highest recorded value. Winsorisation aims to improve the reliability of estimates and was considered where analysis showed that the unaltered values significantly affected the distribution of the Australia level total household expenditure and income estimates.