EXPLANATORY NOTES
INTRODUCTION
1 This publication contains results from the Western Australia (WA) Housing Motivations and Intentions (HMI) Survey, which was conducted throughout WA in October 2012 as a supplement to the Australian Bureau of Statistics (ABS) monthly Labour Force Survey (LFS). The HMI Survey collected data on current and previous dwelling characteristics, the factors that influence individual's housing decisions, and their future housing intentions. The previous HMI Survey was conducted in October 2005.
2 The publication Labour Force, Australia (cat. no. 6202.0) contains information about the LFS survey design, scope, coverage and population benchmarks. This information also applies to the supplementary surveys. The LFS publication also contains definitions of demographic characteristics and information about computer assisted and telephone interviewing which are relevant to both the monthly LFS and supplementary surveys.
SCOPE
3 The WA HMI Survey includes dwellings in urban, rural, remote and very remote areas. The scope was restricted to persons aged 18 years and over who were usual residents of private dwellings and excluded the following:
- members of the Australian permanent defence forces
- certain diplomatic personnel of overseas governments, customarily excluded from censuses and surveys
- overseas residents in Australia
- members of non-Australian defence forces (and their dependents) stationed in Australia
- people living in discrete Indigenous communities (for operational reasons).
COVERAGE
4 In the LFS, coverage rules are applied which aim to ensure that each person is associated with only one dwelling, and hence has only one chance of selection in the survey. See
Labour Force, Australia (cat. no. 6202.0) for more detail.
DATA COLLECTION
5 Information was collected either through face-to-face or telephone interviews conducted over a two week period during October 2012. Information was collected from
any responsible adult (ARA) in the household on behalf of one person who was randomly selected from the household. The ARA answered questions regarding their current dwelling's structure, tenure type, number of bedrooms, dwelling status at time of purchase and total household income.
6 The sample for the HMI Survey was approximately 3,600. After taking into account sample loss, the response rate for the survey was 90%. In total, information was collected from 2,796 fully responding households.
ESTIMATION METHOD
Weighting
7 Weighting is the process of adjusting results from a sample survey to infer results for the total 'in scope' population. To do this, a 'weight' is allocated to each enumerated person or household. The weight is a value which indicates how many people or households in the population are represented by the sample person or household.
8 The first step in calculating weights for each unit is to assign an initial weight, which is the inverse of the probability of being selected in the survey. For example, if the probability of a person or household being selected in the survey was 1 in 600, then the person or household would have an initial weight of 600 (that is, they represent 600 people or households).
Benchmarks
9 The initial weights are then calibrated to align with independent estimates of the population, referred to as benchmarks. The population included in the benchmarks is the survey scope. This calibration process ensures that the weighted data
conform to the independently estimated distribution of the population described by the benchmarks rather than to the distribution within the sample itself. Calibration to population benchmarks helps to compensate for over or under-enumeration of particular categories of people or households which may occur due to either the random nature of sampling or non-response.
10 The survey uses estimated resident population (ERP) based person benchmarks for WA, as at 31 October 2012.
Estimation
11 Survey estimates of counts of people or households are obtained by summing the weights of people or households with the characteristic of interest.
RELIABILITY OF ESTIMATES
12 Estimates in this publication are subject to sampling and non-sampling errors:
- Sampling error is the difference between the published estimate derived from a sample of dwellings and the value that would have been produced if all dwellings in scope of the survey had been included. For further information, refer to the Technical Note.
- Non-sampling error may occur in any collection whether it is based on a sample or a full count of the population such as a census. Sources of non-sampling error include non-response, errors in reporting by respondents or recording answers by interviewers, and errors in coding and processing data. Every effort is made to reduce the non-sampling error by careful design and testing of the questionnaire, training of interviewers, extensive editing and quality control procedures at all stages of data processing and follow-up of respondents.
DATA QUALITY
13 Information recorded in this survey is essentially 'as reported' by respondents and hence may differ from that which might be obtained from other sources or via other methodologies. This factor should be considered when interpreting the estimates in this publication.
14 Information was collected on respondents' housing intentions. Intentions are influenced by a number of factors and can change quickly. Care should therefore be taken when analysing or interpreting the data.
INTERPRETATION OF RESULTS
15 How to read Tables 9 and 17 of the Data Cube:
Tables 9 and 17 of the Data Cube present location data at two points in time in a matrix e.g. current location by previous location. Aside from the totals, each of the other categories presented in the tables are mutually exclusive. The matrix format can be complicated to interpret, therefore an explanation of how to read these tables is included below:
Examples:
Table 9 cross classifies recent movers' current dwelling location by their previous dwelling location based on the Australian Statistical Geography Standard (ASGS).
In the example table below:
- Cell 'a' is the estimate of the number of people who currently live in Greater Perth whose previous dwelling was within the same suburb/town/locality e.g. John Smith who lives in Mandurah moved a few streets down within the same suburb.
- Cell 'b' is the estimate of the number of people who currently live in Greater Perth whose previous dwelling was within Greater Perth, but in a different suburb e.g. John Smith who lived in Fremantle moved to Mandurah.
- Cell 'c' is the estimate of the number of people who currently live in Greater Perth whose previous dwelling was in Rest of WA e.g. John Smith who lived in Karratha moved to Mandurah.
- Cell 'd' is the sum of 'a', 'b' and 'c' (i.e. the estimate of the number of people who currently live in Greater Perth whose previous dwelling was in WA).
- Cell 'e' is the estimate of the total number of recent movers whose previous dwelling was located in WA.
To calculate the proportion of recent movers in Western Australia who moved either
within or
to Greater Perth, you would divide cell '
d' by cell '
e' and multiply by 100.
The same method applies to Table 17 which cross classifies future movers' current dwelling location by their preferred future dwelling location based on the ASGS.
For further information on the geographic classification, see the
Glossary.
Income
16 Equivalised income is often used as an indicator of economic wellbeing, however, there are some circumstances where income may be misleading. ABS household surveys have shown that households in the lowest income quintile have large differences in household net worth (see paragraphs 17 and 18). A significant number of low income households have levels of net worth that places them in the highest net worth quintiles. These households would not be considered as having low economic wellbeing as their levels of net worth would allow them to fund additional consumption. As a significant number of Australian households are both low income and high worth, inappropriate conclusions may be drawn if household income is solely used to assess economic wellbeing.
17 Net worth, often referred to as wealth, is the value of a household's assets less the value of its liabilities. Assets can take many forms including:
- produced tangible fixed assets that are used repeatedly and for more than one year, such as dwellings and their contents, vehicles, and machinery and equipment used in businesses owned by households
- intangible fixed assets such as computer software and artistic originals
- business inventories of goods
- non-produced assets such as land
- financial assets such as bank deposits, shares, superannuation account balances, and the outstanding value of loans made to other households or businesses.
18 Liabilities are primarily the value of loans outstanding including:
- mortgages
- investment loans
- credit card debt
- borrowings from other households
- debt on other loans such as personal loans to purchase vehicles and study loans.
19 The WA HMI Survey did not collect information on net worth. For further information on households with low economic resources (income and wealth) see the feature article in
Household Wealth and Wealth Distribution, Australia, 2009-10 (cat. no. 6554.0) and
Household Income and Income Distribution, Australia, 2009-10 (cat. no. 6523.0).
DATA COMPARABILITY
20 Housing Motivations and Intentions was also the State Supplementary Survey topic in 2005. Factors that affect the comparability of 2012 estimates with those of 2005 are described below.
The following data items presented in Table 1 of the Data Cube are directly comparable:
- Current dwelling type
- Length of time in current dwelling
- Senior household
- Total recent movers
- Total future movers.
The following data items are not comparable due to major changes to the collection methodology:
- 'Area of usual residence': In 2005, 'Area of Usual Residence' was classified according to the Australian Standard Geographical Classification (ASGC), whereas in 2012, 'Area of Usual Residence' is classified according to the Australian Statistical Geography Standard (ASGS). The ASGC has been replaced by the ASGS as the Australian Bureau of Statistics' geographical framework. The ASGS has been designed to better meet the statistical needs of users and to address some of the shortcomings of the ASGC. In particular, the ASGS is a more stable structure (i.e. the ASGS will remain stable for the five years between Censuses, whereas the ASGC was reviewed annually), and the regions are more consistent in population size, optimised for the statistical data to be released, and represent functional areas. For further information, see the Geography section of the ABS website.
- 'Dwelling tenure' (current and previous): In 2005, one question was used to determine dwelling tenure, whereas in 2012, four questions were used. This change was made in order to more precisely classify tenure types such as rent buy schemes, shared equity schemes, life tenure schemes, rent-free and other tenure types, which have become more common in the last few years.
- 'Landlord type' (current and previous): In 2012, the question was worded differently and the output categories are more detailed. In addition, in 2012, the 'Don't know' category was removed for current landlord type. Responses to the tenure type questions also determine which households were asked about their landlord type. In 2005, only renters were asked about their landlord type, whereas in 2012, renters and people participating in rent/buy or shared equity schemes were asked this question.
- 'Reasons for choice of dwelling location' (current and future): Some response categories have been removed from this question, while the response categories 'Cheaper rent or rent free', 'Suitable price range' and 'To reduce mortgage' which were separate questions in 2005, have been added in 2012. In addition, in 2012, these three categories were made available as response options to the question depending on the respondent's tenure type and as noted above, the tenure type variable has also changed. In 2012, a 'Don't know' category was also added, as the related question is answered by the ARA who may not know the reasons.
- 'Reasons for choice of dwelling' (current and future): Some categories have been removed from this question, while the response categories 'Larger residence', 'Smaller residence', 'Larger block' and 'Smaller block' which were asked as separate questions in 2005, have been added in 2012. In addition, in 2005, the respondents were asked these questions based on their choice of dwelling type and their reasons for choosing the dwelling type, whereas in 2012, all respondents were able to choose these response options. In 2012, a 'Don't know' category was also added, as the related question is answered by the ARA who may not know the reasons.
- 'Change in selected personal or family circumstances that resulted in move': In 2005, respondents were asked whether a change in personal or family circumstances had prompted a move, and if so, they were then asked to choose reasons from a pick-list of responses. In 2012, respondents were asked directly to indicate if selected personal or family circumstances had prompted a move, with fewer response options available. The response category "Moving out of your parents' or guardians' home" was added in 2012 and was available to respondents aged 35 years or less.
- 'Future housing for persons aged 55 years and over': In 2005, respondents were asked this question if any usual resident in the household was aged 55 years and over, whereas in 2012, the respondent was only asked this question if the randomly selected person was aged 55 years and over.
- 'Preferred number of bedrooms in future dwelling': In 2012 a 'Don't know' category was added, as the related question is answered by the ARA who may not know the preferred number of bedrooms.
- 'Family composition of household': In 2005, the 'Household composition' classification was used to describe type of household, whereas in 2012, the 'Family composition of household' classification was used to describe type of household. The 'Family composition of household' classification utilises the 'Family type' and 'Household type' classifications.
- Income: In 2005, two questions were asked to determine which of three ranges annual household income was within, whereas in 2012, a series of more detailed questions, including prompts for sources of income, were used to determine household income more accurately. In addition, in 2012, income data is output in the publication as equivalised weekly household quintiles (see Glossary for definition) rather than as annual household income ranges.
Caution should be used when comparing the following data items due to changes in the populations that were asked the questions relating to:
- dwelling status at time of purchase
- previous dwelling type
- number of bedrooms in previous dwelling
- preferred future dwelling type
- whether home ownership is the main reason for moving.
The 'Modifications made to current dwelling' data item is not available for the 2012 survey.
21 Caution should be used when comparing statistics from the WA HMI survey with data from the Census of Population and Housing, and other related publications, as different methodologies or classifications may have been used.
CLASSIFICATIONS
22 Area of usual residence is classified according to the
Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2011 (1270.0.55.001).
PRODUCTS AND SERVICES
Data Cube
23 All tables in this product release are available in a Data Cube from the Downloads tab of this publication. For a list of tables in the Data Cube, please refer to the contents page of the spreadsheet. Footnotes are included in the spreadsheet as cell comments. Footnoted cells can be identified by a red indicator in the corner of the cell. The comment appears when the mouse pointer hovers over the cell.
CUSTOMISED DATA REQUESTS
24 Findings from the WA HMI 2012 State Supplementary Survey are available free of charge in web and Excel format from the ABS website. Additional data may be available on request. Note that detailed data can be subject to high relative standard errors, and in some cases, may result in data being confidentialised. All inquiries should be made to the
National Information and Referral Service on 1300 135 070.
ACKNOWLEDGMENT
25 ABS publications draw extensively on information provided freely by individuals, businesses, governments and other organisations. Their continued cooperation is very much appreciated. Without it, the wide range of statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the
Census and Statistics Act, 1905.
NEXT SURVEY
26 It is unknown at this stage whether the survey will be run again.
RELATED INFORMATION
27 Related information on this topic can be found through the following websites:
28 Links to other data releases relating to Western Australia can be found on the ABS website, via the Regional portal, under
Topics @ a Glance.
29 For further information about these or related statistics, contact the
National Information and Referral Service on 1300 135 070.
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