Mental health and experiences of homelessness methodology

1 This publication presents data on people who reported experiencing homelessness in the past, by whether or not they reported having a mental health condition, compiled from the 2014 General Social Survey (GSS). The survey collected information about personal and household characteristics for people aged 15 years and over resident in private dwellings across Australia (excluding very remote and people living in discrete Aboriginal and Torres Strait Islander communities), from March to June 2014.

2 The 2014 GSS collected data on a range of social dimensions from the same individual to enable analysis of the interrelationships in social circumstances and outcomes, including the exploration of multiple advantage and disadvantage experienced by that individual.

3 A full list of the data items from the 2014 GSS is available in the 4159.0 – General Social Survey: Summary Results, Australia, Data downloads section.

4 Only people who were usual residents of private dwellings in Australia were covered by the GSS. Private dwellings are houses, flats, home units and any other structures used as private places of residence at the time of the survey. People who usually reside in non-private dwellings such as hotels, motels, hostels, hospitals and short-stay caravan parks were not included in the survey. Usual residents are those who usually live in a particular dwelling and regard it as their own or main home. Visitors to private dwellings are not included in the interview for that dwelling. However, if they are a usual resident of another dwelling that is in the scope of the survey, they have a chance of being selected in the survey or, if not selected, they will be represented by similar persons who are selected in the survey.

5 The GSS was conducted in both urban and rural areas in all states and territories, except for very remote parts of Australia and discrete Indigenous communities. This exclusion is unlikely to impact on national estimates, and will only have a minor impact on any aggregate estimates that are produced for individual states and territories, except the Northern Territory where the excluded population accounts for over 20% of persons.

6 The Australian population at June 2014, after exclusion of people living in non-private dwellings, very remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities was 22,828,900, of which 18,463,700 were aged 15 years and over.

7 The following people were excluded from resident population estimates used to benchmark the survey results, and were not interviewed:

• diplomatic personnel of overseas governments
• members of non-Australian defence forces (and their dependants) stationed in Australia
• persons whose usual place of residence was outside Australia
• visitors
• persons living in very remote areas
• persons living in discrete Aboriginal and Torres Strait Islander communities.
   

8 The GSS was designed to provide reliable estimates at the national level and for each State and Territory. The sample was therefore spread across the states and territories in order to produce estimates that have a relative standard error (RSE) of no greater than 10% for characteristics that are relatively common in the national population (that at least 10% of the population would possess).

9 For the 2014 cycle, in order to be consistent with the aim of exploring the relative outcomes of people more vulnerable to socio-economic disadvantage, the sampling methodology was adapted to target sample from low socio-economic areas. People in these areas had a higher probability of being selected in the sample. Households were then randomly selected from each selected area to participate in the survey.

10 The initial sample for the survey consisted of approximately 18,574 private dwellings. This number was reduced to approximately 16,145 dwellings due to the loss of households which had no residents in scope for the survey and where dwellings proved to be vacant, under construction or derelict. Of the eligible dwellings, 80.1% responded fully (or adequately) which yielded a total sample from the survey of 12,932 dwellings.

11 Some survey respondents provided most of the required information, but were unable or unwilling to provide a response to certain data items. The records for these persons were retained in the sample and the missing values were recorded as 'don't know or not stated'. No attempt was made to deduce or impute for these missing values.

12 ABS Interviewers conducted personal interviews using a Computer Assisted Interviewing (CAI) questionnaire at selected dwellings during the period March to June 2014. CAI involves the use of a notebook computer to record, store, manipulate and transmit the data collected during interviews.

13 Much of the detail obtained from the GSS was provided by one person aged 15 years or over, randomly selected from each participating household. The random selection of this person was made once basic information had been obtained about all household members. Some financial and housing items collected in the GSS required the selected person to answer on behalf of other members of the household. In some cases, particularly where household information was not known by the selected person, a spokesperson for the household was nominated to provide household information.

14 Weighting is the process of adjusting results from a sample survey to infer results for the total in-scope population whether that be persons or households. To do this, a 'weight' is allocated to each sample unit i.e. a person or a household. The weight is a value which indicates how many population units are represented by the sample unit. 

15 The first step in calculating weights for each person or household is to assign an initial weight, which is equal to the inverse of the probability of being selected in the survey. For example, if the probability of a person being selected in the survey was 1 in 600, then the person would have an initial weight of 600 (that is, they represent 600 people).

16 The initial weights are then calibrated to align with independent estimates of the population of interest, referred to as 'benchmarks'. Weights calibrated against population benchmarks ensure that the survey estimates conform to the independently estimated distribution of the population 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 persons which may occur due to either the random nature of sampling or non-response. 

17 The GSS was benchmarked to the in scope estimated resident population (ERP) and the estimated number of households in the population. The 2014 GSS used population and household benchmarks based on the 2011 Census.

18 Given that the GSS did some targeting towards low socio-economic areas, further analysis was undertaken to ascertain whether benchmark variables, in addition to geography, age, and sex, should be incorporated into the weighting strategy. Analysis showed that the standard weighting approach did not adequately compensate for differential undercoverage in the 2014 GSS sample for SEIFA, when compared to other ABS surveys. As this variable was considered to have possible association with social characteristics, an additional benchmark was incorporated into the weighting process.

19 The benchmarks used in the calibration of final weights for the 2014 GSS were:

• state by part of state by age by sex
• SEIFA.
   

• state by part of state by household composition
• SEIFA.
   

20 Survey estimates of counts of persons are obtained by summing the weights of persons or households with the characteristic of interest. Estimates for means, such as mean age of persons, are obtained by summing the weights of persons in each category (e.g. individual ages), multiplying by the value for each category, aggregating the results across categories, then dividing by the sum of the weights for all persons. 

21 The majority of estimates shown in this publication are based on benchmarked person weights.

22 For more information about the collection of the data, please refer to the Explanatory Notes of General Social Survey: Summary Results, Australia, 2014.

23 Care has been taken to ensure that the results of this survey are as accurate as possible. All interviews were conducted by trained ABS Interviewers. Extensive reference material was developed for use in the field enumeration and intensive training was provided to interviewers in both classroom and on-the-job environments. There remain, however, other factors which may have affected the reliability of results, and for which no specific adjustments can be made. The following factors should be considered when interpreting these estimates:

• Information recorded in this survey is essentially 'as reported' by respondents, and hence may differ from information available from other sources or collected using different methodologies. Responses may be affected by imperfect recall or individual interpretation of survey questions.
• Some respondents may have provided responses that they felt were expected, rather than those that accurately reflected their own situation. Every effort has been made to minimise such bias through the development and use of culturally appropriate survey methodology.
   

24 GSS relies on self-reporting of diagnosed mental health conditions. That is, people who reported they had ever been told by a doctor or nurse that they have a mental health condition that has lasted or is expected to last 6 months or more. While not providing a prevalence measure, information obtained is valuable for comparing population characteristics of people with/without a mental health condition within the particular survey in which it has been used. Mental health conditions such as depression or feeling depressed, feeling anxious or nervous, behavioural and emotional disorders, problems learning or understanding things or dependence on drugs or alcohol were included.

25 The Survey of Mental Health and Wellbeing (SMHWB) is the best ABS source of information on the prevalence of mental health conditions in Australians aged 16-85 years. The SMHWB is different from other surveys collecting mental health data because it does not rely on self-reporting. Rather, it uses diagnostic assessment criteria to assess the lifetime, and 12-month prevalence, of selected mental disorders through the measurement of symptoms and their impact on day to day activities. The survey was based on a widely used international survey instrument (World Mental Health Survey Initiative version of the World Health Organization Composite International Diagnostic Interview, version 3.0), but tailored for the Australian context.

26 Homelessness in this publication refers to whether a person has ever previously been without a 'permanent place to live' for reasons other than one (or more) of the following: saving money; work related reasons; building or renovating their home; travelling/on holiday; house-sitting or having just moved back to a town or city. People who had ever previously been without a permanent place to live for other reasons (e.g. family/relationship breakdowns, financial problems, tight rental/property markets etc.) were counted in the survey as having had an experience of homelessness.

27 As the GSS only enumerates usual residents of private dwellings, it will not include: people currently living in shelters; people sleeping rough; people 'couch surfing' (staying temporarily with other households); nor people staying in boarding houses. It may include some people staying in Transitional Housing Management (THM) properties, if the adult staying there at the time of the survey considered that it was their usual residence at that time (THMs have been included in researcher estimates of the homeless). The GSS does not attempt to measure the prevalence of homelessness in Australia. Instead the survey sought information about a person's previous experience of being without a permanent place to live. That is, whether a person has ever experienced being without a permanent place to live at some point in their lives.

28 The statistics presented in this publication on episodes of homelessness differ from counts in the 2011 Census of Population and Housing. See Census of Population and Housing: Estimating homelessness, 2011 for more information.

29 Occupation data were classified according to the Australian ANZSCO - Australian and New Zealand Standard Classification of Occupations, 2013, Version 1.2 (cat. no. 1220.0).

30 Area data (Capital city, Balance of state/territory; Remoteness areas) are classified according to the Australian Statistical Geography Standard (ASGS).

31 Education data were classified according to the Australian Standard Classification of Education, 2001 (cat. no. 1272.0)

32 ABS publications draw extensively on information provided freely by individuals, businesses, government 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.