Notes on the data: ABORIGINAL AND TORRES STRAIT ISLANDER PSYCHOLOGICAL DISTRESS

Estimated Aboriginal population, aged 18 years and over, with psychological distress based on the Kessler 5 Scale (K5), 2018–19

Policy context: Mental health is fundamental to the wellbeing of individuals, their families and the population as a whole. One indication of the mental health and wellbeing of a population is provided by measuring levels of psychological distress using the Kessler Psychological Distress Scale-10 items (K10). The K10 questionnaire was developed to yield a global measure of psychological distress, based on ten questions about people's level of nervousness, agitation, psychological fatigue and depression in the four weeks prior to interview, asked of respondents 18 years and over [1]. Based on previous research, a very high K10 score may indicate a need for professional help [2]. The Kessler 5 (K5) score is used in the National Aboriginal and Torres Strait Islander Health Survey (NATSIHS) and is derived from a modified version of the K10. It uses five questions (instead of 10), and is designed for use in surveys of Aboriginal and Torres Strait Islander peoples [3].

In 2018–19, 30.8% of Aboriginal people reported experiencing ‘high’ or ‘very high’ levels of psychological distress, proportionally more females than males (35.0% and 25.9% respectively). Two thirds (66.3%) of Aboriginal people reported experiencing ‘low’ or ‘moderate’ psychological distress [4].

References

Coombs T. Australian Mental Health Outcomes and Classification Network: Kessler-10 Training Manual. Sydney: NSW Institute of Psychiatry; 2005.
Australian Bureau of Statistics (ABS). National health survey: users' guide - electronic publication, 2007-08. (ABS Cat. no. 4364.0). Canberra: ABS; 2009.
Australian Bureau of Statistics (ABS). National Aboriginal and Torres Strait Islander Health Survey methodology. Canberra: ABS; 2019. Available from: https://www.abs.gov.au/methodologies/national-aboriginal-and-torres-strait-islander-health-survey-methodology/2018-19; last accessed 10 May 2022.
Australian Bureau of Statistics (ABS). National Aboriginal and Torres Strait Islander Health Survey, Australia, 2018–19. (ABS Cat. no. 4715.0). Canberra: ABS; 2019. Last accessed 10 May 2022.

Notes:

Modelled Estimates: Overview

National surveys like the 2018–19 NATSIHS are designed to measure population characteristics for Australia or for a large proportion of the Australian population such as for a state or territory. Due to sample size limitations, it is not possible to provide accurate measures of population characteristics at lower geographic levels. The survey sample size is often too small, resulting in high margins of error. To meet user demands for information at lower geographic levels, the Australian Bureau of Statistics (ABS) can produce modelled estimates. Modelled estimates use both the survey responses for NATSIHS, together with other information about the population of a geographic area gained from the Population Census and administrative data sources to build a predictive model that estimates a given characteristic for a small area. The term “small area” refers to a geographical area that is smaller than a state or territory, such as Indigenous Areas, Indigenous Regions and Primary Health Networks. Strictly speaking modelled estimates are not as reliable as directly estimated survey measures from the NATSIHS. Measures of error are provided with these estimates (in the data) and the Technical Appendix explains what types of error are present.

Modelled estimates can be used for observing national trends by using the complete set of modelled data for IAREs across Australia or a state/territory to support program evaluation or resource allocation or looking at trends across a range of IAREs. For example, looking at a range of areas in remote Australia or along the Eastern seaboard with high or low number or proportion of people with the selected characteristic. A modelled estimate for a single area on its own should be used with extreme caution. Models are limited by the input data. Often significant local information about particular small areas exists but has not been collected for all areas and cannot be incorporated into the models.

The ABS has used a number of methods to measure the quality of the estimates, one of which is the relative root mean squared error (RRMSE) of the modelled estimates. The RRMSEs are included with the data. Users are advised that:

estimates with RRMSEs less than 25% are considered reliable for most purposes;
estimates with RRMSEs from 0.25 and to 0.50 have been marked (~) to indicate that they should be used with caution; and
those greater than 0.50 but less than 1 are marked (~~) to indicate that the estimate is considered too unreliable for general use.

Modelled Estimates: Indigenous Areas and Indigenous Regions

Small area modelled estimates are produced by the ABS to provide users reliable estimates at a lower geographic level than State or Territory. Initially, the ABS produced a set of estimates from the 2018–19 NATSIHS for Indigenous Regions. PHIDU raised the possibility of having similar estimates for a selection of the variables at the (smaller) Indigenous Area level, for Indigenous Areas where the population was large enough and the particular variable had a sufficiently high proportion in the population. The ABS agreed, and it is the result of their further work that is presented here.

Where estimates could not be made for an Indigenous Area, as a result of its population size, the data for that Indigenous Area have been grouped with other, unpublished Indigenous Areas within the over-arching Indigenous Region, and a rate for the combined group calculated and published. Modelled estimates use both the survey responses from the NATSIHS, together with other information about the population of a geographic area gained from the Population Census and administrative data sources to build a predictive model that estimates a given characteristic for a small area. Details of the method used and accuracy of results are available from the ABS Explanatory Notes: Modelled estimates for small areas based on the 2018–19 National Aboriginal and Torres Strait Islander Health Survey

For the Indigenous Regions of Tasmania (IREG601) and Australian Capital Territory (IREG801), direct estimates were published instead of modelled estimates. Estimates for States and Territories, Greater Capital City Statistical Areas (GCCSA) and Remoteness Areas are also direct estimates, extracted using the ABS TableBuilder.

Indicator detail

Information was collected from respondents aged 18 years and over using the Kessler Psychological Distress Scale-5 (K5), a modified version of the Kessler Psychological Distress Scale-10 (K10) designed for use in surveys of Aboriginal and Torres Strait Islander people. This modified 5 item questionnaire yields a measure of psychological distress based on questions about negative emotional states (with different degrees of severity) experienced in the four weeks prior to interview. For each question, there is a five-level response scale based on the amount of time that a respondent experienced those particular feelings. The response options are 'none of the time'; 'a little of the time'; 'some of the time'; 'most of the time'; or 'all of the time'. Each of the items are scored from 1 for 'none' to 5 for 'all of the time'. Scores for the five items are summed, yielding a minimum possible score of 5 and a maximum possible score of 25, with low scores indicating low levels of psychological distress and high scores indicating high levels of psychological distress.

K5 results from the 2018–19 NATSIHS are grouped into the following two levels of psychological distress: 'low/moderate' (scores of 5-11, indicating moderate, little or no psychological distress) and 'high/very high' (scores of 12-25). Based on research from other population studies, a 'very high' level of psychological distress shown by the K10 may indicate a need for professional help. In this atlas, data are published for respondents aged 18 years and over who scored in the ‘low/moderate’ or ‘high/very high’ levels of psychological distress.

Geography: Data available by Indigenous Area (including Indigenous Region) and Remoteness Area

Numerator: Total Aboriginal population aged 18 years and over assessed as having a low or moderate/ high or very high level of psychological stress under the K5

Denominator: Aboriginal population aged 18 years and over

Detail of analysis: Indirectly age-standardised rate per 100 population (aged 18 years and over); and/or indirectly age-standardised ratio, based on the Australian standard

Source:

Indigenous Areas: Age-standardised rates are based on Australian Bureau of Statistics data, produced for PHIDU, from the 2018–19 National Aboriginal and Torres Strait Islander Health Survey.

Indigenous Regions: Age-standardised rates are based on Australian Bureau of Statistics data from the 2018–19 National Aboriginal and Torres Strait Islander Health Survey: Small Area Estimates, Australia (ABS Cat. no. 4715.0).

Remoteness Areas: Compiled by PHIDU based on direct estimates from the 2018–19 National Aboriginal and Torres Strait Islander Health Survey, ABS TableBuilder.