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2 Results in this publication are from either a combined data file of both the NATSIHS and NATSINPAS, referred to as the AATSIHS Core, or from the NATSINPAS only. The combined sample size of the AATSIHS Core (12,947 Aboriginal and Torres Strait Islander people) is around 3.2 times the 2012-13 NATSINPAS sample and may therefore produce more accurate estimates. However, the AATSIHS Core sample only contains those data items common to both NATSIHS and NATSINPAS, and therefore does not provide the full spectrum of data items from the AATSIHS. As a result, items for adults, pedometer and 2-4 year olds has been sourced from NATSINPAS only. For more information see: The Structure of the AATSIHS
4 The AATSIHS Core incorporated surveys which were conducted throughout Australia from April 2012 to July 2013. The NATSINPAS component was conducted throughout Australia from August 2012 to July 2013. The NATSIHS collected similar data on adult physical activity as NATSINPAS, of which level of exercise was reported in the Australian Aboriginal and Torres Strait Islander Health Survey: First Results, 2012-13 (cat no. 4727.0.55.001).
5 This publication contains information about physical activity (including pedometer steps) and sedentary behaviour (in particular screen-based activity, household rules and screen-based equipment) and comparisons with:
6 Throughout this release, the term 'Aboriginal and Torres Strait Islander people' refers to all persons who identified themselves as being of Aboriginal, Torres Strait Islander, or both Aboriginal and Torres Strait Islander origin.
8 Explanations of terms and concepts are provided in the Glossary and a list of data items currently available from the survey can be found in the Australian Aboriginal and Torres Strait Islander Health Survey: Users’ Guide, 2012-13 (cat no. 4727.0.55.002), referred to throughout this publication as the 'Users' Guide'.
SCOPE AND COVERAGE OF THE SURVEY
9 The AATSIHS Core contains a sample of 8,237 private dwellings across Australia, while the NATSINPAS contains a sample of 2900 private dwellings. Private dwellings are houses, flats, home units and any other structures used as private places of residence at the time of the survey. People usually resident in non-private dwellings, such as hotels, motels, hostels, hospitals, nursing homes, and short-stay caravan parks were not in scope.
10 The scope of the AATSIHS Core and NATSINPAS was all Aboriginal and Torres Strait Islander people who were usual residents of private dwellings in Australia. Usual residents are those who usually live in a particular dwelling and regard it as their own or main home.
11 Further scope exclusions for these surveys were:
13 The AATSIHS Core and NATSINPAS were conducted in remote and non-remote areas in all states and territories of Australia, including discrete Aboriginal and Torres Strait Islander communities.
14 Coverage exclusions apply to those people who were part of the in-scope population, but who were not included in the sampling frame as a result of managing enumeration costs. The sample was based on where Aboriginal and Torres Strait Islander households were identified in the 2011 Census of Population and Housing. Coverage exclusions applied included:
16 The estimated resident Aboriginal and Torres Strait Islander population aged 2 years and over living in private and non-private dwellings at 30 June 2011 was 636,945. Excluding persons in non-private dwellings, there were 606,915 Aboriginal and Torres Strait Islander people aged 2 years and over.
17 Population benchmarks, which align with the survey scope, are based on the most recently released Estimated Resident Aboriginal and Torres Strait Islander Population (ERP), which in this case are for 30 June 2011. The ERP data are based on the 2011 Census of Population and Housing, adjusted by the 2011 Post-Enumeration Survey (PES). More information about the Estimated Resident Aboriginal and Torres Strait Islander Population can be found in Estimates of Aboriginal and Torres Strait Islander Australians, June 2011 (cat. no. 3238.0.55.001).
18 The AATSIHS Core approached 10,362 households, after sample loss. Of these, 8,237 (or 80%) were fully or adequately responding, yielding a total sample for the survey of 12,947 persons (aged 2 years and over). The NATSINPAS approached 3,661 households after sample loss. Of these, 2,900 (79%) were fully or adequately responding, yielding a total sample for the survey of 4,109 persons (aged 2 years and over).
FINAL PERSONS IN SAMPLE
20 More information on response rates is available in the Users' Guide.
21 Trained ABS interviewers conducted personal interviews with selected residents in sampled dwellings. Selected persons aged 18 years and over in each dwelling were interviewed about their own health characteristics. An adult, nominated by the household, was interviewed for selected children (aged 2 years and over) in the household. Selected children aged 15-17 years may have been personally interviewed with parental consent. An adult, nominated by the household, was also asked to provide information about the household, such as the combined income of other household members. Children aged 6-14 years were encouraged to be involved in the survey, particularly for the physical activity module (see Child Physical Activity (5 to 17 years) chapter in the Users' Guide).
27 To take account of language and cultural differences in community areas, the collection method varied for remote and non-remote areas. Some questions for remote areas, for example the physical activity module, were reworded to enhance respondent understanding of the concepts. Additionally, the survey content in remote areas excluded questions for which data quality was considered problematic to collect or not applicable.
28 More information on data collection and a copy of the survey questionnaires are provided in the Users' Guide.
WEIGHTING, BENCHMARKING AND ESTIMATION
29 Weighting is a process of adjusting results from a sample survey to infer results for the in-scope total population. To do this, a weight is allocated to each sample person. The weight is a value which indicates how many population units are represented by the sample unit.
30 The first step in calculating weights for each person 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 being selected in the survey was 1 in 45, then the person would have an initial weight of 45 (that is, they would represent 45 people).
31 The weights were separately calibrated to 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 distributions 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 (e.g. age, sex, remoteness), which may occur due to either the random nature of sampling, non-response, non-identification or various other factors.
33 Estimates of counts of persons are obtained by summing person weights of persons with the characteristic of interest. The estimates presented in this release are based on benchmarked person weights.
34 More information on weighting, benchmarking and estimation is provided in the Users' Guide.
RELIABILITY OF ESTIMATES
35 All sample surveys are subject to error which can be broadly categorised as either sampling error or non-sampling error.
36 Sampling error is the difference between estimates, derived from a sample of persons, and the value that would have been produced if all persons in scope of the survey had been included. For more information refer to the Technical Note. Indications of the level of sampling error are given by the Relative Standard Error (RSE) and Margin of Error (MoE).
37 In this publication, estimates with an RSE of 25% to 50% are preceded by an asterisk (e.g. *3.4) to indicate that the estimate has a high level of sampling error relative to the size of the estimate, and should be used with caution. Estimates with an RSE over 50% are indicated by a double asterisk (e.g. **0.6) and are generally considered too unreliable for most purposes. These estimates can be used to aggregate with other estimates to reduce the overall sampling error.
38 MoEs, calculated at the 95% confidence level, are provided for all proportion estimates to assist users in assessing the reliability of these types of estimates. Users may find this measure more convenient to use than the RSE, in particular for small and large proportions. The estimate combined with the MoE defines a range which is expected to include the true population value with a given level of confidence. This is known as the confidence interval. This range should be considered by users to inform decisions based on the estimate. In this publication, proportions with a MoE greater than 10 percentage points are preceded by a hash (e.g. #71.3).
39 Non-sampling error may occur in any data collection, whether it is based on a sample or a full count (e.g. Census). Non-sampling error may occur at any stage throughout the survey process. For example, persons selected for the survey may not respond (non-response); survey questions may not be clearly understood by the respondent; responses may be incorrectly recorded by interviewers; or there may be errors in coding or processing data.
41 Analysis was also undertaken, where appropriate, to compare the characteristics of respondents to the AATSIHS Core and the NATSINPAS with a number of ABS collections to ascertain data consistency. Sources for comparison included:
42 Undercoverage is the shortfall between the population represented by the achieved sample and the in-scope population. Weighting, as described in paragraphs 29 to 34 adjusts for undercoverage, reducing the under-coverage bias in estimates.
44 It is usual for ABS Aboriginal and Torres Strait Islander surveys to have large levels of undercoverage. The AATSIHS Core and the NATSINPAS undercoverage rate was 63% of the in-scope population at the national level. However, 6% of this is due to planned frame exclusions and overlap with the Monthly Population Survey where analysis has shown that the impact of any bias is minimal. For comparison, the estimated undercoverage in the 2004–05 NATSIHS and the 2008 NATSISS was 42% and 53% respectively.
45 The NATSINPAS rate varies across states and territories, with Vic (78%), NT (72%) and NSW (68%) recording the highest rates of undercoverage compared with the lowest undercoverage rates in Tas (6%) and ACT (44%). AATSIHS Core rates can be found in the Users' Guide.
47 The classifications used to describe adult and child physical activity in this publication used the same classifications as in NNPAS, which were developed based on other ABS surveys:
51 Some techniques used to guard against identification or disclosure of confidential information in statistical tables are suppression of sensitive cells, random adjustments to cells with very small values, and aggregation of data. To protect confidentiality within this publication, some cell values may have been suppressed and are not available for publication but included in totals where applicable. As a result, sums of components may not add exactly to totals due to the confidentialisation of individual cells.
52 Estimates presented in this publication have been rounded. As a result, sums of components may not add exactly to totals.
53 For physical activity data in this publication, minutes and average number of steps are reported as whole numbers. All other units in the data are reported to one decimal place.
54 Proportions presented in this publication are based on unrounded figures. Calculations using rounded figures may differ from those published.
55 The AATSIHS Core and the NATSINPAS was dependent on the high level of cooperation received from Aboriginal and Torres Strait Islander peoples and their communities. Without their continued cooperation, the wide range of Aboriginal and Torres Strait Islander 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.
PRODUCTS AND SERVICES
56 Further Australian Aboriginal and Torres Strait Islander Health Survey (AATSIHS) publications are planned for release. For more information see Release schedule.
57 Information from the AATSIHS Core and the NATSINPAS will be returned to Aboriginal and Torres Strait Islander people through the ABS State and Territory Statistical Services (STSS) Program and collaborations with other organisations.
58 Special tabulations based on the data from this survey are available on request. Subject to confidentiality and sampling variability constraints, tabulations can be produced from the survey to meet individual requirements. These can be provided in electronic or printed form.
61 Other ABS publications which may be of interest are shown under the 'Related Information' tab of this release.
62 Current publications and other products released by the ABS are listed on the ABS website <www.abs.gov.au>. The ABS also issues a daily Release Advice on the website which details products to be released in the week ahead.
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