INTRODUCTION
1 This publication presents information on the use of health services and the actions people take for their health from the 2014-15 National Health Survey (NHS).
2 The 2014-15 NHS also collected information about:
- the health status of the population, including long-term health conditions experienced;
- health-related aspects of people's lifestyles, such as smoking, Body Mass Index, diet, exercise and alcohol consumption; and
- demographic and socioeconomic characteristics.
3 See the National Health Survey: First Results, 2014-15 (
cat. no. 4364.0.55.001) for other findings from the 2014-15 NHS.
SCOPE OF THE SURVEY
4 The NHS was conducted from a sample of approximately 14,700 private dwellings across Australia.
5 Urban and rural areas in all states and territories were included, while Very Remote areas of Australia and discrete Aboriginal and Torres Strait Islander communities (and the remainder of the Collection Districts in which these communities were located) were excluded. These exclusions are unlikely to affect national estimates, and will only have a minor effect on aggregate estimates produced for individual states and territories, excepting the Northern Territory where the population living in Very Remote areas accounts for around 23% of persons.
6 Non-private dwellings such as hotels, motels, hospitals, nursing homes and short-stay caravan parks were excluded from the survey. This may affect estimates of the number of people with some long-term health conditions (for example, conditions which may require periods of hospitalisation).
7 Within each selected dwelling, one adult (aged 18 years and over) and one child (0-17 years) were randomly selected for inclusion in the survey. This sub-sampling within households enabled more information to be collected from each respondent than would have been possible had all usual residents of selected dwellings been included in the survey. For the purposes of the NHS, a household was defined as one or more persons, at least one of whom is aged 18 years and over, usually resident in the same private dwelling.
8 The following groups were excluded from the survey:
- certain diplomatic personnel of overseas governments, customarily excluded from the Census and estimated resident population;
- persons whose usual place of residence was outside Australia;
- members of non-Australian Defence forces (and their dependents) stationed in Australia; and
- visitors to private dwellings.
SAMPLE DESIGN
9 Dwellings were selected at random using a multistage area sample of private dwellings. The initial sample selected for the survey consisted of approximately 21,850 dwellings. This was reduced to a sample of 17,958 after sample loss (for example, households selected in the survey which had no residents in scope of the survey, vacant or derelict buildings, buildings under construction). Of those remaining dwellings, 14,723 (or 82.0%) were fully or adequately responding, yielding a total sample for the survey of 19,259 persons.
APPROACHED SAMPLE, FINAL SAMPLE AND RESPONSE RATES
|
 | NSW | Vic. | Qld | SA | WA | Tas. | NT | ACT | Aust. |
|
| Households approached (after sample loss) | 3 246 | 3 196 | 2 796 | 2 224 | 2 250 | 1 640 | 1 131 | 1 475 | 17 958 |
| Households in sample | 2 499 | 2 547 | 2 367 | 1 916 | 1 865 | 1 497 | 775 | 1 265 | 14 723 |
| Response rate (%) | 77.0 | 79.7 | 84.7 | 86.2 | 82.9 | 91.3 | 68.5 | 85.8 | 82.0 |
 |  |  |  |  |  |  |  |  |  |
| Persons in sample | 3 272 | 3 335 | 3 081 | 2 434 | 2 450 | 1 918 | 1 057 | 1 708 | 19 259 |
|
10 To take account of possible seasonal effects on health characteristics, the sample was spread randomly across a 12-month enumeration period. Analysis of previous health surveys has shown no particular seasonal bias across key estimates.
DATA COLLECTION
11 Trained ABS interviewers conducted personal interviews with selected residents in sampled dwellings. One adult (aged 18 years and over) in each dwelling was selected and interviewed about their own health characteristics as well as information about the household (for example, income of other household members). An adult, nominated by the household, was interviewed about one child in the household. Some children aged 15-17 years may have been personally interviewed with parental consent.
WEIGHTING, BENCHMARKING AND ESTIMATION
12 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 unit; for example, a household or a person. The weight is a value which indicates how many population units are represented by the sample unit.
13 The first step in calculating weights for each person was to assign an initial weight, which was 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 others). An adjustment was then made to these initial weights to account for the time period in which a person was assigned to be enumerated.
14 The weights are calibrated to align with independent estimates of the population of interest, referred to as 'benchmarks', in designated categories of sex by age by area of usual residence. Weights calibrated against population benchmarks in this way compensate for over or under-enumeration of particular categories of persons and ensure that the survey estimates conform to the independently estimated distribution of the population by age, sex and area of usual residence, rather than to the distribution within the sample itself.
15 The NHS was benchmarked to the estimated resident population living in private dwellings in non-Very Remote areas of Australia at 31 December 2014. Excluded from these benchmarks were persons living in discrete Aboriginal and Torres Strait Islander communities. The benchmarks, and hence the estimates from the survey, do not (and are not intended to) match estimates of the total Australian resident population (which include persons living in Very Remote areas or in non-private dwellings, such as hotels) obtained from other sources.
16 Survey estimates of counts of persons are obtained by summing the weights of persons with the characteristic of interest. Estimates of non-person counts (for example, number of health conditions) are obtained by multiplying the characteristic of interest with the weight of the reporting person and aggregating.
RELIABILITY OF ESTIMATES
17 All sample surveys are subject to sampling and non-sampling error.
18 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. Indications of the level of sampling error are given by the Relative Standard Error (RSE) and 95% Margin of Error (MOE).
19 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.
20 Margins of Error are provided for proportions to assist users in assessing the reliability of these data. The proportion 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 proportion. Proportions with an MOE of greater than 10 percentage points are preceded by a hash (e.g. #40.1) to indicate the range in which the true population value is expected is relatively wide.
21 Non-sampling error may occur in any data collection, whether it is based on a sample or a full count such as a census. Non-sampling errors occur when survey processes work less effectively than intended. Sources of non-sampling error include non-response, errors in reporting by respondents or in recording of answers by interviewers, and errors in coding and processing data.
22 Non-response occurs when people are unable to or do not cooperate, or cannot be contacted. Non-response can affect the reliability of results and can introduce a bias. The magnitude of any bias depends on the rate of non-response and the extent of the difference between the characteristics of those people who responded to the survey and those who did not.
23 In the 2014-15 NHS, measurements of height, weight and waist circumference were taken of respondents aged 2 years and over, while blood pressure was also measured for adult respondents (aged 18 years and over). While these items had relatively high non-response rates, analysis indicated no bias existed in the non-responding population. Imputation has been used to obtain values for respondents for whom physical measurements were not taken. For more information see
Appendix 2: Physical measurements in the 2014-15 National Health Survey.
24 The following methods were adopted to reduce the level and impact of non-response:
- face-to-face interviews with respondents;
- the use of proxy interviews in cases where language difficulties were encountered, noting the interpreter was typically a family member;
- follow-up of respondents if there was initially no response; and
- weighting to population benchmarks to reduce non-response bias.
25 For more information see
Technical Note - Reliability of Estimates.
INTERPRETATION OF RESULTS
26 Care has been taken to ensure that results are as accurate as possible. This includes thorough design and testing of the questionnaire, interviews being conducted by trained ABS Interviewers, and quality control procedures throughout data collection, processing and output. 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 the survey is essentially 'as reported' by respondents, and hence may differ from information available from other sources or collected using different methodology; for example, information about health conditions is self-reported and, while not directly based on a diagnosis by a medical practitioner in the survey, respondents were asked whether they had ever been told by a doctor or nurse that they had a particular health condition. Conditions which have a greater effect on people's wellbeing or lifestyle, or those specifically mentioned in survey questions, are expected in general to have been better reported than others;
- 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 appropriate survey methodology.
Comparability with Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002)
27 Data relating to health service usage and health related actions for 2014-15 are generally comparable with the same data from 2011-12. However there are some exceptions or issues to be aware of:
Breastfeeding
- The population of interest for breastfeeding was changed between 2011-12 and 2014-15 for most data items from children aged 0-3 years, to children aged 0-24 months. Data for 'Whether ever received breastmilk' and 'Age first ate any soft or semi solid or solid food' are comparable to 2011-12 for all persons 0-3 years old. Data for 'Currently receiving breastmilk' and 'Age stopped receiving any breastmilk' are comparable between 2011-12 and 2014-15, but only for children aged 0-24 months.
- Exclusive breastfeeding data items are not comparable to 2011-12. Firstly, they were only asked of those aged 0-24 months of age. Secondly, while the 2011-12 questionnaire included separate and specific probing about water, fruit juices and other liquids, the 2014-15 questionnaire included these items on a prompt card only for those aged 0-24 months who were currently receiving breast milk (ie. not those aged 0-24 months who had stopped receiving breast milk).
Arthritis
- There are no known issues of comparability to Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002). There are issues regarding the comparability between 2011-12 and 2014-15 of 'Gout' and 'Rheumatism' (for further information see the Explanatory Notes of National Health Survey: First Results, 2014-15 (cat. no. 4364.0.55.001)), however these are not included within the definition of arthritis as used in this publication: "Arthritis is characterised by an inflammation of the joints often resulting in pain, stiffness, disability and deformity."
Asthma
- There are no known issues of comparability to Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002).
Cancer
- There are no known issues of comparability to Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002).
Diabetes mellitus
- In this publication, data on diabetes refers to persons who reported having been told by a doctor or nurse that they had diabetes, irrespective of whether the person considered their diabetes to be current or long-term, unless otherwise stated. This definition was first used for estimates of diabetes in Australian Health Survey: Updated Results, 2011-12 (cat. no. 4364.0.55.003). In earlier publications, including Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002), persons who had reported having diabetes, but that it was not current, were not included.
Diseases of the circulatory system
- 'Heart, stroke and vascular disease', a component within diseases of the circulatory system, has been redefined to include persons who reported having ischaemic heart diseases and cerebrovascular diseases that were not current and long-term at the time of interview. Data published in Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002) excluded these persons. However, estimates of diseases of the circulatory system for 2011-12 and 2014-15 in this publication included these persons.
Hypertension
Kidney disease
- There are no known issues of comparability to Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002).
Mental and behavioural conditions
Osteoporosis
- There are no known issues of comparability to Australian Health Survey: Health Service Usage and Health Related Actions, 2011-12 (cat. no. 4364.0.55.002).
Comparability with National Health Survey: First Results, 2014-15 (cat. no. 4364.0.55.001)
28 Data are generally comparable with those from 2014-15 First Results
with some exceptions or issues to be aware of:
Health actions taken for specific conditions
- Estimates of populations with specific long term health conditions within the datacubes of this publication may not match estimates from National Health Survey: First Results, 2014-15 (cat. no. 4364.0.55.001). Due to the design of the survey, not all people with a condition may have been asked about actions taken for their condition. When referring to the total populations with specific conditions within the commentary of this publication, the estimates from National Health Survey: First Results, 2014-15 (cat. no. 4364.0.55.001) have been used. However the proportions in the commentary and datacubes of this publication, unless otherwise stated, are based on a denominator of only the population who were asked questions about actions taken for, or due to, their specific condition. This is the case for arthritis, cancer, diabetes mellitus, hypertension, kidney disease, osteoporosis and diseases of the circulatory system.
Comparability between 2014-15 National Health Survey (NHS) and Patient Experience Survey
While similar data items between the two surveys do broadly follow similar trends Estimates from the National Health Survey may differ from those obtained from other surveys (such as the Patient Experience Survey, General Social Survey and Survey of Disability, Ageing and Carers) due to differences in survey mode, methodology and questionnaire design.
CLASSIFICATIONS
29 Long-term health conditions reported by respondents in the NHS are presented using a classification originally developed for the 2001 NHS by the Family Medicine Research Centre, University of Sydney, in conjunction with the ABS. The classification is based on the 10th revision of the International Classification of Diseases (ICD) and is used for all years from 2001 to 2014-15.
30 Country of birth was classified to the Standard Australian Classification of Countries (cat. no. 1269.0).
31 Main language spoken at home was classified according to the Australian Standard Classification of Languages (cat. no. 1267.0).
32 Descriptions for data items such as Body Mass Index and the Kessler Psychological Distress Scale (K10) are included in the Glossary to this publication.
CONFIDENTIALITY
33 The Census and Statistics Act, 1905 provides the authority for the ABS to collect statistical information, and requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation. This requirement means that the ABS must take care and make assurances that any statistical information about individual respondents cannot be derived from published data.
34 To minimise the risk of identifying individuals in aggregate statistics, a technique known as perturbation is used to randomly adjust cell values. Perturbation involves a small random adjustment of the statistics and is considered the most satisfactory technique for avoiding the release of identifiable statistics while maximising the range of information that can be released. These adjustments have a negligible impact on the underlying pattern of the statistics. After perturbation, a given published cell value will be consistent across all tables. However, adding up cell values to derive a total will not necessarily give the same result as published totals.
35 Perturbation has been applied to 2014–15 data. Data from previous NHS presented in this publication have not been perturbed, but have been confidentialised if required using suppression of cells.
ROUNDING
36 Estimates presented in this publication have been rounded.
37 Proportions presented in this publication are based on unrounded figures. Calculations using rounded figures may differ from those published.
ACKNOWLEDGEMENTS
38 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.
PRODUCTS AND SERVICES
39 Summary results from the NHS 2014-15 are available in spreadsheet form from the 'Downloads' tab in National Health Survey: First Results, 2014-15 (cat. no. 4364.0.55.001). The statistics presented are only a selection of the information collected.
40 For users who wish to undertake more detailed analysis, microdata products are available from all National Health Surveys, including 2014-15. These include Basic and Expanded CURFs as well as TableBuilder products. TableBuilder is an online tool for creating tables from ABS survey data, where variables can be selected for cross-tabulation. It has been developed to complement the existing suite of ABS microdata products and services including Census TableBuilder and CURFs. Further information about ABS microdata, including conditions of use, is available via the Microdata section on the ABS website.
41 Customised tabulations are available on request. Subject to confidentiality and sampling variability constraints, tabulations can be produced from the survey incorporating data items, populations and geographic areas selected to meet individual requirements.
RELATED PUBLICATIONS
42 Other ABS publications which may be of interest are shown under the 'Related Information' tab of this release.
43 Current publications and other products released by the ABS are listed on the ABS website. 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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