Technical notes

About the ABS National Health Survey

This web report contains results from the Australian Bureau of Statistics (ABS) National Health Survey (NHS) 2017–18, collected between July 2017 to June 2018.

The 2017–18 NHS is the most recent in a series of Australia-wide health surveys conducted by the ABS. It was designed to collect a range of information about the health of Australians, including:

  • prevalence of long-term health conditions
  • health risk factors such as smoking, overweight and obesity, alcohol consumption and exercise
  • use of health services such as consultations with health practitioners and actions people have recently taken for their health
  • demographic and socioeconomic characteristics.

The 2017–18 NHS collected data on children and adults living in private dwellings but excluded persons living in non-private dwellings, very remote areas and discrete Aboriginal and Torres Strait Islander communities.

For further information, refer to the ABS National Health Survey: First Results, 2017–18.

Primary Health Network data

This release includes the following indicator by Primary Health Network (PHN):

  • Number of adults who were classified as overweight or obese (by categories .

Proportions have been age standardised to the 2001 Australian population to account for differences in the age structure of the population for different areas.

Results are presented as both crude and age-standardised rates.

Participants were included in the analysis if they were aged 18 years and over.

Body mass index (BMI) is a common measure for classifying a person as underweight, normal weight, overweight or obese. BMI scores were calculated as weight (kg) divided by height in metres, squared (m2). Consenting participants in the ABS NHS 2014–15 were measured using digital scales for their weight and a stadiometer for their height.

Participants with a BMI equal to or greater than 25 and less than 30 were classified as overweight. Those with a BMI equal to or greater than 30 were classified as obese.

In 2017-18, 33.8% of respondents aged 18 years and over did not have their height and or weight measured. For these respondents, imputation was used to obtain a BMI. For more information see Appendix 2: Physical measurements in the 2017-18 National Health Survey (ABS 2018).

About the data

Primary Health Networks (PHNs) are local organisations that connect health services across a specific geographic area, with the boundaries defined by the Australian Government Department of Health.

The quality of estimates from the NHS can vary across PHN areas, as the survey was not specifically designed to produce estimates at this level of geography.

As an indication of the accuracy of proportions, 95% confidence intervals were produced. These were calculated by the ABS using relative standard error (RSE) estimates of the proportion.

To ensure robust reporting of these data by PHN areas, suppression or interpret with caution rules were developed and applied by the Australian Institute of Health and Welfare.

Estimates of a percentage or its complement that had a relative standard error greater than 50% were suppressed. These estimates were considered unreliable for most practical purposes.

Data for PHN areas were suppressed if there was the likelihood of a non-representative sample, that is, where the survey sample count in the PHN area was less than 20% of the expected number of adults.

The ‘interpret with caution’ flag was applied to the data if the relative standard error associated with the percentage or its complement was greater than 25%. This indicates the proportion derived is subject to high sampling error and should be used with caution.

Data for Northern Territory should be interpreted with caution as the NHS excluded discrete Aboriginal and Torres Strait Islander communities and very remote areas, which comprise around 28% of the estimated resident population of the Northern Territory.

Data quality statement

For more information about the ABS 2017–18 National Health Survey see:

4324.0.55.001 - Microdata: National Health Survey, 2017-18