4363.0 - National Health Survey: Users' Guide, 2014-15  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 31/07/2017   
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This topic refers to respondents' physical measurements and other self-perception questions including:

    • The height (cm), weight (kg) and waist circumference (cm) of respondents as measured during the interview
    • Body mass index (BMI) derived from the height and weight physical measurements
    • Self-perceived body mass.

Body Mass Index (BMI) or Quetelet's index is a useful tool, at a population level, for measuring trends in body weight and helping to define population groups who are at higher risk of developing long-term medical conditions associated with a high BMI, for example Type 2 diabetes and cardiovascular disease.

Waist circumference reflects mainly subcutaneous abdominal fat storage, and according to a World Health Organisation (WHO) joint report has been shown to positively correlate to disease risk. The scale used for determining risky waist circumference is as recommended by the World Health Organisation, (See Obesity: preventing and managing the global epidemic. Report of a WHO Consultation, 2000).


Physical measurements were obtained for all persons, excluding pregnant women, aged 2 years and over who agreed for the measurements to be taken. (See interpretation information re the exclusion of pregnant women.)

Self-perceived body mass was asked of all persons aged 15 years and over in the 2014-15 NHS. It was not asked where a proxy was reporting on behalf of the respondent.


Information about physical measurements was first published in the National Health Survey: First Results, 2014-15 based on a sample of 18,594 people aged 2 years and over. Additional information relating to physical measurements was also published in Health Service Usage and Health related Actions, Australia, 2014-15.

Physical Measurements

Physical measurements were taken towards the end of the survey. All physical measurements were voluntary, and women who volunteered at this point in the interview that they were pregnant were not measured. Interviewers used digital scales to measure weight (maximum 150kg), a stadiometer to measure height (maximum 210cm), and a metal tape measure (which avoided the risk of the tape stretching) to measure waist circumference (maximum 200cm). Thorough interviewer training identified the points at which waists were to be measured as recommended by a World Health Organisation report as well as how to take the measurements with the least amount of respondent discomfort. For waist measurements, interviewers held the end of the tape at the appropriate point and asked the respondent to turn around until the tape met, or asked the respondent to hold the end of the tape and walked around them until the tape met.

Interviewers encouraged respondents to remove their shoes and any heavy clothing, e.g. jumpers, before they took measurements, however, this was voluntary, and may not have occurred in some cases. Interviewers were not required to record if they thought clothing may have impacted significantly on measurements. Weight was recorded in kilos to one decimal point, and height and waist measurements were recorded in centimetres to one decimal point. Waist measurements were taken by placing the tape measure across the top of the belly button. If a respondent's waist measurement was more than two meters (the maximum measurement of the tape measure), interviewers were instructed to record this as 200.0cm. If a respondent's weight was self-reported to be more than 150 kilograms (the maximum measurement of the scales used) the interviewer was instructed to record 999.9 kg and include a comment in the instrument, however some interviewers recorded weights above 150kg and these records were included in output.

In order to validate the height and waist measurements, a random 10% of respondents were selected to be measured an additional time. If this second measurement of height or waist varied by more than one centimetre then a third reading was taken. Weight measurements were only taken once. For output purposes only the first measurement is used.

Body Mass Index

Body mass index (BMI) scores were derived using Quetelet's metric body mass index which is calculated as weight (kg) divided by height (m)2. BMI scores are commonly grouped for output. Whist the cut off points for different ethnic groups can vary, the World Health Organisation recommends that the same cut off points be used for international classification. The detailed output classifications available are shown in the table below. 2014-15 NHS publications use aggregated categories for estimates in published tables.

Category BMI score

Class 3 Less than 16
Class 2 16.0 to less than 17.0
Class 1 17.0 to less than 18.5
Normal range
NormalAdult: 18.5 to less than 20.0; Child: 18.5 to less than 25.0(a)
Normal (Adult only)20.0 to less than 25.0
25.0 to less than 30.0
Class 1Adult: 30.0 to less than 35.0; Child: 30.0 or more (a)
Class 2 (Adult only)35.0 to less than 40.0
Class 3 (Adult only)40 or more

(a) Child cut-offs identified in this table are in terms of Adult cut-offs. While the formula to calculate BMI scores is the same for adults and children, the classification of children's BMI is different to that of persons aged 18 years and over, and takes into account individual age and sex. BMI cut-off ranges for children 2 to 17 years of age are included in Appendix 4: Classification of BMI for Children. Half-year cut-off points are used to calculate children's BMI scores for persons aged 2 to 17. Two versions of the data item are available, one using the mid-year cut-off (used in the National Health Survey: First Results, 2014-15) and one using the whole-year cut-off.

Waist Circumference

Waist circumference reflects mainly subcutaneous abdominal fat storage, and according to a World Health Organisation (WHO) joint report has been shown to positively correlate to disease risk. The scale used for determining risky waist circumference is as recommended by the WHO, (See Obesity: preventing and managing the global epidemic. Report of a WHO Consultation, 2000). As with BMI, the cut-off points in this scale are designed for people of European origin. However, as ethnicity cannot be determined, the same cut-off points are used for all respondents.

Waist circumference guidelines, Adults

Not at riskIncreased riskSubstantially increased risk
MalesLess than 94 cm94 cm or more102 cm or more
FemalesLess than 80 cm80 cm or more88 cm or more

Self-perception questions

Respondents were asked whether they considered themselves to be:
    • Acceptable weight
    • Underweight
    • Overweight.

This question was not asked where:
    • A female had previously identified themselves as currently pregnant (or raised it at this point).
    • A proxy was being used for a respondent aged 15-17 years
    • A proxy was being used for an adult interview and the respondent was not present.

Data items

The questionnaire, data items and related output categories for this topic are available in pdf/Excel spreadsheet format from the Downloads page of this product.


Points to be considered when interpreting data for this topic include the following.
    • BMI was calculated for persons for whom height and weight were measured or imputed (for further information see Imputation). For 2014-15, 71.8% of respondents aged 2 years and over had their height and weight measured (i.e. This comprises 61.3% of children aged 2-17 who had their height and weight measured, and 74.5% of respondents 18 years and over who had their height and weight measured. However, to allow for the calculation of BMI for all fully responding persons, imputation was used to obtain values for respondents for whom physical measurements were not taken. The results presented as part of the 2014-15 NHS include both measured and imputed data. An investigation was undertaken to determine whether the characteristics of the people who were measured differed from those who were not measured. This investigation looked at variables such as smoking status, self-assessed health, employment status, marital status, country of birth, self perceived body mass, level of exercise and whether or not has high cholesterol (as a long-term health condition) and found no differences. While there were some differences in age, sex and part of state, these were taken account of in the weighting process. For more detail on response rates see Response rates.
    • Non-response rates for physical measurements were higher in 2014-15 than in 2011-12; for example, the non-response for BMI for adults in 2014-15 was 26.8% compared with 16.5% in 2011-12.
    • While BMI is a useful tool to assess and monitor changes in body mass at the population level, it may be an inappropriate measure of the body fatness of certain populations and certain individuals; for example, those whose high body mass is due to muscle rather than fat, those with osteoporosis who have lower than usual BMI, or those of non-European background, whose risk levels are not accurately reflected in the BMI cut-off points used. BMI can, however, be used in conjunction with waist circumference which provides a second indicator for people at risk.
    • Respondents were not specifically asked whether they were pregnant, however they were able to volunteer this during the interview. If the respondent volunteered that they were currently pregnant, the interviewer was instructed not to take their measurements and to explain to the respondent that the measurements during the course of a pregnancy will not accurately reflect their general (i.e. non-pregnant) measures.
    • If physical measurements were taken prior to being informed that the respondent was pregnant, interviewers were instructed to include a comment in the instrument confirming that the measurements taken were of a pregnant respondent, their results were excluded.
Comparability with 2011-12

In 2011-12, physical measures data was collected in both the NHS and the NNPAS surveys (i.e. the AHS Core). Data collected on measured height, weight and waist circumference in the 2014-15 NHS used the same methodology as the 2011-13 AHS and is considered directly comparable.

When making comparisons between 2014-15 and 2011-12 data it is recommended that:
As discussed in the Imputation results for all physical measurement data including BMI from 2014-15 are of suitable quality and are directly comparable to 2011-12. Differences in the equipment used for measurements are not expected to impact comparability. However, the following should be noted:
    • 'Self-assessed body mass compared to 12 months ago' was not collected in the 2014-15 NHS, but was in the 2011-12 NHS.
    • In the 2014-15 NHS, where provided, self reported data for height, weight or waist measurements has been included on the output file, along with self report flags to identify this data.