Use this code if self-reported body mass (weight) is unknown.
CODE 999 Not stated
Use this code if self-reported body mass (weight) is not responded to.
Data element attributes
Collection and usage attributes
Collection methods:
The method of data collection, e.g. face to face interview, telephone interview or self-completion questionnaire, can affect survey estimates and should be reported.
The data collection form should include a question asking the respondent what their weight is. For example, the ABS National Health Survey 1989-90 included the question 'How much do you weigh without clothes and shoes?'. The data collection form should allow for both metric (to the nearest 1 kg) and imperial (to the nearest 1 lb) units to be recorded.
If practical, it is preferable to enter the raw data into the data base before conversion of measures in imperial units to metric. However, if this is not possible, weight reported in imperial units can be converted to metric prior to data entry using a conversion factor of 0.454 kg to the lb.
Rounding to the nearest 1 kg will be required for measures converted to metric prior to data entry, and may be required for data reported in metric units to a greater level of precision than the nearest 1 kg. The following rounding conventions are desirable to reduce systematic over reporting (Armitage and Berry 1994):
nnn.x where x < 5 - round down, e.g. 72.2 kg would be rounded to 72 kg.
nnn.x where x > 5 - round up, e.g. 72.7 kg would be rounded to 73 kg.
nnn.x where x = 5 - round to the nearest even number, e.g. 72.5 kg would be rounded to 72 kg, while 73.5 kg would be rounded to 74 kg.
Comments:
This metadata item is recommended for persons aged 18 years or older. It is recommended for use in population surveys when it is not possible to measure weight.
It is recommended that in population surveys, sociodemographic data including ethnicity should be collected, as well as other risk factors including physiological status (e.g. pregnancy), physical activity, smoking and alcohol consumption. Summary statistics may need to be adjusted for these variables. Metadata items currently exist for sex, date of birth, country of birth, Indigenous status and smoking. Metadata items are being developed for physical activity.
Presentation of data:
Means and 95% confidence intervals, medians and centiles should be reported to one decimal place. Where the sample permits, population estimates should be presented by sex and 5-year age groups. Estimates based on sample surveys may need to take into account sampling weights.
For consistency with conventional practice, and for current comparability with international data sets, recommended centiles are 5, 10, 15, 25, 50, 75, 85, 90 and 95. To estimate the 5th and 95th centiles, a sample size of at least 200 is recommended for each group for which the centiles are being specified.
For some reporting purposes, it may be desirable to present weight data in categories. It is recommended that 5 kg groupings are used for this purpose. Weight data should not be rounded before categorisation. The following categories may be appropriate for describing the weights of Australian men and women, although the range will depend on the population. The World Health Organization's range for weight is 30-140 kg.
Weight < 30 kg
30 kg = Weight < 35 kg
35 kg = Weight < 40 kg
... in 5 kg categories
135 kg = Weight < 140 kg
Weight => 140 kg
On average, body mass (weight) tends to be underestimated when self-reported by respondents. Data for men and women aged 20-69 years in 1989 indicated that men underestimated by an average of 0.2 kg (sem of 0.05 kg) and women by an average of 0.4 kg (sem of 0.04 kg) (Waters 1993). The extent of underestimation varied with age.
Source and reference attributes
Origin:
National Centre for Monitoring Cardiovascular Disease
