The standard output categories are aggregations of the input categories (the level at which age data are collected and stored).
The ABS recommends five or ten year age groups for most applications with cut off years varying according to the type of survey, or user requirements.
The recommended guidelines for developing output classifications for age are as follows:
- The recommended standard output classification should consist of five year groupings.
- Groupings with a range of more than five years should be in multiples of five years. It is important to ensure as many categories as possible are multiples of five years, or capable of aggregation to such groupings, to facilitate maximum comparability of age data from different sources.
- Groupings with a range of less than five years, including single years, should be capable of aggregation to five year groupings as subtotals.
- Subtotals of groupings, and groupings with a range of five years or more, should start at numbers ending with the digits '0' or '5' and finish in numbers ending with the digits '4' or '9'; for example, 15-19 and 20-24.
- The first group in any set of groupings should have a dash between two numbers (e.g. 0-4), not 'under' (e.g. under 5). Labels such as '4 years and under' are only acceptable under special conditions for example, data included in the first category do not necessarily span the full range of the standard category.
- The last group in any set of groupings should have the first number of the last age range followed by the words 'and over' (e.g. 75 and over), not the first number of the range followed by a '+' (e.g. 75+).
Certain circumstances may require output categories to vary from the recommended five and ten year groupings. For example, it may not be suitable for statistical data relating specifically to children or the elderly to use standard five and ten year groupings.
When developing output classifications or presenting age data, it is recommended to adhere to as many of the above guidelines as possible. However, it is not essential to adhere to these guidelines, if there are compelling reasons (e.g statistical) for deviating.
Guidelines for reporting 'Age' data in published tables are as follows:
- It is recommended, but not always appropriate for all totals in tables be labelled 'Total'. An exception is in life tables, as they show the calculated longevity of populations at particular ages, rather than counts or estimates.
- If 'Age' is used in the table stub, the stub heading should be labelled 'Age group' followed in brackets by the unit of time used. The following labels are recommended:
- 'Age group (years)'
- 'Age group (months)'
- 'Age group (weeks)'
- 'Age group (days)'.
- Units of time (e.g years, months, weeks, days) should not be mixed in table stubs unless a specific data collection requires it. For example, data relating to infant deaths may require a combination of time units such as minutes, hours, days or weeks.
- It is not acceptable to use a single category labelled '0' for infants under one year, as days, weeks or months rather than years are the appropriate time units for measuring the age of infants. If a single category is used, it should be labelled 'Under 1 year'.
- When survey scope restricts age ranges, output age groups should start at the beginning of the age range and finish at the end of the age range. For example, in a survey where the scope is persons 15-64 years the first age group should begin at 15 years and the last age group should end at 64 years and collections may need to use some age groups of less than five years. The first age grouping for a collection with a minimum age limit of two years should be '2-4 years', followed by standard five year age groups such as '5-9 years', '10-14 years' etc.
- The use of an open ended age group at the top of the age range is acceptable when presenting 'Age' output (e.g. '75 and over', '85 and over', etc.) provided there is an adequate sample size to support the group.
- Data from sources which have a 'Not stated' code for 'Age' may include a 'Not stated' category in the table. Alternatively, the 'Not stated' response may be incorporated into totals, providing that the 'Total' is footnoted to show it includes these responses.
The age categories below are the recommended output categories, however flexibility with groupings is allowable depending on purpose, scope or source of data.