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Age (AGEP)

Census of Population and Housing: Census dictionary
Reference period
2021

Definition

This variable collects each person's age. If age is not reported, it is imputed. See Imputation flag for age (IFAGEP). For infants aged less than one year, 0 years of age is recorded.

Data is also available in 5 year groups (AGE5P) and 10 year groups (AGE10P).

Scope

All persons

Categories

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CodeCategory

000-115

0 to 115 years of age singly

Number of categories: 116

Question(s) from the Census form

What is the person’s date of birth and age?

What is the person’s date of birth and age?
What is Person 1's date of birth?

If date of birth is not known, please select 'Don't know date of birth' and provide Person 1's age.

More information

Day Month Year

OR

Don't know date of birth

Age
Age example
What is Person 1's date of birth?

If date of birth is not known, please select 'Don't know date of birth' and provide Person 1's age.

More information

Day Month Year

OR

Don't know date of birth (selected response)

Age years

Example

Age example

Example

What is Person 1's date of birth?

If date of birth is not known, please select 'Don't know date of birth' and provide Person 1's age.

More information

Day Month Year
18 March 1993

OR

Don't know date of birth

Age
28 years

More Information

Additional information relating to the question on: What is the person’s date of birth and age?

More Information

What is Person 1's date of birth?

If date of birth is not known, please select 'Don't know date of birth' and provide Person 1's age.

More information

It is important to note:
• Date of birth is the date that the person was born.
• Age is required only if the person's date of birth is not known. Please report age at Census night – Tuesday 10 August 2021.

If the person is less than one year old and their date of birth is not known, enter '0' in the age box.

How this variable is created

Age is calculated from date of birth when provided, otherwise stated age is used. Where both sets of information are provided, date of birth is used to derive an age in years, except in circumstances where errors in the date of birth are identified. Age data is only output in whole years.

If neither age nor date of birth is provided, age is imputed. Imputation is a statistical process for predicting values where no response was provided to a question and a response could not be derived. There are two scenarios where this occurs:

  • when no Census form is returned
  • when a respondent does not answer the age question

Where no Census form has been returned for a dwelling that is identified by a Census Field Officer as having been occupied on Census night, people are imputed into that dwelling (both numbers and key demographic characteristics such as age, sex, marital status and usual address). Most imputed ages are attributed to imputed people.

Where a respondent does not answer the age question, age is imputed using other information on the form and using an age distribution of the population. The variable Imputation flag for age (IFAGEP) is used to indicate if a person's age has been imputed for the Census.

Where respondents report an age outside the acceptable range or where there were inconsistencies between age and relationship data, age is also imputed.

History and changes

A question relating to age has been asked in every Census since 1911. Since 2006, respondents have had the option to report either date of birth or age in years.

For 2021, question wording changed from 'or' to 'and' in both the question wording and response area. The online form has been changed to primarily ask for date of birth (DOB) and the respondent is presented with a check box if DOB is not known so that they can enter the person’s age. This is to encourage the provision of more accurate data.

Data use considerations

Age data, combined with sex data, is essential to produce accurate population estimates based on the Census count.

Age is used during processing as a cross check with other variables; for example, the age of the respondent determines whether particular questions asked in the Census are applicable.

Related variables and glossary terms

Other ABS sources