Organisations such as the United Nations recommend that information on age may be secured either by obtaining the date of birth (day, month, year) or by asking directly for a persons age at their last birthday. The first method yields more precise information and, in the interests of data comparability and integration, is the recommended standard which should be used whenever possible.
Although a direct question on age is likely to yield less accurate results, there may be certain circumstances where it will be necessary or appropriate to ask a direct question on age. Asking age information by proxy is a good example where the person supplying the information is more likely to know the respondent’s age than their date of birth.
The recommended questionnaire module must obtain the date of birth: Day–Month–Year.
The questionnaire module below is an example that meets the requirements documented in this statistical standard. Other questionnaire modules may vary in format but should conform to the requirements contained in this statistical standard.