Data collection and publication - age: guidance

Guidance for public bodies on the collection of data on age.

Additional guidance for interviewers

Instructions and 'prefer not to say'

Instructions should be given at the beginning of the interview/survey saying why all of the questions are being asked, that they are all voluntary and, if a respondent does not wish to answer any of the questions, they do not have to. This ensures all questions are treated the same.

Testing by the ONS has shown that provision of a 'prefer not to say' option results in an increase in non-responses in telephone/face-to-face interviews. As such the recommendation is that this should only be included in online and paper surveys where refusal is not otherwise possible with the caveat that this may increase the rate of non-response to this question.

If a 'prefer not to say' option is added to this question then it should be added to all questions. In interviewer-led surveys clear instruction at the beginning should advise people that they do not have to answer any question that they do not wish to.

Proxy responses

The question should be addressed directly to the respondent. Where the respondent is unable to provide an answer, for example they are unable to use a computer, then another member of the household can be asked to give a response on their behalf.

In this case the question should be asked as the following:

Question: What was their age last birthday?


1: Refusal (spontaneous only)

2. Prefer not to say (non-interviewer led questionnaires only)

Or, if using the alternative question:

Question: What is their date of birth?


1: Refusal (spontaneous only)

2. Prefer not to say (non-interviewer led questionnaires only)

This should only be allowed as a last resort and the interviewer should record that a proxy response was given. It is very important the interviewers do not attempt to provide an answer on behalf of the respondent.



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