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Age categories organise the results of statistical population surveys. While apparently neutral, the thresholds used to define the categories, like the groupings made, determine the way in which major social issues are considered. Furthermore, choices with respect to age group definition in descriptive statistics may highlight or conceal particular issues. On the basis of analysis already conducted on the HID survey, we consider here first studies specifically focusing on this issue. We then expand our focus to other data sets in order to question the relevance of age groups to analyse surveys on chronic health problems. Hitherto, little work has been done in these areas. The commonest threshod is 60, which is the focus for current debates about retirement, the definition of old age and the ways in which disability is addressed. We consider the questions raised by this threshold. We also look at the age groups used in health studies in order to assess their relevance for presentation of results from the HID survey.