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Baby boom

Baby booms are short-term increases in birth rates, and have been recorded following the two World Wars and during the late 1950s to early 1960s. The children born during these events are often termed ‘baby boomers’ and the impact on population figures when the baby boomers themselves have children has been termed the ‘Echo Effect’.

Age-specific fertility rates

The Age Specific Fertility Rate (ASFR) is the number of live births per 1,000 women of a specific age in a specified period. For example, the age-specific fertility rate for 25-29 year old women in 2010 is calculated by dividing the number of births in 2010 to women aged 25-29 by the estimated population of women of that age in that year.


Age is derived from the date of birth question and is a person's age at their last birthday. Dates of birth that imply an age over 115 are treated as invalid and the person’s age is imputed. Infants less than one year old are classified as 0 years of age.

Adult lifestage

Adult lifestage classifies adults in households aged 16 to 24 by the presence of dependent children in the household. Adults aged between 25 and 54 are classified by age, by the presence of dependent children in the household, and by the age of the youngest dependent child if any are present. Adults aged 55 and over are classified by age and whether they are in one- or two-person households. Those aged 55-74 are further classified by the presence of dependent children.

Adult (alternative classification)

In a small number of census results, for example some versions of 'Household composition' or 'Adult lifestage', adult is used to refer to those aged 16 and over and children to those aged 15 and under. This definition is different from the standard definition for adults, children and dependent children used in most census results. When this definition is used, it is clearly indicated.


An adult in a household is defined as any person who is not a dependent child. This definition is used in most results from the 2011 Census. In results where a different definition is used it is clearly indicated.

Accessibility standards

As part of its Web Accessibility Initiative (WAI), the World Wide Web Consortium (W3C) published a set of Web Content Accessibility Guidelines (WCAG), along with a checklist for evaluating website compliance and this has become the accepted international standard.  This web site has been designed to comply with web accessibility standards including XHTML v1.0, CSS 2.0. and WAI Priority 2.


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