Area Level Index of Age Diversity in the UK, 2002-2019

The Area Level Index of Age Diversity (ALIAD) is based on the Simpson's Index of Diversity. It is commonly used in ecological studies to quantify the biodiversity of a habitat as it takes into account both the richness, i.e. the number of species present, and the evenness, i.e. the abundance of each species, within an environment. As species richness and evenness increase, so diversity increases. The index represents the probability that two randomly selected individuals will belong to different groups. It ranges from 0 and 100, with higher values representing greater diversity.
ALIAD was computed for each Lower Super Output Area (LSOA) in England and Wales (E&W), each Data Zone (DZ) in Scotland and each Super Output Area (SOA) in Northern Ireland from 2002 to 2019. It is based on the mid-year population estimates (MYPE) for each area for each year. This is information is freely available in accordance with version 3.0 of the Open Government Licence. However, the different national statistical agencies compute MYPE for different age groups. In England and Wales estimates are provided for single-year age groups, i.e. the number of people aged 0, 1, 2, 3, etc. In Scotland estimates are provided for quinary age groups, i.e. the number of people aged 0-4, 5-9, 10-14, etc. In Northern Ireland (NI) estimates are provided for four larger age groups, i.e. 0-15, 16-39, 40-64 and 65+. It was decided to match the age groups to the NI classification as i) this would provide the greatest geographical coverage, ii) the estimates ought to be more robust and iii) in discussions with policy and practice stakeholders these age groups were seen as more meaningful than single-year or quinary age groups. An exact match was possible between the E&W and NI age groups. However, because of the use of quinary age groups it is not possible to get an exact match for all age groups in Scotland. Hence, the age groups used on Scotland are 0-14, 15-39, 40-64 and 65+.
The final dataset contains the computed ALIAD values for each of the 34,753 LSOAs, the 6,976 DZs and the 890 SOAs from 2002-2019. ALIAD has a range of 0-100. On this scale 0 would represent total age concentration, i.e. every member of the area is in the same age group, and 100 would represent complete age diversity within the area.