The Office for National Statistics have been hard at work revising their methodology for creating population estimates. Revised mid-year estimates for local authority resident populations were published in summer, with revised small area estimates published earlier this month. This includes the 2009 population estimates, as well as revised estimates for 2002-2008.
The overall national population has not been changed, only the way that this is split between local authorities and small areas. Elsewhere we’ve published analysis onthe changes at local authority level (published on our OCSI blog).
- 50 local authorities see a 2% or greater shift in 2008 population estimates (with some age-gender groups changing significantly more). The largest estimate increases tend to be seen in metropolitan areas, including a number of inner and outer London boroughs and larger cities. The largest decreases tend to be seen in more rural areas, including parts of East Anglia and the rural East Midlands.
- At neighbourhood level, the population revisions can affect the estimated populations of small areas very significantly. For example, one Super Output Area (LSOA) in Yorkshire shows an 88% increase in population using the revised estimates, while another Yorkshire LSOA shows a 41% decrease in estimated populations.
- As 2009 estimates are published using the new methodology, any consistent time series will need to use the revised 2002-2008 data, rather than continuing to use the older unrevised data (which will not be consistent with the 2009 data). This will affect all indicator rates that are calculated using population numbers from the 2002-2008 population estimates, for example unemployment and incapacity benefit rates.
- Data suppliers will likely produce revised data over time to take into account these changes where appropriate, for example there may be some revisions to national indicators.
Given the impact on critical local indicators such as unemployment benefit rates, local information systems need to be using the updated data. We have already revised all indicators in the Data Packs to reflect the new population denominators, and will revise indicators from other suppliers as and when these are published. Users of the Data Packs again benefit from time and resource savings.
The full list of new and updated datasets are in the User area (login required), including details of all indicators in the Data Packs.