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Population Statistics

Answer

The information requested falls within the responsibility of the National Statistician who has been asked to reply.Letter from Karen Dunnell, dated 27 February 2006:"As National Statistician, I have been asked to reply to your recent Parliamentary Question asking what assessment has been made of the accuracy of the most recent population figures provided by the Office for National Statistics for Aberavon and Neath Port Talbot. (53612)""Population estimates are calculated using an internationally respected methodology. Further information can be found in the detailed methodology guide Making a population estimate in England and Wales””. This is published here: http://www.statistics.gov.uk/StatBase/Product. asp?vlnk=575""It is becoming increasingly difficult to estimate the size of the population because of changes in society, which include increased mobility and different living arrangements. The decennial Census provides a benchmark against which national and sub-national population estimates can be assessed. Substantial work has been done on the difference between mid-year population estimates and the 2001 Census. This work is summarised in the final report of the 2004 Local Authority Population Studies, which can be found here: http://www.statistics.gov.uk/downloads/theme_population/LAStudy_FullReport.pdf""These studies confirmed that the 2001 Census had worked well in most areas, including Aberavon and Neath Port Talbot, but there were a few cases where the adjustment for under-enumeration was not able to adjust sufficiently for exceptional circumstances. This work, together with revised international migration estimates, accounted for a large proportion of the initial 1.1 million difference between mid year estimates and the Census; reducing the difference to a little over 0.2 million""In addition, extensive annual quality assurance is undertaken in order to ensure the accuracy of the annual mid-year estimates. Quality assurance starts with detailed checking of the source data used in the components of change (birth, deaths, etc.). Procedures are then in place to ensure that these data sources are correctly processed when deriving the estimates. The calculated national and sub-national estimates, for all 376 local authorities in England and Wales, are then subject to a further set of quality assurance procedures before they are published. These procedures include reviews of sex ratios and age profiles, comparisons of change over time, and comparisons of fertility and mortality rates. Substantial effort has already been undertaken, in recent years, to improve the quality assurance of population estimates.""ONS is also now investing substantially in a project to Improve Migration and Population Statistics (IMPS). (More information on this project can be found at: www.statistics.gov.uk/IMPS). The key aims of this project are to reduce the size of the difference between the 2011 Census results and the mid-year estimates and to better understand any difference that does remain. As part of this project, we are developing a data comparator tool to enable us to compare the annual mid-year estimates against a range of administrative sources. This work is ongoing and the results will inform our understanding of the accuracy of the mid-year population estimates. The tool was trialled in the mid-2004 population estimates, which were published in August 2005.""Another strand of the IMPS project is a review of the quality assurance procedures that are currently in place for population estimates. One of the aims of this review is to assess what improvements can be made to existing procedures, and determine whether additional quality assurance is required.""ONS also produces population projections for each local authority area. The methodology used in the production of the subnational population projections is an established and recognised methodology. Subnational population projections undergo extensive quality assurance before publication. In addition, local authorities and health authorities are consulted on the first year of migration assumptions used as the baseline trend for migration.""Population estimates and projections are supplied to the ODPM. I understand that ODPM make checks to ensure that the data as provided by the ONS have been correctly entered into their calculations for allocating Formula Grant to local authorities. Otherwise, they do not make any assessment of accuracy of the data supplied, as this responsibility lies with the ONS."

Secondary information

Type

Written question

Reference

443 c345-6W;443 c345-6W; 53612

Session

2005-06

Subjects

Census Population Aberavon Neath Port Talbot

Link

View this Written question on www.publications.parliament.uk