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Frequently Asked Questions: Annual Population Estimates (UK), June 2014

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Contact information

Population Estimates Unit:


Telephone: 01329 444661

Address:Office for National Statistics
Population Estimates Unit
Segensworth Road
PO15 5RR

Methodology and Quality information on UK population estimates

The United Kingdom Annual Population Estimates Frequently Asked Questions.

Which are the latest available population estimates?

The estimates released today are for the year ending June 30 2013. These are comprehensive estimates of the population of the United Kingdom (UK) that are consistent with the results of the censuses conducted across the UK in 2011. 

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Which population estimates are available?

  • Annual UK population estimates at mid-2013: These estimates provide the most recent population figures for the UK.  Population estimates are provided by sex and single year of age.

  • UK components of population change estimated for the year ending mid-2013: These estimates provide a breakdown of the causes of the UK population change for the year between 1 July 2012 and 30 June 2013.  Estimates of births, deaths, internal migration (inflow, outflow, net), international migration (immigration, emigration, net), and other changes are given.

All data relates to the usually resident population at the reference date of 30 June 2013.

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Which geographies do the estimates cover?

Estimates are presented for a range of UK geographies and local government areas:

  • United Kingdom; 

  • Great Britain; 

  • England; Scotland; Wales; and Northern Ireland;

  • Regions, counties, unitary authorities and county districts in England;

  • Council areas in Scotland; 

  • Unitary authorities in Wales; and

  • District council areas in Northern Ireland.

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Who produces the UK population estimates?

The Office for National Statistics (ONS) compile and publish population estimates for the UK using estimates for England and Wales (also produced by ONS), estimates for Scotland produced by National Records of Scotland (NRS) and estimates for Northern Ireland produced by the Northern Ireland Statistics & Research Agency (NISRA).

Population estimates for each of the UK constituent countries are compiled using a common methodological approach and aim to be as consistent as possible; however there are some differences in the detail of the data sources and methods used.

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Can I have more detailed estimates than those included in the standard tables on the website?

The most detailed estimates available are now published as standard. Whilst the main published data tables show estimates rounded to the nearest hundred we are encouraging re-use and analysis of the estimates by also publishing an unformatted dataset showing unrounded estimates at local level by single year of age and sex.

Users should note that unrounded data cannot be guaranteed to be as exact as the level of detail implied by unit level data. We advise that data should be rounded to the nearest hundred if quoted in any publication.

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What information has been released to support users and where can I find it?

The Statistical Bulletin presents the key messages on the size and age structure of the population shown by the mid-2013 UK population estimates and the changes that happened since mid-2012.

The standard data tables for the mid-2013 UK population estimates are available by all geography levels local authority and above, single year of age and sex. A summary table MYE1 is provided that presents the population estimates by quinary age groups for each country, Great Britain and the UK:

  • MYE1: Summary table of population estimates by country and quinary age, including subtotals for males and females and grand total;

  • MYE2: Detailed population estimates for all geography levels, local authority and above, by sex and single year of age 0-90+;

  • MYE3: Components of population change estimates for all geography levels, local authority and above.

A population estimates analysis tool (10.42 Mb ZIP) is available for users to produce simple reports on the latest mid-2013 UK population data.  The tool includes a population pyramid able to be viewed by country, region, county or local area.

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Can I have more detailed estimates than those included in the standard tables on the website?

The most detailed population estimates available are now published as standard. More detailed components of population change are available for England and Wales by sex and single year of age for regions, counties, unitary authorities and county districts in England; and unitary authorities in Wales in the population estimates analysis tool (10.42 Mb ZIP) .

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Are specific individuals able to be identified in the detailed estimates?

No. The UK population estimates made available are protected against disclosure of individuals' information.  Estimates of births and deaths are consistent with those published elsewhere by ONS, NRS and NISRA. Other population component estimates are the result of applying statistical models to administrative and survey data and are not exact counts.

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Are mid-2013 UK population estimates available for certain age groups such as pensioners or school aged children?

Population estimates by single year of age are available for users to calculate preferred age groups. These estimates can be found in the unformatted dataset included with the standard data tables (9.62 Mb ZIP) .

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What about the population estimates at the oldest ages, are they included?

Estimates of older people (those aged 90 and over) are included in the mid-2013 UK population as a total figure; estimates by single year of age are presently not shown.  More detailed estimates by single year of age are available in the Estimates of the Very Old (including Centenarians) for the United Kingdom release covering mid-2002 to mid-2012.

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Are mid-2013 UK population estimates available for health areas?

No.  The UK mid-2013 subnational population estimates are produced for local government administrative boundaries only.  Estimates for health areas (NHS Boards in Scotland, Local Health Boards in Wales, and Health & Social Care Trusts in Northern Ireland) are available from the relevant provider: ONS, NRS or NISRA

Estimates for the old Strategic Health Authorities in England can be derived by aggregating local authority estimates as appropriate, and advice on how to do this can be provided by the Population Estimates Unit at ONS.  Population estimates for Clinical Commissioning Groups in England effective from April 2013 are available as part of the set of Small Area Population Estimates produced by ONS

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Is there a consistent set of UK population estimates from 2001-2011 now available?

Yes.  Revised Annual Mid-year Population Estimates, 2001 to 2010 for the UK, consistent with the 2011 censuses was published in December 2013.  Annual Mid-year Population Estimates, 2011 and 2012 for the UK was published in August 2013.

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What are the key findings from the population estimates, for the year ending 30 June 2013?

The latest population estimates show: 

  • The population of the UK stood at 64,105,700 in mid-2013, up from 63,705,000 in mid-2012.  This represents a growth of 400,600 (0.63%) in the year to 30 June 2013. 

  • The populations of the four constituent countries of the UK in mid-2013 are:

    o England: 53,865,800;
    o Scotland: 5,327,700;
    o  Wales: 3,082,400; and
    o Northern Ireland: 1,829,700.

  • There were 792,400 births and 580,300 deaths occurring in the year to 30 June 2013.  This is the highest number of deaths seen since the year to mid-2005.  

  • The flow of international migrants to the UK in the year to 30 June 2013 was 503,700 and outflow for the same period was 320,400.  This means that UK net migration was 183,400 in the year to mid-2013. 

  • The population increase of  the UK in the year to 30 June 2013 was caused by there being 212,100 more births than deaths (53% of the increase) and 183,400 more international migrants arriving than emigrants leaving (46% of the increase). 

  • The mid-2013 population of the UK ranks third, behind Germany and France when compared to other member states of the European Union.

Further information on these key messages can be found in the accompanying Statistical Bulletin.

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How are the 2013 UK population estimates produced?

Every ten years the mid-year population estimates are rebased on the results of each constituent country’s census. The mid-2011 UK population estimates are based on the results of the three censuses performed: for England and Wales, for Scotland, and for Northern Ireland.  The mid-2013 UK population estimates have been compiled based the mid-2012 population estimates that were first published by ONS on the 8 August 2013.

In a non-census year such as 2013, the population estimates for the previous mid-year are rolled forward by a year using the cohort component method:  the resident population for the previous mid-year is aged by one year, those born during the previous year are added on to the population and those who have died during the previous year are removed.

Estimates of international migration movements of people into and out of the UK and internal migration movements within the UK are applied to the estimated population. The population subgroups for prisoners and armed forces (UK forces and foreign) are estimated separately from the rest of the population as they are not covered by the migration data sources used.

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Where can I find out about how UK population estimates are produced?

An Information Note is available that outlines the similarities and differences of how population estimates across the UK are produced and explains the impact for users of the statistics.

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Why don’t we make more use of administrative data sources in the compilation of the UK population estimates

Administrative data is used in the production of UK population estimates, for example data on GP patient registrations are used within the cohort component method to estimate internal migration. Data from the civil registration systems of births and deaths are similarly used, as are aggregated data from the Ministry of Defence on forces personnel.

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Why don’t the mid-year estimates include short-term migrants?

Mid-year population estimates refer to the usually resident population of an area. Usual residence is the standard United Nations definition for population estimates and includes people who reside in the area for a period of at least 12 months. Only long-term international migrants (people who enter or leave the UK for a period of at least one year) are accounted for in the estimates.

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Are the population estimates consistent with those produced in other population statistics eg small area population estimates?

Yes. The mid-year population estimates are used for calculating other official population statistics such as small area population estimates, estimates of the population by marital status and estimates of the elderly population. These outputs have been rebased and revised to reflect the censuses carried out in 2011 and are consistent with the mid-year population estimates.

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Are the population estimation methods robust?

Population estimates are produced using a well established demographic approach called the cohort component method. This involves combining information from a number of data sources including the 2011 censuses, survey data and administrative registers. The data sources used are the best that are available on a nationally consistent basis down to local level, however the estimates are subject to the coverage and error associated with these sources.

Information from administrative registers such as the numbers of births and deaths is considered to be very reliable. However, estimates of international migration are obtained from the International Passenger Survey (IPS) and are therefore subject to sampling and other types of error. Whilst national IPS figures have relatively small levels of uncertainty, at local levels the sample counts in the IPS are small and it is necessary to combine data across years and distribute figures using other data sources. At this level, individual migration estimates are subject to greater levels of uncertainty.  However the impact of uncertainty associated with net migration flows is small as a percentage of the local mid-year population estimates.

Links to more detailed descriptions of the methods and quality associated with international migration estimates are available for each constituent country from the ONS, NRS and NISRA websites.

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What checks have been done to ensure the quality of the population estimates?

Extensive analysis is carried out to validate and quality assure the data and estimates at every stage of the process. When data is received for the various components, checks are carried out and comparisons made with previous years’ data to gauge consistency and completeness of coverage. The data are then processed electronically to produce the mid-year estimates. Quality assurance takes place at each stage to ensure the processing has been carried out correctly. The final estimates are analysed to ensure the new population figures are plausible.

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Do the new estimates show previous estimates being incorrect or unreliable?

No. The estimates are for 2013 only and are based on the published 2012 mid-year estimates.  Each constituent country has, in recent years, made a number of improvements to methods of estimating population change (in particular, estimating migration flows within the UK and allocating international migration flows to local areas) and the estimates would be expected to be more reliable immediately after rebasing to the Census. The ONS, NRS and NISRA are continuing a programme of research and development of data sources with the aim of improving methods further.

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Why do the population estimates show a different picture to our administrative sources at a local level?

Users often compare population estimates for individual local areas to other data sources, for example administrative records or anecdotal evidence. Comparisons between datasets should be treated with caution as there are always definitional differences in the data collected. For example, whether the data differentiate between long-term or short-term migration or whether they account for individuals who have left the area. Other data sources may also cover only a subset of the population. 

ONS has made available a 2013 Mid-year estimates QA pack that allows comparisons to be made between a range of administrative data sources and the mid-year estimates across local authorities in England and Wales.

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How good are the estimates of international migration used in the population estimates?

Estimates of Long-Term International Migration (LTIM) are:

Further information about the Quality of the IPS in relation to migration flows can be found on the ONS website.

Long-term International migration estimates are based on a small number of interviews (between 4,000 and 5,000 per year). Due to the complex methodology used to make estimates of LTIM, ONS is unable to produce confidence intervals for these estimates. However, it is possible to produce confidence intervals for the IPS component of the estimates.  The confidence intervals are relatively large where the estimates are based on a small number of contacts in the IPS. A larger confidence interval indicates greater uncertainty over the true value of the estimate. More information can be found on the Long-term International Migration Methodology Page.

To see how estimates of long term international migration measure against the code of practice dimensions of quality, please see the Quality and Methodology Information Report for International Migration.

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What about the accuracy of population estimates at the oldest ages?

There is some degree of uncertainty around all population estimates, including Census estimates, and any error in the estimates of older people will be carried forward to future years in inter-censal population estimates.

ONS produces annual 'Estimates of the Very Old' (a release of Estimates of the Very Old (including Centenarians) for the United Kingdom covering mid-2012 was published in March 2014). These are mid year estimates by sex and single year of age for persons aged 90 to 104 and for the 105 and over age-group for the UK. They are produced using the Kannisto-Thatcher (KT) method. The KT method is a version of the survivor ratio method which produces age-specific estimates of population at older ages using data from death registrations.  

The KT methodology initially produces a lower estimate of the total population aged 90 and over than the 90 and over estimate in the mid-year estimates. However in order to provide users with a consistent set of single year estimates beyond age 89, the  estimates for the current year and the recalculated back years are constrained to sum to the 90 and over totals in the annual mid year estimates for males and females separately for the current year and previous years.

There are a number of sources of possible error in the Census estimate (and hence the mid year estimates) for people at the highest ages. These include non-response and inaccuracies in reporting of dates of birth (for example proxy reporting by carers). Such inaccuracies have been documented in previous censuses.

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Why are the estimates published one year after the reference date?

The mid-year population estimates are typically published around one year after the reference date. This time lag reflects the availability of the data sources which measure the components of population change over the year preceding the estimate, and the time required to process the data and calculate the estimates.  Estimates for Scotland are usually available earlier than those for England and Wales, and Northern Ireland.

In the year following the release of census estimates, the mid-year population estimates are published later than the usual release date to allow for the processing of census results.

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What is the timetable for future publications in 2014?

This release of population estimates for the UK is the seventh ONS population estimates product to be published based on the results of the 2011 Census. Corresponding estimates for Super Output Areas, wards, Parliamentary Constituencies, Health Areas and National Parks will be released later in 2014. Publication dates for these will be confirmed on the UK statistics Publication Hub release calendar.

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