The new statistics published in this release are mid-2002 to mid-2010 population estimates for England and Wales revised following the 2011 Census. The mid-2011 estimates for England and Wales, based on the 2011 Census, were published on 25 September 2012.
This bulletin describes the newly consistent time-series of population estimates to mid-2011. The bulletin provides information on the size and age/sex structure of the population and describes the changes to the previously published series of estimates as a result of the revisions. A revised series of estimates at local authority level are planned for publication in Spring 2013.
The new statistics published in this release are mid-2002 to mid-2010 population estimates for England and Wales revised following the 2011 Census. The mid-year estimates refer to the population on 30 June of the reference year. The mid-2011 estimates, based on the 2011 Census, were published on 25 September 2012 and provided a base for revisions to the estimates for mid-2002 to mid-2010.
The revised estimates take into account the additional information that the 2011 Census has provided about how the population of England and Wales has changed during the decade. These revised estimates for mid-2002 to mid-2010 complete the consistent time-series of annual estimates for England and Wales to mid-2011. The estimates form the official series of population estimates and are certified as National Statistics by the UK Statistics Authority.
This bulletin describes the newly consistent time-series of population estimates to mid-2011 for England and Wales, focusing on the revised time-series and the contribution that each component of population change has made to the total population change on an annual basis since mid-2001. The bulletin also explains the impact of the revisions, comparing the revised series with the previous series. The age and sex structure of the revised population estimates series is also described in comparison with the previous estimates.
The revised estimates for mid-2002 to mid-2010 have been produced following the re-basing of the mid-2011 population estimates to the 2011 Census. The census collects a wide range of information about the population every ten years; it is the most complete source of information about the population and produces a high-quality population estimate to which the annual estimates are rebased each decade.
The 2011 Census identified a 464,000 shortfall in the estimates of the population of England and Wales over the decade. (See Background Note 5 for an explanation of why this difference is slightly smaller than the 476,000 Census Day difference referred to in the July 2012 paper ‘ Explaining the Difference Between the 2011 Census Estimates and the Rolled-Forward Population Estimates’ (361.9 Kb Pdf) ). The revised estimates reflect the estimated distribution of this difference across the decade and between components of population change.
Following the 2001 Census, a series of population estimates were produced on an annual basis using the 2001 Census as the base. These estimates are referred to as ‘rolled-forward’ estimates in this bulletin. The estimates were updated each year using a combination of registration, survey and administrative data, to reflect the different components of population change.
The resident population, by single year of age, was aged by one year, those born during the preceding year were added to the population and those who had died were removed. The estimates also took into account the movement of people coming to live within England and Wales and those leaving to live abroad (international migrants) as well as those moving between England, Wales, Scotland and Northern Ireland (internal migrants).
A census is the best estimate of the total population. As the population is moved forward from the census base, because of estimation in each of the components particularly those relating to international and internal migration, the estimates are subject to accumulating uncertainty until the next Census becomes available to re-base the series.
The revised mid-2002 to mid-2010 population estimates for England and Wales are based on the rolled-forward series of estimates updated to account for the 464,000 difference between the mid-2011 rolled-forward and mid-2011 Census-based estimates. A full description of the reconciliation work and the methods used to produce the revised estimates is available on the ONS website.
This release contains revised estimates for England and Wales. A fully consistent time-series of population estimates for the UK will be published when revised time-series are available for each of the UK constituent countries. A revised time-series of estimates for local authorities in England and Wales is planned for publication in Spring 2013, and a local area time series for the UK will follow when revised estimates are available for each of the constituent countries. Publication dates will be announced on the National Statistics Publication Hub in line with the Code of Practice for Official Statistics.
Population estimates for Northern Ireland are produced by Northern Ireland Statistics and Research Agency (NISRA) and for Scotland by National Records of Scotland (NRS). Further details of the timetables for population outputs are available for each country on their respective websites.
Mid-year population estimates relate to the usually resident population. They account for long-term international migrants (those people who change their country of usual residence for a period of 12 months or more) but do not account for short-term migrants (people who come to or leave the country for a period of less than 12 months).
ONS publishes statistics on short-term migrants separately; mid-2010 short term migration estimates for England and Wales were published in February 2012 and estimates of non-UK short term residents from the 2011 Census were published in September 2012.
The mid-year population estimates are essential building blocks for a wide range of National Statistics. They are used directly as a base for other secondary population statistics, such as population projections, population estimates by ethnic group and population estimates for small geographical areas.
They are used for weighting survey estimates such as the Labour Force Survey and other social surveys to ensure that they are representative of the total population, and they are used as denominators for rates or ratios, for example in demographic, health and economic indicators. They are an important input to a wide number of key economic and social statistics.
Key users include central and local government and the health sector, where they are used for planning and monitoring service delivery, resource allocation and managing the economy. Additionally, they are used by a wider range of organisations such as commercial companies (for market research), special interest groups and academia as well as being of interest to the general public.
For further information on how ONS population estimates meet user needs along with information on their fitness for purpose, please see the Quality and Methodology Information.
The population estimates for England and Wales have been revised by the 464,000 difference between the mid-2011 Census-based population estimates and the mid-2011 rolled-forward population estimates. This is the difference that has accumulated in the rolled-forward estimates since the 2001 Census provided the base.
The 464,000 difference comprises a revision of 416,000 (0.79 per cent) between mid-2002 and mid-2011 for the population of England and 48,000 (1.58 per cent) for the population of Wales. These revisions, published on 13 December 2012, complete the consistent time-series between mid-2001 and the mid-2011 Census-based population estimates which were published on 25 September 2012.
The 464,000 shortfall in the estimates of the population of England and Wales has been distributed across the decade to produce revised population estimates for mid-2002 to mid-2010. The differences between the rolled-forward mid-year estimates and the revised estimates are shown in Table 1. The size of the revision in the year to mid-2008 was the largest in the series at 82,000 (0.15 per cent of the rolled-forward estimate), while the size of the revision in the year mid-2011 was the smallest in the series at 12,000 (0.02 per cent of the rolled-forward estimate).
|Year||Revised MYE1||Rolled-forward MYE1||Size of revision||Total (cumulative) size of revision||Total (cumulative) size of revision as a % of rolled-forward estimate||Annual growth (revised MYE1)||Annual growth (revised MYE1) %|
Figure 1 illustrates the very small impact of the revisions in the context of the total population estimate for England and Wales for each year from mid-2001 to mid-2011.
The revised population estimates show that the population of England and Wales has grown every year between mid-2001 and mid-2011, with the largest growth in the year to mid-2011 when the population increased by 479,000, or 0.86 per cent. This is the largest annual percentage growth since year to mid-1962, which saw growth of 1 per cent, partly due to the ‘1960s baby boom’.
The year to mid-2011 also shows the largest absolute growth since the year to mid-1948, which saw an increase of 1.5 million people (note that the years following the Second World War had unusually high population growth). The rolled-forward series of estimates previously showed the largest annual absolute and percentage growth between mid-2001 and mid-2011 was also in the year to mid-2011, but the size of the growth was slightly smaller in the rolled-forward series (466,000, 0.84 per cent) than in the revised series.
Figure 2 puts the population growth seen in the last decade in the context of a longer time-series and illustrates that population growth in the year to mid-2011 was around the same level as in the early 1960s.
Population change at national level occurs as a result of two factors; a difference between the number of births and the number of deaths (also referred to as vital events) and a difference between the number of people migrating into a country and the number of people migrating out of a country (net migration).
Registration data for vital events are deemed accurate so their contribution to population change over the decade has not been revised. Part of the difference seen between the mid-2011 Census-based estimates and the mid-2011 rolled-forward estimates has been attributed to error in the estimates of migration throughout the decade. As a result, the contribution of net migration to population change during the decade has been revised.
A third component of population change has been introduced for the purposes of these revisions only, and is referred to as ‘other’. This component comprises population change that could either be caused by net migration or have resulted from uncertainty around the 2001 and 2011 Census-based mid-year estimates used as the start and end points for this series.
The ‘other’ component comprises population change for which it has not been possible to distinguish between these causes. Changes in the size of the armed forces population have also been included in this component.
Figure 3 shows the relative contributions of vital events and migration to the population growth seen in England and Wales since mid-2001. The contribution of migration in the rolled-forward series is also shown to illustrate the impact of the revisions. Figure 3 demonstrates the contribution that the different types of change have on population growth; that is, the contribution that vital events make compared to migration.
It should be noted though that the two figures are inter-linked, as past immigrants contribute to the number of births and deaths in subsequent years. It is also important to note that the estimates of population change due to migration carry greater uncertainty than the estimates of change due to births and deaths. This is because migration is estimated using survey data whilst the number of vital events is obtained from administrative registers. The contribution of migration in the rolled-forward series is also shown in Figure 3 to illustrate the impact of the revisions.
In the year to mid-2011 the relative contributions of births minus deaths (239,000) and net migration (235,000) are broadly equal. Prior to mid-2008 migration contributed to a larger proportion of the population change in each year than the difference between births and deaths. Between mid-2008 and mid-2009 however, the difference between births and deaths had a larger impact on population change than net migration.
The impact of the revisions can be seen in Figure 3 by comparing the relative contributions of net migration to the revised and rolled-forward estimates. Specifically, the larger contribution of migration throughout the decade which is concentrated between mid-2005 and mid-2009 in the revised estimates. In this period the revised estimates include additional migrants from the eight countries that joined the European Union in 2004 who were missed in the rolled-forward estimates (full details can be found in the Methods paper).
The increased level of net migration during this period has resulted in migration maintaining a larger relative contribution to population change for more of the decade than in the rolled-forward series. After mid-2009 the difference between the revised and unrevised estimates of net migration is smaller. This reflects the improvements made to the rolled-forward series arising from the Migration Statistics Improvements Programme (See ‘Past and future improvements to migration and population statistics’ section of this bulletin).
The contribution of the ‘other’ component is both small and fairly consistent across the decade. Change due to ‘other’ has deliberately been distributed evenly across the decade as it cannot be attributed to a specific component.
The larger number of births than deaths has contributed to population growth throughout the decade. Apart from the small decrease in the year to mid-2009, the number of births has increased each year since mid-2002, and the number of deaths has decreased every year. There were 136,000 more births, and 42,000 fewer deaths in the year to mid-2011 than in the year to mid-2002.
The 464,000 revision for England and Wales as a whole comprises a revision of 416,500 (0.79 per cent) between mid-2002 and mid-2011 for the population of England and 48,000 (1.58 per cent) for the population of Wales. Population growth rates between mid-2001 and mid-2011 were smaller for Wales than for England. While the largest annual growth between mid-2002 and mid-2011 for England was 0.88 per cent (465,000) in the year to mid-2011, the largest for Wales was 0.69 per cent (21,000) in the year to mid-2007.
The relative contribution of vital events and migration to population change in England and in Wales is different. While the patterns described for England and Wales mirror those for England alone, for Wales net migration has had a larger impact on population change than the difference between births and deaths until mid-2009. In mid-2010 and mid-2011 the impact of vital events was larger than the impact of migration in Wales.
The age and sex structure of the revised estimates is broadly similar to the rolled-forward estimates over the decade. However, there are some differences which are described below.
Figure 4 illustrates the age and sex structure of the England and Wales population in mid-2011. The shaded bars represent the revised mid-2011 estimates based on the 2011 Census. The structure of the pyramid is determined by patterns of births, deaths and migration.
The black outline represents the age and sex structure of the rolled-forward mid-2011 population estimates which when compared to the shaded bars, illustrates the effect of the revisions on the age and sex structure of the population of England and Wales.
Key points of interest include:
The number of males in their early to mid-twenties were overestimated in the rolled-forward estimates, so the revised estimates show fewer males at these ages.
The number of females in their late twenties and early thirties were underestimated in the rolled-forward estimates, so more females have been added into these ages in the revised estimates. This is also the case for males to a lesser extent.
There were fewer males and females aged 10-19 in the rolled-forward estimates, so the revised estimates for these ages are accordingly larger.
Both males and females aged 80 and over were overestimated in the rolled-forward estimates, so the revised estimates show fewer people in these ages.
Those aged 64 show a marked difference between the revised and rolled-forward estimates.
The differences between the revised and rolled-forward estimates by age and sex begin to show from around mid-2007. Prior to mid-2007, the differences are particularly small and no one five-year age/sex group has been revised by more than 3 per cent of the rolled-forward population estimate in this period. The larger differences are visible from mid-2007 and persist to mid-2011 to appear in the differences highlighted in the pyramid.
For each year between mid-2001 to mid-2011, the population comprises 49 per cent males and 51 per cent females. This was also the case in the rolled-forward estimates. Similarly, the proportion of the population aged under 16 remained around 20 per cent and the proportion of the population aged 65 and over was around 16 per cent across the decade in the revised as well as the rolled-forward estimates.
The revised population estimates for mid-2002 to mid-2010 complete the consistent time series of official population estimates. The estimates are certified as National Statistics by the UK Statistics Authority. These estimates will form the basis of the revised local authority and small area population estimates for mid-2002 to mid-2010.
Population estimates are used to calculate rates, such as fertility rates. Revisions to rates for life events will take place in the relevant future releases.
The revised England and Wales national population estimates for mid-2002 to mid-2010 will be used to inform the demographic assumptions for the 2012-based national population projections for the UK which are due to be published in October-November 2013.
ONS does not intend to revise its published Long Term International Migration (LTIM) estimates to reflect the additional migration flows that have been added to the revised mid-2002 to mid-2010 population estimates. It intends to publish a report in 2013 that will analyse the quality of LTIM since 2001, including the impacts of improvements made to the methods during this period.
Additionally, the IPS was improved in 2009 to provide better coverage of points of entry across the UK, countering limitations of the International Passenger Survey (IPS) that may have caused underestimation of certain groups of migrants in the past. Therefore any revisions to past years will not affect the quality of more recent and future estimates.
Population estimates are also used for weighting survey estimates such as the Labour Force Survey and other social surveys to ensure that they are representative of the total population. Survey estimates will be revised to reflect these revisions to the population estimates in due course where appropriate following release of revised subnational population estimates.
In March 2012, ONS completed a four year programme to improve migration and population statistics. Improvements delivered as a result of this programme, such as improvements to the International Passenger Survey (used to measure international migration) as a result of the Port Survey Review, as well as other improvements delivered outside of the programme, have been incorporated into these revisions where appropriate.
Where improvements previously only covered part of the decade, an estimate of the effect of the relevant improvements had they been applied across the whole decade has been made for the purposes of the revisions. Further details can be found in the Methods paper.
The reconciliation work carried out in order to produce these revisions will inform further improvements to population statistics for mid-2012 and beyond as well as the subnational revisions for mid-2002 to mid-2010 planned for publication in March-April 2013. ONS will also continue research to make further improvements to population statistics. Priority areas for future developments will be set following the completion of the Census reconciliation exercise taking into account consultation with users planned for Spring 2013.
These revised mid-2002 to mid-2010 population estimates complete the consistent time series of population estimates to mid-2011. Future releases of population estimates and projections in 2013 include:
Spring 2013: Revised population estimates for subnational areas in England and Wales, mid-2002 to mid-2010.
Spring 2013: Super Output Area population estimates for England and Wales, mid-2011 (2011 Census based).
June-July 2013: Mid-2011 population estimates for the UK (2011 Census based).
June-July 2013: Mid-2012 population estimates for the UK.
October-November 2013: 2012-based UK national population projections.
Some dates given here are provisional. Any changes or confirmation of dates will be announced on the UK statistics Publication Hub release calendar.
National Statistics are produced to high professional standards set out in the Code of Practice for Official Statistics. They undergo regular quality assurance reviews to ensure that they meet customer needs. They are produced free from any political interference.
An Overview of Population Statistics is available on the ONS website.
Mid-2002 to mid-2010 population estimates data for England and Wales are available on the ONS website. Published tables for mid-2002 to mid-2010 include England and Wales by single year of age and sex and broad components of population change. Unformatted tables to enable re-use of the data are also published by single year of age and sex. Mid-2001 and mid-2011 population estimates have been included in relevant the tables for this release to provide a complete and consistent time-series. Note that mid-2001 and mid-2011 have not been revised as part of this release. Mid-2001 population estimates for England and Wales were published in September 2004 and mid-2011 population estimates were published on 25 September 2012.
Population estimates for mid-2001 have not been revised. Although it is acknowledged that there is uncertainty in the 2001 Census base, the size of the discrepancy between the mid-2011 Census-based and rolled-forward estimates is not large enough to warrant a revision to population estimates for years prior to and including mid-2001. Any such revisions would cause a disproportionate burden on users.
The 464,000 difference seen between the mid-2011 Census-based and rolled-forward population estimates is slightly smaller than the 476,000 Census Day difference referred to in the July 2012 paper ‘Explaining the Difference Between the 2011 Census Estimates and the Rolled-Forward Population Estimates’. This is because that comparison already included corrections applied to asylum seeker and visitor switcher estimates for mid-2009. Full details are available in the Methods document that accompanies this release.
2011 Census results for England and Wales are available on the ONS website.
The 2011 Census in Scotland is run by National Records of Scotland (NRS); the first release of data is scheduled for publication on 17 December 2012. Population estimates for Scotland are also produced by NRS.
2011 Census results for Northern Ireland are produced by the Northern Ireland Statistics and Research Agency (NISRA) and are available on their website. Population estimates for Northern Ireland are also produced by NISRA.
A methods guide describing the methodology used to revise the mid-2002 to mid-2010 population estimates following the 2011 census is available.
Net migration estimates in this report include net international migration, net flows of asylum seekers, and the net effect of cross-border moves between England and Wales and the remainder of the UK.
Further information on the quality of mid-year population estimates can be found in the Quality and Methodology Information (QMI).
Information on those people that have pre-release access can be found on the ONS website.
Details of the policy governing the release of new data are available from the Media Relations Office. Also available is a list of the names of those given pre-publication access to the contents of this release.
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