Invitation to provide feedback on timescales for future national and subnational population projections

You are invited to provide feedback on how we may approach publication of the next national population projections (NPPs) and subnational population projections (SNPPs). We are particularly interested in your views on the questions outlined in Section 6 of this article. Instructions on how to respond by 12 November 2020 are outlined in Section 7.

On behalf of the National Statistician and Registrars General, NPPs are produced by the Office for National Statistics (ONS) for each UK constituent country and for the UK as a whole.

SNPPs, at local authority, national park and health board level, are produced by:

• the ONS for England
• National Records of Scotland (NRS) for Scotland
• Northern Ireland Statistics and Research Agency (NISRA) for Northern Ireland
• Welsh Government (WG) for Wales

After reviewing your feedback, decisions on future timescales for the NPPs will be taken by the NPP committee, which includes representatives from the ONS and the devolved administrations.

Decisions on future timescales for the SNPPs will be taken by the ONS, NRS, NISRA and the WG for each country, and will be informed by your feedback to this article as well as local consultations, which may take place in each country.

Household projections are not included in the scope of this user engagement exercise and we will update you on these separately.

This article invites feedback on how we may approach the publication and timing of the next national population projections (NPPs) and subnational population projections (SNPPs).

In the most recent 2018-based national population projections and 2018-based subnational population projections for England, the Office for National Statistics (ONS) indicated an intention not to produce 2020-based projections for publication in autumn 2021 (NPPs) and spring 2022 (SNPPs). Whilst national population projections are usually produced every two years, the rationale not to produce a 2020-based set was to allow the next set of projections to be based on 2021 Census data. In addition, 2020-based projections would have been published close to the provisional first release of 2021 Census data in 2022.

This approach was intended to enable us to use the updated base population that the 2021 Census results will offer and produce a revised back-series of earlier years of input data.

Since this intention was communicated:

• stakeholder feedback has indicated a need for 2020-based NPPs
• there is growing interest in how the projections might be impacted by the coronavirus (COVID-19) pandemic
• Scottish Government Ministers have announced that Scotland’s Census will now take place in March 2022

ONS has recently published articles on its Operational planning response to the coronavirus (COVID-19) for Census 2021, England and Wales and the Statistical design for Census 2021, England and Wales. Further information on Scotland’s Census moving to 2022 due to the impact of COVID-19 can be found in the news release.

The current timings for when data might be available from the censuses across the UK are:

Provisional first release:

• 2021 Census in England and Wales, spring 2022
• 2021 Census in Northern Ireland, summer 2022
• 2022 Census in Scotland, spring 2023

These timescales indicate approximate dates for the first release of census data. The data needed to feed into the national population projections (NPPs) may be part of later releases.

When new census data are available, the population estimates over the previous decade are subsequently revised to ensure a consistent data time series. In light of the 2021 Census results, the mid-2012 to mid-2020 population estimates will be rebased at the national and subnational level.

The methodology for rebasing the population estimates will involve identifying parts of the population estimates that were under- or over-estimated between 2012 and 2020, using 2021 Census data and other sources. In Scotland, 2022 Census data will be used to rebase the Scottish population estimates between 2012 and 2021.

It is expected that population estimates rebased following the 2021 Census (for England, Wales and Northern Ireland) will be available from late 2022. Similarly, for Scotland, population estimates rebased following the 2022 Census are expected to be available from late 2023. These rebased population estimates will be needed to produce the projections after the census.

National population projections (NPPs) are usually published every two years largely because of the uncertainty in demographic behaviour, the majority of stakeholders prefer a two-year cycle and their production is resource intensive.

This section outlines different options around timescales for the next set of projections and issues to consider. However, we do not envisage producing all three (2020, 2021 and 2022) sets of projections. The information in this section and the questions in Section 6 should help you provide informed feedback on your preference for population projections.

Different options on timescales for the next set of projections

2020-based national population projections

Potential date of release – late 2021 or early 2022: these would be based on the latest mid-year 2020 population estimates, which are rolled forward from the 2011 Census. They could use the assumptions used in the 2018-based NPPs or they could be updated to include the latest assumptions on future levels of fertility, mortality and migration, if that were possible.

2021-based national population projections

Potential date of release – 2023: these would be based on 2021 Census data for England, Wales and Northern Ireland, and the latest mid-year population estimates for Scotland rolled forward from the 2011 Census. They would be updated to include the latest assumptions on future levels of fertility, mortality and migration.

Please note, the approximate date of release is dependent on the availability of the revised mid-year estimates for England, Wales and Northern Ireland and is also dependent on the census results aligning with the mid-year estimates for England, Wales and Northern Ireland.

2022-based national population projections

Potential date of release – 2024: these would include the 2022 Census data for Scotland and the latest mid-year population estimates for England, Wales and Northern Ireland rolled forward from the 2021 Census. They would be updated to include the latest assumptions on future levels of fertility, mortality and migration.

Please note, the approximate date of release is dependent on the availability of the revised mid-year estimates for Scotland and is also dependent on the census results aligning with the mid-year estimates for Scotland.

At the current time we are monitoring the implications of the coronavirus (COVID-19) pandemic across our demographic measures (including births, deaths and migration) and considering implications for future rounds of projections. The coronavirus has disrupted the collection of several data sources used in the production of population projections and has changed some demographic behaviour in the short-term. It is not yet clear how these short-term changes in behaviour might affect long-term trends. This will be reviewed along with delays in data collection, as part of the planning process for the next set of projections.

These changes will inform decisions on future publication dates, as well as the assumptions that feed into the projections. As more data become available, and depending on user need, it may be possible to produce a specific variant in order to try to take account of the coronavirus in projections.

National population projections

National population projections (NPPs) are produced by age and sex for the UK and its constituent countries and are usually published every two years. The National Statistician and the Registrars General for Scotland and Northern Ireland commission the Office for National Statistics (ONS) to prepare and produce NPPs on their behalf.

The projections are based on the latest mid-year population estimates together with assumptions of future levels of fertility, mortality and migration. The primary purpose of the projections is to provide information on potential future population levels. They are used as a common framework for national planning in several different fields.

The NPPs are published for each of the four UK nations and we work closely with our partners in the devolved administrations, including discussing appropriate methods. We do this via our twice-yearly NPP committee meetings, as well as ongoing liaison.

The main focus of the national projections is the next 25 years from the base year, though we also produce longer-term projections up to the next 100 years. The uncertainty of population projections increases the further they are carried forward and particularly so for smaller geographical areas and age-sex breakdowns. In addition to the principal projections, we also make available variant projections, based on alternative assumptions of future fertility, mortality and migration.

The table of contents tool contains links to our full range of data and documentation from our latest release, the 2018-based NPPs. It lists all the datasets available (over 200) and allows you to filter by variable and geography. You can also access methodological information and all related background information associated with the 2018-based publication.

The 2018-based NPPs’ methods include demographic assumptions on future levels of fertility, mortality and migration, (see Table 2 on changes to long-term assumptions in UK projections). These assumptions are not predictions of the future, but plausible scenarios based on what has happened in the past. The ONS agrees important decisions in the NPPs production process with the NPP committee, which consists of the ONS, the Welsh Government, National Records of Scotland (NRS) and the Northern Ireland Statistics and Research Agency (NISRA).

We produce assumptions for future levels of fertility, mortality and migration by reviewing what has happened in the past and modelling plausible future scenarios. We also consult with a panel of independent academic experts working in the field of demography to discuss the possible forces that may influence future demographic behaviour.

The expert panel does not have any direct influence over the final assumptions, and the decisions lie with the NPP committee. Our consultation with the experts over three to four weeks allows us to make informed decisions on the plausibility of proposed assumptions and presents an opportunity for us to validate our proposed assumption-setting methodologies.

Final demographic assumptions are produced by the ONS and are approved by the NPP committee once they are satisfied with the robustness and plausibility.

For more information on the NPPs, please see:

• ONS release on the latest 2018-based national population projections
• NRS release summarising the projections for Scotland
• NISRA release summarising the projections for Northern Ireland
• WG release summarising the projections for Wales

Subnational population projections

Subnational population projections (SNPPs) are produced by age and sex usually every two or three years and are produced after the production of the equivalent NPPs as they use the NPP assumptions. They provide an indication of the possible size and structure of the future population, based on the continuation of recent demographic trends, and are produced on a consistent basis for local and health authorities, and national parks.

SNPPs are produced by the appropriate organisation for each part of the UK: the ONS (for England), the Welsh Government, NRS (Scotland) and NISRA (Northern Ireland).

The methods for producing population projections are similar across the UK but differences in requirements and data availability in the various parts of the UK mean that slightly different approaches are adopted when producing the subnational projections. More information is available in Subnational population projections across the UK: a comparison of data sources and methods.

For more information on the SNPPs, please see:

• ONS release on subnational population projections for England: 2018-based
• NRS release on 2018-based population projections for Scottish areas
• NISRA release on 2018-based population projections for areas within Northern Ireland
• WG release on 2018-based population projections for Welsh areas

Wales

SNPPs for Wales are available from the Welsh Government by single year of age (up to 90 years and over) and by sex for each local authority and national park area.

Projected components of change are also published on the StatsWales website for each local authority and national park area.

Scotland

SNPPs for Scotland are available from NRS by single year of age (up to 90 years and over) and by sex for each area. Tables summarising population change, components of change, fertility rate, life expectancy, and fertility and mortality scaling factors for each area are also published.

Additional detailed tables are also made available on request, providing projected components of change (births, deaths and migration) by single year of age and sex for each area.

Data are also published on Scotland's Open Data Platform (for official statistics).

Northern Ireland

SNPPs for areas within Northern Ireland are available by single year of age (up to 90 years and over) and by sex. Additional tables provide projected components of change (births, deaths and migration) for each area.

Data are also published on OpenDataNI, a digital portal created to facilitate access to Northern Ireland public sector data for both reuse and redistribution.

Household projections

The household projections use the SNPPs as their base, and it is anticipated that they will be published approximately six months after the release of the SNPPs. The ONS is not planning to produce 2020-based household projections and so the next set of household projections for England will likely be either 2021-based or 2022-based. Decisions on timescales for future household projections have still to be taken by the devolved administrations and will be informed by feedback from users on preferences for the next set of NPPs and SNPPs.

To determine the best route forwards on publication of national population projections and subnational population projections please provide us with your comments on the following:

1. What are your preferences around the timescales for future projections? Do you need 2020-based national and/or subnational population projections (please state when you would ideally need them) or would you prefer to wait until census data can be included? Do you have preferences for 2021- or 2022-based projections?

2. Why do you require national and/or subnational population projections? How will you use these?

3. What specifically do you require from national and/or subnational population projections? Please list any specific variant projections (excluding non-National Statistics variants) and tables that you require (from the list of variants). If it is possible, would a variant projection that potentially reflects the coronavirus (COVID-19) be beneficial?

4. Could a shorter release containing only datasets and information on how the assumptions were set meet your needs? (that is, without an accompanying statistical bulletin summarising the main findings).

5. What effect would it have on your use of 2020-based projections if it was decided to re-use 2018-based assumptions because of uncertainty over short- and longer-term demographic trends arising from the coronavirus (COVID-19)?

6. Do you have any other comments on national or subnational population projections?

We welcome feedback on the questions presented in Section 6. Please send your comments via email to Population.Statistics@ons.gov.uk by 12 November 2020, indicating in the title of your email that you are responding to the user engagement on population projections and who you are representing. Your response may be shared with our partners, (National Records of Scotland (NRS) for Scotland, Northern Ireland Statistics and Research Agency (NISRA) for Northern Ireland and the Welsh Government (WG) for Wales). All responses will be treated in accordance with our stakeholder privacy notice.

Please include the following information in the main text of your response:

• your name
• organisation (if applicable)
• who you are representing
• your main use of population projections data
• email address

Thank you for taking the time to respond. A response to this user engagement is planned for publication by the end of the year and any decisions made as a result of user feedback will follow.

National population projections, how the assumptions are set: 2018-based
Article | Released 21 October 2019
Provides a summary of how we made our decisions when setting the fertility, mortality and migration assumptions for the 2018-based national population projections.

National population projections, variant projections: 2018-based
Article | Released 21 October 2019
The variant projections, a range of scenarios with alternative demographic assumptions, used in the 2018-based national population projections.