Migration Statistics Quarterly Report: July 2018 (rescheduled from May 2018)

Migration is a complex issue and to fully understand it we need to consider all information. Our best assessment shows around 280,000 more people coming to the UK than leaving in 2017, so net migration has continued to add to the UK population.

Net migration has fallen following record levels in 2015 and early 2016, and has been broadly stable since. This is similar to the level recorded in year ending September 2014. Underlying this, immigration has remained broadly stable at around 630,000 and emigration has shown a gradual increase since 2015 and is currently around 350,000.

Our assessment is that net migration has been broadly stable over the last year. Although the Long-Term International Migration (LTIM) estimates show an increase in net migration over the latest year, this is due to an unusual pattern in the estimates for student immigration in 2016, which was not seen in other sources and which our quality work suggests is an anomaly.

The number of non-EU citizens coming to the UK to study has remained relatively stable over the past few years based on an assessment of the International Passenger Survey (IPS), Home Office data on long-term study visas and Higher Education Statistics Agency (HESA) data together.

EU net migration continues to add to the UK population with around 100,000 more EU citizens coming to the UK than leaving. The estimated number of EU citizens coming to the UK “looking for work” continued to decrease over the last year and the number coming to the UK for a definite job has remained stable.

Since 2014, non-EU IPS estimates and Home Office data on long-term work visas show those coming to the UK to work have remained relatively stable, with increases for those on skilled work visas.

Important points for interpreting figures in this bulletin

Throughout this release we have used all available sources of information to come to our best assessment of what is happening to migration. Sources used include: Higher Education Statistics Agency data, Home Office administrative data and DWP information on registrations for new National Insurance Numbers (NINos) (although we acknowledge this last source will also have short-term migration within it and is used with caution). The full rationale for this approach is explained in the Report on international migration data sources, which sets out our latest understanding of the quality of migration estimates.

International Passenger Survey (IPS) estimates for year ending September 2016 saw a decrease in the number of non-EU citizens arriving to study, which was not reflected in the most comparable Home Office student visa data or Higher Education Statistics Agency (HESA) first year student enrolments data. Because of this unusual pattern we encourage users to look at the broader evidence and longer time series, which offers our best interpretation of long-term student immigration.

As announced in May, a survey processing issue was identified with the IPS. An independent assurance group was formed to fully investigate the issue so that we can be confident that the Long-Term International Migration (LTIM) and IPS numbers presented in the release are correct. Home Office and Department for Work and Pensions data were published in May as usual.

A thorough quality assurance process revealed that the already published year ending September 2017 estimates were also affected by the processing issues and years ending June 2017 and September 2017 were affected by a weighting correction (see part 2 of the Report on international migration data sources for further details).

The latest LTIM and IPS estimates included in this bulletin include corrections to the years ending June 2017 and September 2017, as well as the latest figures for 2017. A full set of corrected data is available in the accompanying datasets and tables.

Progress with our Government Statistical Service programme means that starting from this release we are providing a broader picture of migration trends based on all available sources.

This quarter we also released a blog to explain more about this latest release and how our transformation programme is making a difference.

“With around 280,000 more people coming to the UK than leaving in 2017, these latest figures show that migration has continued to add to the UK population. Net migration fell following record levels in 2015 and early 2016 and has been broadly stable since. This is similar to the level recorded in year ending September 2014.

“Underlying this immigration has remained broadly stable at around 630,000 and emigration has shown a gradual increase since 2015 and is currently at around 350,000.”

Nicola White, Migration Statistics Division, Office for National Statistics.

Follow ONS Director of Migration Statistics @JayLindop_ONS

The reporting period for the International Passenger Survey (IPS) and Long-Term International Migration (LTIM) data in this release is year ending December 2017. Entry clearance visas and other Home Office statistics, National Insurance Number (NINo) and labour market data are available to the end of March 2018.

Complexities of measuring international migration

Traditionally migration statistics have been designed to feed into population estimates as an important component of change and aligned to be consistent with the United Nations (UN) definition of an international migrant. In recent years the demand for information on migration has increased. There is now much more interest in the characteristics of migrants who reside in the UK and the impact they have on the economy and society. There are sources of data that shed some light on this but these only go so far in meeting the needs of the public, media and policymakers with no one source of data providing a full picture.

Our traditional definitions of Long-Term International Migration and Short-Term International Migration do not match the complexity of people’s lives and their movement between countries and the traditional definition of an international migrant is becoming less relevant.

A richer picture is needed that considers circular migration (PDF 568KB), for example, or repeat migration, which is the temporary and usually repetitive movement of a migrant worker between home and host areas, typically for the purpose of employment. It represents an established pattern of population mobility, whether cross-country or rural-urban.

Government statisticians have been responding to these changing needs by collaborating and sharing data across government to improve the information that is currently available and we have set out our plans in a transformation work programme.

Each source of data has a valuable contribution to make in understanding international migration. The challenge is in piecing together the different parts of the puzzle that make up this complex and important topic. Differences arise between these sources as a result of the way our data collection processes operate and the definitions we use. These are described in the summary note Comparing sources of international migration statistics.

ONS have long acknowledged the limitations of the International Passenger Survey (IPS) and that it has been stretched beyond its purpose. In this release we have made two developments to start the journey of transforming the way we present estimates of international migration.

This release includes an overview of migration trends based on our best assessment of available administrative and survey data. The sources of data included in this release are not directly comparable but taken together give a better indication of trends than any single source alone. This assessment is included as well as our usual information on Long-Term International Migration (LTIM) and the IPS. As we continue to improve our understanding of administrative data, our future reporting will aim to integrate evidence from further sources, where appropriate.

We have also included a new approach to our charts that aims to give a clearer illustration of the uncertainty associated with the IPS estimates. We will be looking to develop this further. So as part of our transformation programme we will be working with the University of Cambridge to explore how best to show the uncertainty associated with both survey and administrative data sources that measure the different elements of migration and how to explain this to our wide range of users through user testing.

International Passenger Survey (IPS) correction and assurance

On 17 May 2018, we postponed the regular quarterly long-term migration statistics because of survey processing issues. The Report on international migration data sources provides full details of the now complete review and assurance process carried out to ensure that the IPS data and the migration statistics produced are at the quality required.

The investigation traced the issue with the data to the temporary processing change that was implemented. The issue does not relate to data collected from new tablets but to processing of the remaining paper questionnaires. The issue was identified and corrected in the October to December 2017 data.

To ensure full confidence in the data and to allow further review of the recent changes implemented in the IPS data collection and processing systems, an independent assurance review was commissioned. The overall impact of the review and subsequent corrections to the data include:

• a delay in the release of year ending December 2017 IPS and LTIM estimates (published 16 July 2018)
• correction of the July to September 2017 IPS dataset and to the year ending September 2017 IPS and LTIM estimates (published February 2018)
• minor corrections to the April to June 2017 IPS dataset and to the year ending June 2017 IPS and LTIM estimates (published November 2017)

The net effect of these changes are published in the Report on international migration data sources but in summary the corrections saw changes to the published estimates across headline measures of immigration, emigration and net migration as follows:

• a decrease for year ending June 2017
• an increase for the year ending September 2017

The net migration estimate for the year ending June 2017 was used in the production of the latest population estimates, which were published on 28 June 2018. The difference between the corrected net migration estimate and the net migration estimate used for the mid-2017 population estimates was 4,000. As such this change has no impact on the estimate of 66 million for the UK population.

Alongside the review of the IPS data and following an unusual pattern in the estimated number of non-EU citizens arriving to study reported in the February Migration Statistics Quarterly Report (MSQR), we also carried out an integrated assessment of all the sources available. We collated available administrative data for comparison with and validation of the IPS and LTIM estimates to ensure our full understanding of the migration story using all the available data. This assessment is included in this release.

The unusual pattern in the year ending September 2016 data was mainly accounted for by those arriving in the UK for study, which was not reflected in the comparable Home Office student visa data nor the Higher Education Statistics Agency data (see section 4 for further information).

In carrying out the assurance review we confirmed that the IPS is more susceptible to sampling variability for students as most students arrive at the start of the academic year creating a cluster effect. Depending on the shifts selected for the IPS sample, it may or may not include clusters of students and so the variability in the subsequent estimates may be increased.

Administrative data allows us to compare trends and has been important in helping us further understand this variability. We are not formally adjusting LTIM or IPS estimates but using administrative data to provide a broader overview of migration trends. Administrative data can cover different types of migration, for example: some data sources only cover those coming to the UK to work and others only cover those coming to study, so each data source will only be able to report on certain types of migration. Currently we have minimal data to compare EU and British citizens against. Once we acquire data that covers all citizenships and develop our understanding of this data we can make a wider set of comparisons across migration in all its elements.

Definitions and terms

Office for National Statistics (ONS) migration statistics use the UN recommended definition of a long-term international migrant: “A person who moves to a country other than that of his or her usual residence for a period of at least a year (12 months), so that the country of destination effectively becomes his or her new country of usual residence.”

The Long-Term International Migration (LTIM) estimates methodology describes how data from the IPS and other sources are used to create LTIM estimates. LTIM estimates are based on IPS data, but with additional adjustments made for migrants not included in the survey, such as asylum seekers. Some estimates are only available based solely on IPS data. Differences between ONS, Home Office, Department for Work and Pensions (DWP) and other sources are described in Comparing sources of international migration statistics.

Because of the nature of illegal migration it is not possible to quantify accurately the number of people who are in the country illegally. For this reason, we do not produce estimates on the size of the illegal migrant population. However, while our data do not identify illegal migrants separately, some will be included in the stocks and flows of migrants in our data.

Specific notes for this release:

• all of the LTIM and IPS estimate changes detailed in the release are statistically significant unless specifically stated otherwise
• EU estimates exclude British citizens; citizens of countries who were EU members prior to 2004, for example France, Germany and Spain, are termed the EU15; Central and Eastern European countries who joined the EU in 2004, for example Poland, are the EU8; EU2 comprises Bulgaria and Romania, who became EU members in 2007
• rolling year estimates for LTIM and IPS are produced quarterly for year ending (YE) March (Quarter 1), YE June (Quarter 2), YE September (Quarter 3) and YE December (Quarter 4)
• LTIM and IPS data for 2017 are provisional; there is minimal change between provisional and final data

Full details of terms and definitions can be found in the International Migration – terms, definitions and frequently asked questions.

Including administrative data in our analysis provides users with a broader overview of migration trends. Although the data sources are not directly comparable, they provide users with our best assessment of migration. Administrative data allows us to compare trends and has been important in helping us further understand the International Passenger Survey (IPS) trends.

In 2017, net migration (the difference between those coming into the UK and those leaving the UK) is positive, meaning that international migration is adding to the UK population – with an estimated 282,000 more people arriving in the UK than leaving (Table 1).

Although the IPS shows an increase in net migration compared with the previous year, this is because of an unusual pattern for students in 2016 in the IPS, which was not seen in other sources and which our quality work suggests is an anomaly. Hence, our best assessment of net migration shows that it has fallen following record levels in 2015 and early 2016. It has been broadly stable since and similar to the level recorded in year ending September 2014. Underlying this, immigration (630,000) has remained broadly stable and emigration (349,000) has shown a gradual increase since 2015.

Figure 1 shows the trend of the latest Long-Term International Migration (LTIM) estimates. This immigration and net migration series includes an illustrative revised trend to adjust for the unusual pattern in IPS non-EU student immigration in year ending September 2016. Further details of this adjustment are included later in this section.

Figure 1: Long-Term International Migration, UK, 2008 to 2017

The change in immigration in 2016 and 2017 has been analysed further using administrative data sources for the various reasons for migration to understand the patterns we are seeing, in particular for students.

Assessing long-term study trends using available administrative data sources

For non-EU students we can compare the International Passenger Survey (IPS) trends to Home Office student visa data and Higher Education Statistics Agency (HESA) first year student enrolment data for 12 months or more. None of these data sources will exactly align because of definitional and coverage differences but they provide a broad picture of the patterns.

Home Office visa and HESA data show that non-EU long-term student immigration has remained stable since 2013, which contrasts with the unusual pattern in the IPS non-EU student immigration estimate, as reported in February 2018. In the year ending September 2016, we saw a decrease in the estimated number of long-term non-EU citizens arriving in the UK to study, whereas in the year ending September 2017 this estimate has increased back to levels seen in early 2015 (Figure 2). Our best assessment, using all available data sources, of non-EU long-term student immigration is that it has remained relatively stable over the past few years. We encourage users to look at the broader evidence and longer time series when using these data.

In carrying out the IPS assurance review we highlighted that the IPS is more susceptible to sampling variability for students as most students arrive at the start of the academic year creating a cluster effect. Depending on the shifts selected for the IPS sample, it may or may not include clusters of students and so the variability in the subsequent estimates may be increased. This results in the fluctuating trend of long-term IPS non-EU student immigration (Figure 2).

As such, we have produced an illustrative revised trend for the IPS non-EU student immigration estimate. We have limited administrative data to compare EU citizens against (as EU nationals do not require a visa), so the illustrative revised trend has only been made for long-term non-EU students.

For year ending September 2016 estimates onwards we have taken the year-on-year percentage change of Home Office visa data and applied this rate of change to the IPS estimates. The illustrative revised trend shows a relatively stable pattern over this time period for IPS non-EU student immigration and brings the IPS estimate back to a similar level as reported in year ending September 2017 and December 2017 (Figure 2).

It is likely the illustrative revised trend would be slightly higher if EU students were included. To make an adjustment to the overall IPS student immigration estimate we need a better understanding of all citizens immigrating to study, as such only an illustrative revised trend for non-EU student immigration is provided.

Figure 2: Non-EU long-term student immigration trends by data source, 2008 to 2017

Published Home Office visa figures for students include both long- and short-term immigrants and are available for year ending March 2018. The latest research on understanding international student migration was published in August 2017. Differences between ONS and Home Office data are explained further in Comparing sources of international migration statistics.

In 2017, non-EU net migration (+227,000) was twice the level of EU net migration (+101,000) (Figure 3).

Figure 3: Net migration to the UK by citizenship, UK, 2008 to 2017

The number of EU citizens coming to the UK in 2017 was 240,000. This was lower than levels seen in 2015 and 2016 but is at a similar level to mid-2014. The number of EU citizens leaving the UK was 139,000, similar to the year ending September 2017 estimate (137,000) and year ending December 2008 (134,000). As a result, EU net migration is at a similar level to year ending June 2013, with around 101,000 more EU citizens coming to the UK for 12 months or more than leaving for 12 months or more.

Non-EU immigration (311,000) is similar to the level seen in 2011. As noted in section 4, the latest increase follows a low level of non-EU study immigration in the year ending September 2016, which was not reflected in the most comparable visa and Higher Education Statistics Agency (HESA) data. We advise users to avoid looking at the latest year on year change for students and instead look at the broader evidence and longer time series showing that non-EU student immigration has remained relatively stable over the past few years. Non-EU net migration is similar to the level seen in year ending September 2011 and the illustrative revised trend to adjust for the usual pattern in student immigration can be seen in Figure 3.

More detailed Long-Term International Migration (LTIM) estimates of immigration, emigration and net migration by citizenship over time, along with confidence intervals around all the estimates can be found in Table 1 and Chart 1TS in the accompanying datasets.

Assessing trends for all work-related immigration

In 2017, the Long-Term International Migration (LTIM) estimate of the number of people coming to work in the UK was 269,000, similar to the previous year. The majority came to the UK with a definite job (193,000) whilst the rest arrived looking for work (76,000) (Table 3). Since 2015, the number of people arriving for a definite job has remained relatively stable and since year ending June 2016 the number of people arriving in the UK looking for work has declined.

As with students we can use administrative data to look at the more detailed picture of work-related immigration. To work in the UK, a person requires a National Insurance Number (NINo) and, if a citizen from a non-European Economic Area (EEA) country, a valid work visa (dependent on type of work and length of stay).

NINo registrations to foreign nationals published by the Department for Work and Pensions (DWP) are available for all nationalities and include both short- and long-term migrants. So the figures are much higher than The ONS estimates and Home Office visa data, which makes it difficult to make any meaningful comparisons. Although not directly comparable they can provide useful insights into trends for different nationalities¹.

According to the IPS work-related immigration estimates, just over half are EU citizens and around a third are non-EU citizens.

Non-EU immigration for work-related reasons

The number of Home Office work visas issued for 12 months or more can be compared with the long-term International Passenger Survey (IPS) non-EU work-related immigration estimates. Over the last few years these data sources have shown similar trends and remained relatively stable, although prior to 2014 there seems to have been more of a difference between the two series (Figure 4). The latest increase in the IPS non-EU work-related immigration estimate is not reflected in the visa data and may be related to sampling variability. We will continue to monitor how these sources relate to each other over the coming quarters.

Non-EU NINo figures are also included to show their trend but will include short-term migrants and people who may have been in the country a while before applying for a NINo. Over the last few years these figures have remained stable following a fall between 2010 and 2014 (Figure 4).

Figure 4: Non-EU long-term work-related immigration trends by data source

UK, 2008 to 2017

In 2017, the IPS estimate of non-EU citizens coming to the UK for work-related reasons (87,000) increased 21,000 compared with the previous year. This increase was driven by Asian (up 12,000), particularly South Asian (up 8,000) citizens. The overall increase in non-EU work-related immigration is also mostly accounted for by those coming to the UK for a definite job (up 18,000), particularly Asian nationals (up 10,000). However, the latest increase is not reflected in the administrative data sources and may be a consequence of sampling variability. We will continue to monitor how these sources relate to each other over the coming quarters.

In 2017, there were 77,000 Home Office work-related visas issued for 12 months or more to non-EU nationals, similar to the previous year, and 185,000 NINo registrations from non-EU nationals (down 7% over the year). Note that NINo registrations include short-term migrants and people who may have been in the country a while before applying for a NINo, hence the higher figure.

EU immigration for work-related reasons

As EU citizens do not require a visa to work in the UK, IPS long-term EU work-related immigration and NINos trends were assessed (Figure 5).

In 2017, the number of EU citizens coming to the UK for work-related reasons was 141,000, down 20,000 compared with the previous year (not statistically significant). There were 497,000 NINo registrations from EU citizens (down 21% over the year) in 2017, including 188,000 EU15, 113,000 EU8 and 193,000 EU2. Most of this difference is likely to be accounted for by short-term migrants included in the NINos and people who may have been in the country a while before applying for a NINo.

Figure 5: EU long-term work-related immigration trends by data source, UK, 2008 to 2017

Of the 141,000 long-term EU citizens coming to the UK for work-related reasons, 37,000 were looking for work, a decrease of 18,000 compared with the previous year. The number of EU citizens coming to the UK looking for work has been declining since year ending June 2016, driving the decrease in overall looking for work. The number of EU citizens coming for a definite job (104,000) has remained the same as the previous year (Figure 6).

Figure 6: EU and non-EU immigration to the UK for work-related reasons, UK, 2008 to 2017

EU nationals more likely to be in employment than UK and non-EU nationals

Estimates of the labour market activity of the resident population in the UK by nationality and country of birth are published quarterly and measure the net change in employment, unemployment and inactivity. They are not designed to provide a measure of migration flows. Changes in the labour market stock cannot be directly compared with long-term net migration, and so the best measure of total migration flows into and out of the UK is the International Passenger Survey (IPS) and the LTIM estimates.

These statistics are derived from the Labour Force Survey up to the latest period, that is, January to March 2018. The latest estimates show that²:

• there were 2.29 million EU nationals working in the UK, 28,000 less than a year earlier (the first annual fall since 2010)
• there were 1.25 million non-EU nationals working in the UK, 20,000 more than for a year earlier
• the employment rate (the proportion of people aged from 16 to 64 years who were in work) was 81.9% for EU nationals, higher than that for UK nationals (75.6%) and higher than that for non-EU nationals (63.0%)

Further details of work-related data

More detailed estimates over time by main reason for migration can be found for LTIM in Table 2 and by citizenship and main reason for IPS in Table 3 in the accompanying datasets.

The Home Office Immigration Statistics release includes both short-term and long-term visas (including dependants) and is available for year ending March 2018. The release includes more detailed statistics by visa category, citizenship and industry sector.

National Insurance number allocations to adult overseas nationals includes both short-term and long-term visas and are available for year ending March 2018. The summary tables provide more detail by nationality and location of registrations in the UK. Further information including detail on data sources, uses and limitations of the series is provided in the background information.

Differences between the data sources are described in Comparing sources of international migration statistics.

Notes for: Work is the most common reason people come to the UK

1. National Insurance number (NINo) registrations and IPS estimates are not directly compared. The figures are based on the recorded registration date on the National Insurance Recording and Pay As You Earn System (NPS) (after the NINo application process has been completed). See note on the difference between NINo and long-term international migration.

   NINo allocations to adult overseas nationals and nationality at point of NINo registration of DWP working age benefit recipients (NINo benefit claimants) are no longer badged as National Statistics. The statistics continue to be published as official statistics following Office for Statistics Regulation reassessment of the statistics. The full assessment can be found on the UK Statistics Authority website in a report on the reassessment of the NINo statistics.

2. Statistical significance testing is not available for EU and non-EU breakdowns.

Long-Term International Migration estimates are adjusted to include refugees and asylum seekers.

In the year to March 2018, there were 14,166 grants of asylum, alternative forms of protection and resettlement (42% of which were granted to those under 18 years of age), compared with 15,973 the previous year. This comprised of:

• 6,865 grants of asylum to main applicants and dependants (down 17%)
• 1,541 grants of alternative form of protection to main applicants and their dependants (up 16%)
• 5,760 people provided with protection under a resettlement scheme (down 9%)

Additionally, 5,874 family reunion visas were issued to partners and children of those granted asylum or humanitarian protection in the UK, a 2% increase since last year.

These data are provided by the Home Office and more detailed statistics and underlying data on asylum and protection can be found in the Home Office Immigration Statistics release.

As ONS set out in September 2017, the context for our work is changing. Our role as independent government statisticians is to meet the demand from users of the statistics – in this case, a clear understanding of the latest trends in international migration and improving the evidence base to provide more information on the impact migrants have while they are in the UK. That includes the sectors in which they work, the communities they live in and the impact they have on public services. This programme of work therefore forms one piece of a larger Government Statistical Service (GSS) transformation plan to meet these user needs and which will begin to put administrative data at the core of evidence on migration. We provided an update on these plans in May 2018.

The exploratory research in part 1 of the Report on international migration data sources sets out what we have undertaken so far this year. Working collaboratively with Home Office experts has given us a better understanding of non-EU migrants across the different visa routes (study, work and family). This analysis is helping to increase our understanding of the quality of the International Passenger Survey (IPS) long-term immigration and emigration estimates for non-EU migrants who originally came to the UK for 12 months or more, and better understand the different patterns of migrants’ journeys.

This research, based on two years’ worth of Home Office administrative data has highlighted:

1. Migration is complex and no single source on its own can provide the whole picture.

2. Understanding migration patterns utilising administrative data is complicated. Comparisons of administrative data against the International Passenger Survey (IPS) show a difference in figures but there are a multitude of reasons for this including the fact that the data sources are measuring different things – intentions (IPS) versus actual travel (administrative data). No single source of information will provide a clear view of migration; therefore, our transformation programme aims to triangulate the multiple sources to build a more comprehensive and granular evidence base for migration in the UK.

3. A level of flexibility in the approach is needed when designing a method for understanding migrant travel patterns, since analysis of Home Office administrative data illustrates that using one set of assumptions to calculate length of stay is not appropriate for all migrants – their lives are complicated and their travel patterns differ.

4. Aligning to the United Nations definition of a long-term migrant is becoming more challenging and access to administrative data has allowed us to build a clearer picture of migration patterns. For example, allowing us to understand more about temporary or circular migration, which isn’t currently possible using the IPS.

5. Exploratory research utilising Home Office administrative data relates to non-EU migrants and we cannot, therefore, draw conclusions about net migration as a whole. More research is needed to look at EU and British migration as part of our wider transformation programme.

This exploratory research, published today, has been complex and multi-faceted with the research we have been doing using Home Office administrative data being one component of the programme. Moving forward there is much more work to do on understanding how migrants interact with administrative data sources, to fully understand how these might be used to enhance migration statistics. As we continue to improve our understanding of administrative data, our future reporting will aim to integrate evidence from further sources, where appropriate.

This publication is one of a suite of migration-related statistics and analysis, which together give a more comprehensive view on migration to and from the UK.

Alongside this release are accompanying datasets relating to Long-Term International Migration and International Passenger Survey only estimates.

On 24 May 2018, the regular quarterly outputs across the Government Statistical Service were released:

• Home Office Immigration statistics, year ending March 2018
• Department for Work and Pensions National Insurance number allocations to adult overseas nationals to March 2018

Today (16 July 2018) we also release:

• Report on international migration data sources
• The latest migration figures: what’s new about them and what do they say

If you are new to migration statistics, you might find it helpful to read the International migration statistics first time user guide.

If you would like to subscribe to our newsletter, please send an email to pop.info@ons.gov.uk with the subject title “Subscribe to ONS Population Statistics Newsletter”, or you can also follow our Director of Migration Statistics @JayLindop_ONS on Twitter for the latest population statistics news and updates and to join in the conversation.

The Long-Term International Migration Quality and Methodology Information report contains important information on:

• the strengths and limitations of the data and how it compares with related data
• uses and users of the data
• how the output was created
• the quality of the output including the accuracy of the data

For more detailed information on our migration statistics methodology please see International migration methodology.

IPS Assurance Review

The International Passenger Survey (IPS) data assurance review is published alongside the Migration Statistics Quarterly Report today, 16 July 2018 in section 2 of the Report on international migration data sources.

A note on the accuracy of long-term migration estimates

Surveys gather information from a sample of people from a population. Using the International Passenger Survey (IPS) as an example, the population is passengers travelling through the main entry and exit points from the UK including airports, seaports and the Channel Tunnel. The estimates produced are based on only one of a number of possible samples that could have been drawn at a given point in time. Each of these possible samples would produce an estimated number of migrants. These may be different from the true value that would have been obtained if it were possible to ask everyone passing through about their migration intentions. This is known as sampling variability.

A confidence interval is a measure of the uncertainty around the estimate. Confidence intervals are reported in the accompanying datasets. Users are advised to be cautious when making inferences from estimates with relatively large confidence intervals. For immigration and emigration estimates where the lower confidence interval is below zero, users should assume the estimate is above zero. Estimates from a survey could change from one period to the next simply because of sampling variability. In other words, the change may be because of which individuals were selected to answer the survey and may not represent any real-world change in migration patterns.

For further information on confidence intervals, the accuracy of these statistics, comparing different data sources, and the difference between provisional and final figures, please see International migration methodology.

The quality of the long-term student migration statistics – former student emigration estimates are now labelled as Experimental Statistics. As part of the ONS work plan on student migration, the latest research on understanding international student migration was published in August 2017. This report focuses on analysis of Home Office administrative data for non-EU students and the results of a new student survey exploring student intentions on completion of study.

Revisions to net migration estimates in light of the 2011 Census

In April 2014, we published a report examining the quality of international migration statistics between 2001 and 2011 (PDF 1037KB), using the results of the 2011 Census. As a result, we published a revised series of net migration estimates for the UK. Published tables have been updated to include the revised estimates. The report, a summary and guidance (PDF 56KB) on how to use these revised figures are available. No revisions were made to separate immigration and emigration estimates at the time the net migration estimates were revised.