1. Introduction

This guide is designed as an introduction to the main concepts that underpin migration statistics. There are a number of sources of data on migration and advice is provided on where to find these, as well as links to publications that can offer further information. There is also a glossary of the main terms used throughout our migration statistics outputs and a list of products containing the most important links for the outputs.

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2. Who is an international migrant?

There are a number of ways to define an international migrant. We publish statistics on both Long-Term International Migration (LTIM) to and from the UK and Short-Term International Migration (STIM) to and from England and Wales.

A long-term international migrant is “a person who moves from their country of usual residence for a period of at least 12 months” (UN definition).

A short-term international migrant is “a person who moves to a country other than that of his or her usual residence for a period of at least 3 months but less than a year except in cases where the movement to that country is for purposes of recreation, holiday, visits to friends and relatives, business, medical treatment or religious pilgrimage” (UN definition).

The UN definition of a short-term international migrant therefore focuses on those migrating for work or study. We also publish short-term international migration statistics for those migrating for 3 to 12 months for all reasons for migration and for 1 to 12 months for all reasons for migration.

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3. How has international migration changed over time?

Levels of both immigration and emigration are higher now than they were 50 years ago. In the 1960s and 1970s, approximately 200,000 people immigrated to the UK each year and around 250,000 people emigrated annually. In the 1980s, immigration began to exceed emigration on an annual basis. Since the late 1990s, the numbers of immigrants and emigrants has increased further, notably in 2004 when the EU expanded to include 10 new countries.

The International Migration Timeline shows Long-Term International Migration estimates from 1964 to 2015. It allows you to see the migration figures for broad citizenship groupings for particular years, in a wider context, as well as providing an historical picture of how migration has changed over the period.

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4. How is Long-Term International Migration (LTIM) measured?

Estimates of LTIM are about 90% based on data from the International Passenger Survey (IPS). This sample survey is conducted at all the main entry and exit points from the UK including airports, sea ports and at the Channel Tunnel.

To collect the data, a specific entry or exit point is sampled on a particular day. A strict method of counting is used, which ensures each person has the same opportunity of inclusion in the survey. Passengers are systematically selected for interview at fixed intervals (for example, every 1 in 20th person) from a random start.

Between 700,000 and 800,000 people are interviewed on the IPS each year. Of those interviewed, approximately 4,000 people each year are identified as long-term migrants. These are non-UK residents who state that they intend to stay in the UK for at least 12 months (immigrants) or UK residents who state that they intend to reside outside of the UK for at least 12 months (emigrants). The remainder are identified as either short-term migrants, visitors to and from the UK, or UK residents returning after or leaving for a short stay overseas.

To estimate LTIM, the IPS data are supplemented by:

  • Home Office data, which are used to calculate an adjustment for asylum seekers and their dependants, as well as for non-asylum enforced removals and people resettled in the UK under various resettlement schemes

  • an adjustment to add in visitor switchers and remove migrant switchers; these are people who change their intentions with regards to length of stay

  • Northern Ireland Statistics and Research Agency (NISRA) data on migration to and from Northern Ireland based on GP registrations, which are used to adjust for migration between the Republic of Ireland and Northern Ireland (land routes are not surveyed by the IPS)

Further information is available on Long-Term International Migration estimates methodology.

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5. How is Short-Term International Migration (STIM) measured?

Estimates of STIM are produced for England and Wales and for local authorities.

National estimates of STIM are produced directly from data from the International Passenger Survey (IPS). Estimates of short-term migration are available as flows (the total number of moves made over a set period) and stocks (the number of short-term international migrants present or absent at a given point in time).

Flow estimates refer to the number of migrations commenced (migrant moves) as opposed to the number of people who commence migrations (migrants). This distinction is important when estimating STIM annually because a person could migrate more than once in the same period. For example, a single person migrating twice in a year for 3 months on each occasion would appear in the short-term flow estimates as two (migrant moves), not as one (migrant).

Stock estimates are calculated by summing the number of nights each short-term migration lasts and dividing by 365 to create a long-term migrant equivalent. Where a short-term migration spans two time periods, the stay is split between the two periods.

It is not possible to calculate net migration for short-term migrants, as the definition of a migrant is different for the inflow (who must be a foreign resident moving to England and Wales) and the outflow (who must be a resident of England and Wales moving overseas).

Short-term migration statistics are based on interviews on the IPS at the end of their stay. This means that the estimates are based on actual behaviour, in contrast to Long-Term International Migration (LTIM) estimates, which are based on interviews conducted when the migrant arrives and are therefore based on the intended behaviour of migrants. There is therefore no need to adjust for migrant switchers or visitor switchers.

Asylum seekers are not included in STIM estimates as no suitable adjustments can currently be made. The adjustments used in LTIM are considered to be too complex to be applied to STIM, given the small numbers of migrants affected.

Local authority estimates for STIM are produced by distributing IPS estimates of short-term migrants who arrive in England and Wales for 3 to 12 months for work and study (which is the UN definition) to local authorities using administrative data.

Further information is available on Short-Term International Migration estimates methodology. This includes separate methodology documents for the national estimates and for the local authority estimates, as well as frequently asked questions.

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6. What is the difference between a flow and a stock?

Flows – the number of people migrating from one place to another over a given period of time. Long-Term International Migration (LTIM) and International Passenger Survey (IPS) estimates of long-term international migration are examples of migration flows.

Stocks – the number of people resident in the UK at a given point in time.

Population by Country of Birth and Nationality estimates are an example of stocks.

Data on flows, registrations and stocks may display apparently contradictory trends.

For example, it may be that the LTIM data indicate steady numbers of immigrants, but the National Insurance number (NINo) statistics show an increased number of successful registrations. However, the LTIM data describe people stating an intention to stay at least a year, whereas the NINo statistics include people who came to work in the UK for a short period of time (for example, for a summer job) and then left again. In addition, NINo allocations do not necessarily reflect a recent move to the UK at all, as an overseas national may already have been in the UK for several years (for example, as a student or a dependant) before they decide to seek employment.

Alternatively, the LTIM inflows and registrations data may suggest downward trends while the stock of people born outside the UK has gone up. This can be explained by a situation as follows.

Assume a starting point of 0 people from a particular country of birth in the UK. If 100,000 such people enter the UK in the first year (and all stay) but in the next year the inflow halves so only 50,000 enter (and all stay), the total stock would have risen to 150,000.

In other words, stocks of people born outside the UK can continue to rise despite reduced inflows, and only go down if the combined totals of emigration and deaths exceed immigration.

https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/internationalmigration/datasets/populationoftheunitedkingdombycountryofbirthandnationality

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7. Why have the former student emigration estimates been labelled as experimental?

Recently, a range of concerns about the robustness of the former student emigration estimate were raised with the Office for Statistics Regulation (OSR). As a result, OSR carried out a review of The quality of the long-term student migration statistics, which was published on 27 July 2017. The main focus of their report was the “student migration gap” – the difference between the estimate of the number of migrants entering the UK for formal study (student immigration) and the estimate of the number of former students leaving the UK (former student emigration).

The estimate of former student emigration is the only source of information about when a student leaves the UK. As a result, OSR were “concerned that the former-student emigration estimate does not bear the weight that is put on it in public debate. This estimate should add clarity on the pattern of student migration in the UK. Instead, it creates doubts by not providing a complete and coherent picture of former-student emigration, as these figures alone do not provide information on all the different outcomes for international students”.

OSR noted that “it is standard practice for new figures to be labelled as experimental while they bed in and it is unfortunate that this was not followed in this case when the new breakdown of emigration figures by previous reason for immigration was first introduced”. OSR therefore asked ONS to make clearer that this estimate should be treated with caution and that it be labelled as an experimental component of the overall National Statistics on migration, while the ONS work programme continues. This judgement applies only to the student migration component of ONS’s migration statistics; it is not a judgement about the quality of the overall estimates of immigration and emigration derived from the IPS.

As a result from 24 August 2017 we have labelled the former student emigration estimate as Experimental Statistics in all publications. Once we are satisfied that we have a sufficient understanding of former student outcomes, including the extent to which the IPS accurately captures student departures, we will request OSR to reassess the former student emigration estimate. Our latest understanding of student migration can be found in What's happening with international student migration?.

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8. Why do estimates of Long-Term International Migration differ from the number of National Insurance numbers allocated?

On 12 May 2016, we published an information note explaining the reasons why long-term international immigration figures from the International Passenger Survey (IPS) could differ from the number of National Insurance number (NINo) registrations. It noted that the two series are likely to differ because of short-term immigration and timing differences between arriving in the UK and registering for a NINo. It emphasised that the estimates derived from the IPS are the most appropriate for measuring long-term immigration. NINo registrations data are not a good measure of Long-Term International Migration (LTIM), but they do provide a valuable source of information to highlight emerging changes in patterns of migration.

The analysis used 1 to 12 month short-term migration estimates for employment, study and work (other) to help explain the gap as this group was most likely to contain people who might register for a NINo. In year ending June 2014, there were 251,000 EU citizens immigrating to England and Wales for 1 to 12 months for the reason of employment, study or work (other) compared with 239,000 the previous year. This is not the total level of Short-Term International Migration (STIM) but the most appropriate to help explain the gap. An ad hoc analysis was also run to estimate the number of short-term international migrants in 2015 using “intentions” data. Two estimates were included to reflect the uncertainty and the fact that they can be estimated in different ways. The article provides more information on this. The mid-2015 “actual” STIM estimates were published in May 2017.

Adding together LTIM and STIM estimates does not provide a reliable measure of all immigration to the UK within a specific time period. Short-term immigration flows are based on journeys, not people and have methodological differences from LTIM flows. In addition, it is possible for someone to be both a long-term and short-term migrant in the same period, and STIM estimates are based on actual flows whereas LTIM covers migrants' intentions.

However, although they cannot be added together to provide one single, accurate measure of international migration, LTIM and STIM estimates of immigration and emigration should be considered alongside and in the context of each other. As these estimates represent different people immigrating for different reasons, they can help to provide an overall picture of international migration. Historical data on short-term and long-term international migrants are published on our website, and there is a summary of the definitional differences between these data, which includes a NINo and IPS comparison.

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9. How reliable are the migration estimates?

As previously explained, Long-Term International Migration (LTIM) estimates are based primarily on data collected by the International Passenger Survey (IPS). Sample surveys like the IPS are used when we would like to know something about a population of individuals but asking all of them is impractical. For example, when we wish to know how many people are migrating into and out of the UK each year, one way to find this out would be to ask everyone crossing the UK border about their migration intentions. However, this would be a very expensive and impractical approach. Instead a more cost-effective approach is to use a sample survey.

As with all sample surveys, the estimates produced are based on only one of a number of possible samples of passengers that could have been drawn at a given point in time. Each of these possible samples would produce an estimated number of migrants, which may be different to the true value that would have been obtained if everyone passing through were interviewed. The published estimate for migration is the best available and most likely figure, based on the data collected of international migration flows during a particular time period.

By comparing the estimates from the IPS to other data sources, we can be confident that the IPS provides the best available estimates of international migration at the national level. For example, there was only a small (0.8%) difference between the 2001 to 2011 rolled-forward mid-year population estimates and the 2011 Census. This difference can be attributed to factors such as the accuracy of the 2001 population base in addition to migration, but the similar patterns of migration seen across other data sources (such as visas issued to citizens of countries outside the EU) provide reassurance that the IPS-based estimates at the national level provide reliable figures of international migration to and from the UK.

Since the IPS is based on a sample survey and not an exact count of passengers, it is good statistical practice to publish confidence intervals around the estimates. These provide a measure of the reliability of the estimates and can be used to identify statistically significant changes.

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10. What is a confidence interval?

The different possible samples of passengers that could have been selected on the International Passenger Survey (IPS) can be used to produce a sampling distribution for the figure we are trying to estimate. For example, if we are estimating immigration within a particular year, one sample may produce an estimate of 500,000, another may have resulted in an estimate of 515,000 and another may have produced an estimate of 490,000. If we could take a lot of samples like this, and plot the estimates from each sample, we would produce a chart of the sampling distribution of our estimate. Assuming that the estimation method we use to produce the estimate for each sample is unbiased, the shape of the plot would follow the widely recognised normal distribution, where the most likely estimates of the true value are centred towards the middle and the least likely estimates are at the “tail ends”.

In practice, in order to estimate the true value for a specific population of, say, the number of immigrants, we take one sample and produce a single estimate. We assume that the sampling distribution of our estimate would follow approximately a normal distribution, centred on the true value and we can use a statistical formula to calculate the standard error around the estimate. This is a measure of the accuracy of the estimate.

Of the estimates, 95% would lie within 1.96 multiplied by the true standard deviation of the sampling distribution. This also works the other way round, so we can say that for 95% of random samples taken, our estimate will be no more than 1.96 multiplied by the standard error of that estimate away from the true value that we are trying to estimate. Using this knowledge, we can calculate a confidence interval around our estimate.

Confidence intervals are indicators of the extent to which the estimate may differ from the true value. The larger the confidence interval, the less precise is the estimate. The central value within the confidence interval is the best estimate of the true value. The confidence interval around the estimate captures the uncertainty of the estimate and gives an interval within which we can say that there is a high probability that the true value lies.

At the 95% confidence level, which is a widely accepted level, we would expect the confidence interval to contain the true value 95 times out of 100. Equivalently, we can say that there would be a 1 in 20 chance that the true value would lie outside of the range of the 95% confidence interval.

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11. What is a statistically significant change?

Changes in the estimates from the International Passenger Survey (IPS) from one period to the next may occur simply by chance. In other words, the change may be due to which individuals were selected to answer the survey, and may not represent any real-world change in migration.

We are able to measure whether this is likely to be the case using standard statistical tests. These tests examine the difference between two estimates and calculate a confidence interval of the difference. The usual standard is to carry out these tests at the 5% level of “statistical significance”. When we report on statistical significance, we provide an assessment of how likely it is that we would see results as unusual as these if the true value of the population remained unchanged. The phrase "statistically significant at the 5% level" indicates that, if the true value of the population remained unchanged, a result like this would occur less than 5% of the time.

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12. What about the reliability of LTIM estimates?

Long-Term International Migration (LTIM) estimates are calculated from International Passenger Survey (IPS) estimates with additional data to account for flows of asylum seekers (including non-asylum enforced removals), flows between the Republic of Ireland and Northern Ireland and visitor and migrant switchers.

LTIM estimates are shown with the confidence intervals for the IPS component of the estimate in order to give you an indication of the accuracy of the estimate. The uncertainty associated with the IPS component of the estimate is used to calculate statistically significant changes in the LTIM estimates. However, when interpreting these confidence intervals and statistically significant changes, you should be aware that there is no method for quantifying the error associated with the non-survey components of LTIM, which are unlikely to be random.

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13. Glossary

Annual Population Survey (APS)

The Annual Population Survey (APS) is a continuous household survey, covering the UK, with the aim of providing estimates between censuses of main social and labour market variables at a local area level. The APS is not a stand-alone survey, but uses data combined from two waves from the main Labour Force Survey (LFS) with additional data collected on a local sample boost. Apart from employment and unemployment, the topics covered in the survey include housing, ethnicity, religion, health and education.

There are some differences between the APS and the 2011 Census. It should be noted that the APS:

  • excludes students in halls who do not have a UK resident parent

  • excludes people in most other types of communal establishments (for example, hotels, boarding houses, hostels, mobile home sites)

The 2011 Census included all usual residents in England and Wales.

The APS is a sample survey of households. There are approximately 320,000 persons per dataset.

The 2011 Census data refers to a point in time (27 March 2011), whereas the APS dataset relates to a period of 1 year (January to December).

British citizenship

The countries for which the migrant is a British passport holder can include the United Kingdom and the crown dependencies of Jersey, Guernsey and the Isle of Man and 12 British territories: Anguilla, Bermuda, British Indian Ocean Territory, British Virgin Islands, Caiman Islands, Falkland Islands/British Antarctic, Gibraltar, Montserrat, Pitcairn Islands, South Georgia and South Sandwich Islands, St Helena/Ascension, Tristan da Cunha, Turks and Caicos Islands. British Overseas is also a citizenship.

Citizenship

This is the term used in the International Passenger Survey (IPS) to define the country for which a migrant is a passport holder. This refers specifically to the passport being used to enter or leave the UK at the time of interview. It does not refer to any other passport(s) which migrants of multiple nationalities may hold. More generally a British citizen as described in IPS statistics includes those with UK nationality usually through a connection with the UK: birth, adoption, descent, registration, or naturalisation. British nationals have the right of abode in the UK.

Commonwealth (ONS statistical grouping)

The Commonwealth statistical grouping consists of countries of the Old Commonwealth and the New Commonwealth (see the relevant sections).

Confidence interval

This is the range within which the true value of a population parameter lies with known probability. For example, the 95% confidence interval represents the range in which, over many repeats of the sample under the same conditions, we would expect to find the true value 95 times out of 100. Equivalently, we can say that there would be a 1 in 20 chance that the true value would lie outside of the range of the 95% confidence interval. The uppermost and lowermost values of the confidence interval are termed “confidence limits”.

Country of birth

The country in which a person was born.

Country of usual residence

Based on the UN definition, the country in which a person has a place to live, where he or she normally spends the daily period of rest. Temporary travel abroad for purposes of recreation, holiday, visits to friends and relatives, business, medical treatment or religious pilgrimages does not change a person’s country of usual residence.

European Economic Area (EEA)

The EEA consists of the 28 countries of the EU (see the EU definition), plus Iceland, Liechtenstein and Norway. Swiss nationals are treated as EEA nationals for immigration purposes; however, for statistical purposes Switzerland is not included in EEA estimates by ONS.

European Union (EU)

European Union (EU) accession countries

The accession countries are those that joined the EU in 2004 or later. A total of 10 joined in 2004 (the EU8, plus Cyprus and Malta), two joined in 2007 (the EU2) and Croatia joined in 2013.

Between 2007 and 2013, EU2 nationals had certain restrictions placed on them; in the first 12 months of stay, working Bulgarian and Romanian nationals were generally required to hold an accession worker card or apply for one of two lower-skilled quota schemes. Other Bulgarian and Romanian nationals could apply for a registration certificate, giving proof of a right to live in the UK. These restrictions were lifted on 1 January 2014.

EU8 nationals previously had restrictions on their rights to work and were required to register under the worker registration scheme, but these restrictions were lifted from 1 May 2011.

EU14 and EU15

The Population by country of birth and nationality report refers to the EU14. The EU14 includes the countries of the EU, other than the UK, as constituted between 1 January 1995 and 1 May 2004 (that is, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Italy, Luxembourg, Netherlands, Portugal, Republic of Ireland, Spain and Sweden).

Other migration statistics refer to the EU15, which is the EU14 as well as the UK. However, although the UK is in the “EU15”, the EU15 statistics exclude British citizens (who are reported separately).

EU27

The EU27 (referred to in the Population by country of birth and nationality report) consists of the countries in the EU14, EU8 and EU2, plus Cyprus, Malta and Croatia. When including the UK in this group it becomes the EU28, but estimates for UK-born people are nevertheless provided separately.

Between 2004 and 2006, the grouping was known as the EU24 (that is, the EU14, EU8, Cyprus and Malta). On 1 January 2007, Bulgaria and Romania joined the EU making the grouping the EU26, and from 1 July 2013 Croatia was included making it the EU27.

International Passenger Survey (IPS)

The International Passenger Survey (IPS) is a survey of a random sample of passengers entering and leaving the UK by air, sea or the Channel Tunnel. Between 700,000 and 800,000 people are interviewed on the IPS each year. Of those interviewed, approximately 4,000 people each year are identified as long-term international migrants.

Intra-company transfer visa - short-term staff

This visa is for transfers up to and including 12 months into a role that cannot be filled by a new UK recruit. Applicants need to have worked for an employer overseas for at least 12 months.

Long-term international migrant

We 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.”

This is the definition used to calculate net migration and is also used for the UK usually resident population estimate series. This definition does not necessarily coincide with those used by other organisations.

Long-Term International Migration (LTIM)

Long-Term International Migration (LTIM) estimates are produced by combining migration data from the International Passenger Survey, Home Office data on asylum seekers (including non-asylum enforced removals adjustment), migration to and from Northern Ireland (from the Northern Ireland Statistics and Research Agency) and adjustments for visitor switchers and migrant switchers. From October 2015, data on people resettled in the UK under the various government resettlement schemes (such as the Syrian Vulnerable Persons Resettlement Scheme) have also been used to adjust the data, and have been published in LTIM estimates from May 2016 onwards.

National Insurance number (NINo)

National Insurance numbers are issued to non-UK nationals immigrating for work. The number of NINos will include people who are coming to the UK for short periods or temporary purposes, as well as long-term migrants. The figures are based on recorded registration date on the National Insurance recording and Pay As You Earn system (NPS), that is, after the NINo application process has been completed and so are not a direct measure of when a person migrated to the UK.

Nationality

Nationality is often used interchangeably with citizenship, and some datasets refer to “nationals” of a country rather than “citizens”. Different datasets have different ways of establishing someone’s nationality. The Annual Population Survey, which underlies the population estimates by nationality, simply asks people “what is your nationality”. However, the International Passenger Survey, National Insurance number and entry clearance visa data are based on people’s passports. For asylum statistics the nationality is as stated on the “Case Information Database”. This will usually be based on documentary evidence, but sometimes asylum seekers arrive in the UK without any such documentation.

New Commonwealth (ONS statistical grouping)

The New Commonwealth statistical grouping consists of African Commonwealth countries (Botswana, Cameroon, The Gambia, Ghana, Kenya, Lesotho, Malawi, Mauritius, Mozambique, Namibia, Nigeria, Seychelles, Sierra Leone, Swaziland, Tanzania, Uganda, Zambia and Zimbabwe), Indian subcontinent countries (Bangladesh, India, Pakistan and Sri Lanka), and other Commonwealth countries in the Asian, Caribbean, and Oceanian regions.

It also includes British Overseas Territories. Up to and including 2003, Malta and Cyprus are included in the New Commonwealth grouping. From 2004, the year of accession, they are included in the EU. Malta and Cyprus are members of both the Commonwealth and the EU from May 2004 onwards. However, for estimation purposes they have only been included in the EU grouping for 2004 onwards.

Rwanda was admitted to the Commonwealth in November 2009, but the definition for this statistical grouping has remained unchanged. Zimbabwe and The Gambia withdrew from the Commonwealth in 2003 and 2013 respectively, but again the definition for this grouping has remained unchanged.

New country groupings

We introduced new country groupings in 2014, which are now our current groupings. These are available for both Long-Term International Migration and International Passenger Survey estimates. A listing of which countries are in each of the current and old groupings is available.

Non-visa nationals

Non-visa nationals are people who do not require a visa to enter the UK. European Economic Area (EEA) nationals do not normally require a visa to enter the UK (although a small number of EEA nationals do apply and are issued visas). Additionally, for those non-EEA nationals classified as “non-visa nationals” (for example, citizens of the USA, Brazil and Japan) a visa is not normally required for visits of less than 6 months.

There are two ways in which non-visa nationals can enter the UK for work and study purposes without a visa. Non-visa nationals are allowed to work in the UK without a visa, but only for sporting or creative work of less than 3 months duration, this falling outside the scope of the UN definition of a short-term migrant. For study, there are many more admitted into the UK under the short-term study visa scheme than visas issued, as non-visa nationals are allowed to study under the scheme for up to 6 months without a requirement for a visa.

Old Commonwealth (ONS statistical grouping)

The Old Commonwealth statistical grouping consists of four countries: Australia, Canada, New Zealand and South Africa.

Other Europe

The country group Other Europe includes all those countries that are not members of the EU but are part of Europe. This includes members of the European Economic Area (see the relevant section), plus countries such as Albania, Turkey, and Ukraine.

Points Based System (PBS)

The PBS is a rationalisation of immigration control processes for people coming into the UK for the purposes of work or study who are not European Economic Area or Swiss nationals. Entries are classed into five tiers:

  • Tier 1 is for high value individuals such as investors and entrepreneurs
  • Tier 2 is for skilled workers with a job offer
  • Tier 3 is low skilled workers – this entry route was never opened and is currently suspended
  • Tier 4 is for students
  • Tier 5 is for youth mobility and temporary workers

In short-term migration outputs, data shown for “study” includes visas issued under Tiers 4 (implemented in March 2009) and pre-PBS equivalents.

Short-term student category (formerly known as “student visitors”)

The short-term student category (formerly known as “student visitors”) provides for those people who wish to come to the UK as a visitor and undertake a short period of study, which will be completed within the period of their leave (maximum 6 months unless applying under the concession for English language courses – 11 months). Short-term students (that is, those studying on courses of 6 months’ duration or less) who do not intend to work part-time or undertake a paid or unpaid work placement as part of their course can also apply within this category.

Short-term study

The short-term study provisions allow for individuals to come to the UK to undertake short courses or periods of no more than 6 months at a specified type of educational institution. Unlike Tier 4 this study can be at any level and does not have to lead to a qualification. In addition to the 6 month route, there is a concession for those studying English language courses longer than 6 months in duration, which allows individuals to study on English language courses up to 11 months in duration. The intention of these provisions is to enable an individual to study up to the level required to qualify for Tier 4 of the Points Based System.

The term “regular study visa” is used to denote those visas issued through the main study visa system. Figures are also presented for the short-term study visa scheme. There is some overlap in duration between short-term study visas and regular study visas (for example, both could be granted for 6 months), where applicants have a choice as to which to choose (with there being generally more restrictions placed on short-term study visas).

Short-term visa

The UN definition of short-term migrants relates to those who change their country of usual residence for between three and 12 months for the purposes of work or study. In line with this UN definition, the analysis of visas presented here relates solely to those who have arrived in the UK for work or study on short-term visas.

A short-term visa is defined as being a visa of less than 12 months duration. It is important to recognise that visa duration does not necessarily represent the length of stay, as many individuals will depart prior to the expiry date. Individuals may also be granted extensions of stay. It is, therefore, not possible to determine whether a holder of a visa has actually stayed for 3 months or more.

Most short-term student visas are issued for a fixed 6 months duration, or in some limited conditions for 11 months (with no possibility of extension in either case); because visa duration does not necessarily represent the length of stay, it is not possible to make any inference as to whether an actual visit exceeded 3 months from the 6 months fixed visa duration. Similarly, short-term visas issued for work and for regular study are likely to reflect an individual’s initial planned length of stay, with the actual length of stay potentially being longer due to extensions for work placements or study courses.

The figures presented in the Short-Term International Migration report relate to visas issued for entry clearance to the UK and are not related to individual countries within the UK. The figures include dependants.

Statistical significance

The International Passenger Survey interviews a sample of passengers passing through ports within the UK. As with all sample surveys, the estimates produced from them are based upon one of a number of different samples that could have been drawn at that point in time. This means that there is a degree of variability around the estimates produced. This variability sometimes may present misleading changes in figures as a result of the random selection of those included in the sample. If a change or a difference between estimates is described as “statistically significant”, it means that statistical tests have been carried out to reject the possibility that the change has occurred by chance. Therefore statistically significant changes are very likely to reflect real changes in migration patterns.

Study

Estimates for study refer only to migrants arriving to or leaving the UK for formal study.

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14. List of products

The following links provide information and additional detail associated with our migration statistics releases. All are Office for National Statistics (ONS) products unless otherwise indicated.

Main annual releases

Migration Statistics Quarterly Report (MSQR) - a summary of the latest official long-term international migration statistics published by ONS, the Home Office and the Department for Work and Pensions (DWP). Latest version: 24 August 2017.

Final Long-Term International Migration (LTIM) estimates - a compendium of tables containing the latest final estimates of long-term international migration. Latest version: 1 December 2016.

Short-Term International Migration (STIM) Annual Report - a report and tables detailing estimates of short-term international migration to and from England and Wales. Latest version: 25 May 2017.

Local Area Migration Indicators Suite - an interactive product bringing together different migration-related data sources to allow you to compare indicators of migration at local authority level. Latest version: 24 August 2017.

Population of the UK by country of birth and nationality - a short report focusing on changes in the UK resident population by country of birth and nationality. Latest version: 24 August 2017.

International Migration Timeline - an interactive chart exploring the longer-term picture of international migration to and from the UK from 1964 until the most recent published annual data. Latest version: 1 December 2016.

LTIM and MSQR - guidance and methodology

Table of Contents – provides links to all of the international migration tables.

Long-Term International Migration – frequently asked questions and background notes - information on recent trends in migration, methods and coverage, comparisons with international migration estimates, a complete list of definitions and terms and a guide to the published tables.

MSQR Information for Users - an introduction to the main concepts underpinning migration statistics including basic information on definitions, methodology, use of confidence intervals and information on the range of available statistics related to migration.

International Migration Statistics first time user guide, glossary and list of products - guidance on interpreting confidence intervals, the difference between provisional and final estimates and the comparability and quality of input data sources.

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

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

Long-Term International Migration estimates methodology - a detailed methodology document for LTIM estimates, including information on current methodology and assumptions, data sources including the International Passenger Survey and changes to the methodology since 1991.

International Passenger Survey: quality information in relation to migration flowss - an overview of the quality and reliability of the International Passenger Survey in relation to producing Long-Term International Migration estimates.

Quality of Long-Term International Migration Estimates from 2001 to 2011

Guidance on revised net migration statistics - information on how to interpret the revised net migration estimates for 2001 to 2011 alongside published LTIM estimates.

LTIM and MSQR – articles

Note on the differences between Long-Term International Migration flows derived from the International Passenger Survey, and estimates of the population obtained from the Annual Population Survey - a summary of the differences between LTIM flows estimates and the stocks data provided by the APS, highlighting why the year-on-year change in the APS should not be used as a proxy for a measure of international migration flow.

What are migration levels like in your area? – includes a quiz.

Overview of population statistics - describes different aspects of the population we measure and why, including a section focusing on the impact of migration on the population.

Note on the difference between National Insurance number registrations and the estimate of long-term international migration: 2016 – in-depth research into the differences between NINos and the IPS.

Sources of Migration Statistics - a summary of the differences between NINos and the IPS.

A comparison of international estimates of long-term migration

International student migration – what do the statistics tell us - information on the differences between various migration data sources. Updates to this article were published November 2016, April 2017 and August 2017 to better understand student migration to and from the UK.

Seasonal Patterns of Long-Term International Migration

Emigration – A Short Story

Report on the history of immigration to the UK based on the 2011 Census -published in December 2013, in collaboration with the Home Office, which provides further analysis on the drivers of historical migration to England and Wales.

The reason for migration and labour market characteristics of UK residents born abroad (September 2014) - uses data from the Labour Force Survey to provide estimates of the stock of residents born abroad by the reason for original migration. This report revealed that the distribution of original reasons given by non UK-born residents of the UK was very different from that produced when looking at the migration flows reported in the IPS.

Travel Trends, 2016 - includes estimates of travel and tourism to and from the UK.

International migration and the changing nature of housing in England – what does the available evidence show? - This article provides information about international migration, population change and changes in housing trends in England.

International immigration and the labour market, UK: 2016 – looks at the labour market characteristics of UK, EU and non-EU nationals in the UK labour market.

Comparing sources of international migration statistics: December 2016 – outlines the differences between migration data sources and points to more detailed papers regarding this.

International migration data and analysis: Improving the evidence - Future development plans for improving our data sources.

What information is there on British migrants living in Europe? January 2017 - explores statistics available to estimate the number of British migrants living in Europe.

Migration, the European Union and work: How much do you really know? – released in July 2017 by Visual.ONS, this interactive article provides topical information on the characteristics of migrants from the various EU country groupings who arrive in the UK to work.

Short-Term International Migration - accompanying documents

Short-Term International Migration – frequently asked questions

Short-Term International Migration methodology – national estimates

Short-Term International Migration methodology – local authority estimates

Quality and Methodology Information for Short-Term International Migration Estimates for England and Wales

Quality and Methodology Information for Short-Term International Migration Estimates for Local Authorities

2011 Census, Short-term Residents for Local Authorities in England and Wales

Examining the differences between the mid-year Short-term Immigration Estimates and the 2011 Census for England and Wales

Population of the UK by country of birth and nationality - accompanying documents

Population of the UK by country of birth and nationality asked questions

Population of the UK by country of birth and nationality Quality and Methodology Information

Population of the UK by country of birth and nationality, reweighted data for calendar year 2004 to 2013 - publication of revised datasets following the reweighting of the Annual Population Survey in light of results of the 2011 Census. The product was published in July 2015 as a one-off publication.

The effect of reweighting on the Annual Population Survey estimates of the UK population by country of birth and nationality

2011 Census provides information on the population of England and Wales on Census Day, which was 27 March 2011. A number of articles relevant to migration have been published including Immigration Patterns of Non-UK Born Populations, Country of Birth and Nationality Analysis, Non-UK Born Short-Term Residents and International Migrants in England and Wales.

2011 Census data section

Publications by other teams

Labour Market Statistics - this includes estimates of the number of people in employment in the UK by country of birth and nationality.

Internal Migration, England and Wales YE June 2015 – looks at migration between local authorities and regions in England and Wales, as well as moves to or from the rest of the UK (Scotland and Northern Ireland).

Population estimates for UK, England and Wales, Scotland and Northern Ireland: mid-2015 – estimates of the usual resident population, which migration statistics feed into.

Home Office Research Report 68 (November 2012) - presents information from academic research and surveys drawn together to present the main aspects of long-term emigration from the UK. This includes recent outward migration and some trends over the last 20 years, separately for British, EU and non-EU citizens.

'Statistics on changes in migrants’ visa and leave status: 2015 (Home Office) – - (formerly known as ‘”The Migrant Journey”) research which shows how non-EEA migrants change their immigration status, and the immigration routes used prior to achieving settlement in the UK.

Immigration Statistics January to March 2017 (Home Office)

Immigration Statistics User Guide (Home Office)

Entry Clearance Visas by Length (Home Office) - Home Office analysis on the length of entry clearance visas issued outside the UK.

National Insurance number (NINo) allocations to adult overseas nationals (DWP)

National Records for Scotland migration statistics provide estimates of migration within Scotland, between Scotland and the rest of the UK and between Scotland and overseas.

Northern Ireland Statistics and Research Agency migration statistics provide estimates of long-term international migration to and from Northern Ireland, including by local government district.

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Contact details for this Methodology

Nicola White
migstatsunit@ons.gsi.gov.uk
Telephone: +44 (0)1329 444097