The Office for National Statistics (ONS) uses data from the International Passenger Survey (IPS), Labour Force Survey (LFS) and Home Office data on asylum seeker flows and their dependants and non-asylum enforced removals, in order to produce estimates of Long-Term International Migration (LTIM).
The Home Office, who are responsible for immigration control and applications for settlement, citizenship and asylum, provide ONS with data on principal applicant asylum seekers and their dependants. Data are provided for different types of asylum seekers. These include the number of people who:
- applied for asylum
- were refused asylum
- appealed against their asylum decision
- were returned home
- withdrew their asylum request
These different categories dictate whether the asylum seeker is leaving or entering the UK.
An adjustment for asylum seekers returned, departing voluntarily, or withdrawing their application and leaving the UK within a year of the application, is made. This, therefore, excludes those who are not long-term migrants from the LTIM estimates. Asylum applications covered by the Home Office can be identified as either port or in-country. Port asylum seekers (the minority) are those who apply at port when entering the UK. Most port asylum seekers are not captured in the IPS. An allowance is made when estimating port asylum seekers for the small number of migrants in the IPS data who give seeking asylum as their reason for entry and will, therefore, be double-counted if kept in. In-country asylum seekers are those who enter the UK and later apply for asylum while in the UK. It is assumed that information about planned duration of stay given to the IPS interviewer is the same as that given to the Immigration Officer and, therefore, that in-country asylum seekers are unlikely to be captured as migrants in the IPS. In summary, asylum seeker immigration figures are based on the number of people applying for asylum.
These data are used to adjust the IPS estimates in order to:
- exclude those asylum seekers counted by the IPS on arrival in the UK to remove the possibility of double-counting
- allow for the small numbers of those counted in both the principal applicant and dependant applications data
- exclude those who were returned within a year of their application
This report covers 8 administrative data sources:
- Asylum seekers – left the UK prior to conclusion
- Asylum seekers – refusals
- Asylum seekers – appeals allowed
- Asylum seekers – withdrawals
- Asylum seekers – within-a-year removals
- Asylum seekers – applications
- Asylum seekers – removals
- Non-asylum enforced removals
This report covers the processes, from data collection through to publications produced by the Population Statistics Division (PSD) of the Office for National Statistics (ONS) and focuses on quality assurance. It identifies potential risks in data quality and accuracy as well as details of how those risks are mitigated.
This report is intended to supplement existing documentation:
- Long-Term International Migration Quality and Methodology Information
- Migration Statistics Quarterly Report – Information for Users
- Long-Term International Migration estimates methodology
- User Guide to Home Office Immigration Statistics
This report has been published in a bid to help you understand data processing and provide reassurance that the subsequent statistics, produced by PSD using asylum seeker data and non-asylum enforced removals data, are suitably robust.
Within PSD, the Migration Statistics Unit (MSU) uses these data to calculate LTIM estimates for each quarter. Provisional estimates are published every quarter within the Migration Statistics Quarterly Report (MSQR). Final estimates are published for the previous calendar year in the November MSQR.
Within PSD, the 7 asylum seeker data sources and non-asylum enforced removals data were assessed using the UK Statistics Authority’s Quality Assurance of Administrative Data Toolkit.
Data on asylum support have also been assessed in a separate QAAD report, covering the assurance level and supporting evidence.
The result of the assessment for the non-asylum enforced removals data is an A1 rating, which means that a basic level of assurance is required. The assessment for the 7 asylum seeker data sources has resulted in an A2 rating, which means that an enhanced level of assurance is required. This report will provide information to meet these levels of assurance. If you feel that this report does not adequately provide this assurance then please contact firstname.lastname@example.org with your concerns.
The toolkit outlines 4 areas for assurance; the rest of this report will be split into these areas, with further subdivisions by country. The areas for assurance are:
- operational context and administrative data collection
- communication with data supply partners
- quality assurance principles, standards and checks applied by data suppliers
- producer’s quality assurance investigations and documentation
2.1 Asylum seeker data
Asylum is protection given by a country to someone who is fleeing persecution in their own country. It is given under the 1951 United Nations Convention relating to the Status of Refugees. The Convention defines a refugee as a person who, “owing to a well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality and unable or, owing to such fear, is unwilling to avail himself of the protection of that country; or who, not having a nationality and being outside the country of his former habitual residence, as a result of such events, is unable or, owing to such fear, is unwilling to return to it.”
The criteria for recognition as a refugee and hence the granting of asylum, are set out in the 1951 United Nations Convention relating to the Status of Refugees, extended in its application by the 1967 Protocol relating to the Status of Refugees. The 1951 Convention is given effect in British law by references in the Nationality, Immigration and Asylum Act 2002, the Asylum and Immigration Appeals Act 1993, the Refugee and Person in Need of International Protection (Qualification) Regulations 2006 and the Immigration Rules.
Under paragraph 334 of the Immigration Rules, an asylum applicant will be granted asylum in the UK if the Secretary of State is satisfied that:
- they are in the UK or have arrived at a port of entry in the UK
- they are a refugee, as defined in regulation 2 of the Refugee or Person in Need of International Protection (Qualification) Regulations 2006
- there are no reasonable grounds for regarding them as a danger to the security of the UK
- they do not, having been convicted by a final judgment of a particularly serious crime, constitute danger to the community of the UK
- refusing their application would result in them being required to go (whether immediately or after the time limited by any existing leave to enter or remain), in breach of the Geneva Convention, to a country in which their life or freedom would be threatened on account of their race, religion, nationality, political opinion or membership of a particular social group
A person must apply for asylum if they want to stay in the UK as a refugee. They should apply when they arrive in the UK or as soon as they think it would be unsafe for them to return to their own country. Dependants may be included as part of the asylum application. An application which does not meet the criteria will be refused.
After a person applies for asylum, they will have a meeting with an immigration officer (called a screening). They register their asylum claim with the immigration officer. The screening may be at the border or in the UK. They will then have an asylum interview with a case worker. After the asylum interview, a case worker will make a decision on the application. A decision will usually be made on an application within 6 months.
Possible outcomes are:
- grant of asylum as a refugee
- grant of Humanitarian Protection
- grant of other leave
- refusal of asylum application
- the application is withdrawn
Data relating to the processing of asylum applications are extracted from the Home Office’s Case Information Database (CID).The figures for applications only relate to the initial application for asylum. Case workers input information relating to cases onto the database. Identification documents required by applicants include:
- passport and travel documents
- police registration certificate
- national identity card
- birth certificate
Proof of address is also required if the applicant is in the UK.
Asylum applicants have the right to appeal a decision, provided they are eligible. The HM Courts and Tribunals Service (HMCTS) (formerly Tribunals Service Immigration and Asylum and the Asylum and Immigration Tribunal (AIT)), an executive agency of the Ministry of Justice, hears and decides appeals against decisions made by the Home Office. It consists of the First-tier Tribunal Immigration and Asylum Chamber and Upper Tribunal Immigration and Asylum Chamber. The First-tier Tribunal Judge will decide whether the appeal against the decision is successful or not; this is known as the decision being allowed or dismissed.
2.2 Non-asylum enforced removals
The Home Office also collects data on non-asylum enforced removals, which occur where it has been established that a person has breached UK immigration laws and/or has no valid leave to remain in the UK, given they have applied for asylum at any point in the past. The person has declined to leave voluntarily and the Home Office enforces their removal from the UK. They would not be counted in the IPS when leaving the UK. No adjustment for these people is required for inflow estimates, as they were not asylum seekers and therefore would be counted in the IPS on entering the UK. Figures for non-asylum enforced removals are also extracted from CID.
Cases have been linked with visa data to only include those who held a visa of 12 months or more.Back to table of contents
The provision of Home Office data to the Office for National Statistics (ONS) on asylum seekers and their dependants and non-asylum enforced removals data is covered by a memorandum of understanding between the Home Office and ONS.
The agreement covers:
- issue resolution
- Memorandum of Understanding management arrangements
- data to be delivered and data management
- data delivery method and security
- standards, quality and performance
The data covered by the Memorandum of Understanding are:
- applications – people who have applied for asylum in the UK; these only relate to the initial application for asylum
- withdrawals – people who have withdrawn their asylum application
- withdrawals known to have left the UK – people who have withdrawn their asylum application and are known to have left the UK
- appeals allowed – people, whose application for asylum was refused, who appealed and who have been granted asylum, humanitarian protection or discretionary leave to remain
- refusals – people, who have been refused asylum, humanitarian protection or discretionary leave to remain
- removals – people, who have been refused asylum, humanitarian protection or discretionary leave to remain and, who, have either been forcibly removed or assisted in leaving or left as voluntary departures following enforcement action initiated against them
- within-a-year removals – a subset of removals, as defined above, who were removed within a year of their application
- non-asylum removals – those who are escorted directly to their removal transport without passing through the International Passenger Survey (IPS) sampling area, with visas of 12 months or more, at postcode level
The timetable for data supply is recorded in the Memorandum of Understanding. The provisional data are delivered in quarters 4 months after the end of the quarter of interest. Final data for the whole year are delivered 10 months after the end of the year.
The variables requested are:
- age (single years)
- number of cases
- principal applicant or dependant (for asylum seekers)
Quality assurance (QA) checks on the data are carried out by Migration Statistics Unit (MSU) for each quarter and are signed off by the Head of MSU as part of the Migration Statistics Quarterly Report prior to publication.
If there are any issues relating to the data, they are discussed and resolved with the Home Office. If a revision has to be made to the data, a new dataset will be supplied. Notes of any data issues are maintained in the QA check documentation, which are stored on MSU systems.
Quarterly meetings are held with the Home Office to discuss data quality issues that have arisen or that may arise. Data will be delivered via a secure data transfer method and stored on a restricted access server.
3.1 Engagement with users
Population Statistics Division (PSD) continually engages with users, through a variety of means, to understand how our outputs are meeting their requirements. Feedback provided tends to relate to the overall statistical methodology and the impact on the final statistics, rather than to any individual data source. To date no specific feedback on the use of these data sources have been provided.Back to table of contents
4.1 Asylum seekers data
Asylum seekers data are:
- administrative counts of casework processes, which are defined in UK legislation and are recorded under detailed categories on the Home Office’s administrative databases
- have not, in recent years, had to be altered significantly between initial provisional totals released in February each year and subsequent revised totals released in the following August
The Home Office reconciles the asylum applications, initial decisions and withdrawals, data for main applicants with teams within the Home Office, by ensuring that the total number of records produced separately by the Home Office is within 2% of the data extracted by the Home Office Migration Statistics team. If the total is not within 2%, then analysis of the individual records are made. A 2% level of tolerance has been chosen between the datasets due to the system being live, rather than snapshot: as such the data are prone to change between extracts taken close together.
The Home Office reconciles data on the non-suspensive appeals process, with a team within the Home Office, by comparing a unique identifier from each case in the Home Office Migration Team’s extract against record level data provided by the Home Office. When an individual is found within only 1 of the extracts, detailed data quality checks are carried out to ascertain whether the case should be counted.
Data are checked for consistency against previous totals and significant changes are investigated by the Home Office.
The level of missing data on related fields such as sex and nationality is very low. The following are known data quality issues which affect a small number of cases:
- incomplete date of birth
- incorrect outcome selected, for example, exceptional leave to remain (after 1 April 2003), humanitarian protection and discretionary leave (before 1 April 2003)
- case created on the CID before the date of application
The data quality for the total numbers of asylum applications and initial decisions is considered to be high. In addition to the above, these data:
- undergo a reconciliation process
- are scrutinised closely as part of the performance monitoring of the Home Office, where a wide range of checks are implemented, such as comparing figures with previous quarters
- are assessed as part of the Home Office’s Statement of Compliance with the Code of Practice for Official Statistics; with QA relating to both the data itself and the operations behind it
The number of asylum applications and decisions relating to dependants are subject to a slightly larger percentage increase than those relating to main applicants between the data published each quarter and the revised data published each August. This increase is expected and is not considered to be a data quality issue, as the count of dependants includes those who are born or join the main applicant after the asylum application is made, with the dependant being counted in the same quarter that the original asylum claim was recorded.
Data quality on asylum appeals is considered to be high and is tracked against similar data from Ministry of Justice.
4.2 Non-asylum enforced removals data
The statistics on returns are extracted from the Case Information Database (CID). The data are derived from administrative information used for the processing of cases which are subject to removal action.
Overall, the data quality for the total numbers of those returned is considered to be high.
- are administrative counts of the Home Office’s casework processes, which are defined in UK legislation and are recorded under detailed categories on the Home Office’s administrative database1
- are scrutinised closely as part of the performance monitoring of the Home Office1
- are regularly assessed as part of the Home Office’s Quality Assurance Framework
- undergo a detailed reconciliation process
- are subject to internal data quality checks
The level of missing data on related fields such as sex and nationality is very low. The following are known data quality issues which affect a small number of cases.
- in some cases, there is insufficient evidence on the database to confirm that a return took place, in which case it will not be counted
- figures for those aged under 14, 14 to 15, 15 to 16 and 16 to 17 may have over-coverage because some applicants aged 18 or over may claim to be younger on their date of departure
Notes for: Quality assurance principles, standards and checks applied by data suppliers
- This relates to total removals, of which non-asylum and asylum are subsets; this is not in relation to removals which are escorted or removed from detention.
The data for the 7 asylum seeker data sources include information on principal applicants and dependants. A bespoke system is used to process the data relating to Long-Term International Migration (LTIM), which utilises the different data sources to calculate asylum seeker inflows and outflows for each migrant characteristic (country of birth, country of last or next residence, intended length of stay, marital status, occupation prior to migration) for the LTIM tables. In this system, a number of high-level assumptions are made. These include that:
- for inflows all asylum seekers are long-term immigrants
- for outflows asylum refusals will become emigrants a year after their application is refused
- for every asylum seeker country of birth and country of last or next residence is assumed to be the country of their citizenship
The non-asylum enforced removals are delivered as a separate dataset by the Home Office and are also processed in the bespoke system. The data does not include an assessment as to the number of those who were principal applicants and those who were dependants. Non-asylum enforced removals are assumed to be long-term emigrants. The data are appended to the data for principal applicant asylum seekers who are removed more than a year after they arrived in the UK. The outputs from the bespoke system are fed into the LTIM report.
For the asylum seeker data, Migration Statistics Unit (MSU) produce a quality assurance spreadsheet that looks at quarter-on-quarter and year-on-year changes to check there have been no major changes when assessing the time series. They then compare the data sent to them by the Home Office against what has been published on their website, to make sure it matches. Checks on citizenship to look at patterns for different countries and regions are carried out. Plausibility checks are also undertaken to see whether the data appear to be credible. Checks are made on age: those aged under 1 are removed; those with an age of 98 or over are looked at. Once the data have been processed through the bespoke system, MSU then do further checks to make sure the outputs from the bespoke system are consistent, quarter-on-quarter and year-on-year and then explore certain groups (for example, asylum seekers from a particular country or region) to see if there has been a large increase in numbers of asylum seekers within these groups.
For the non-asylum enforced removals, MSU check that it is internally consistent (that is, the sum of the individual rows matches the totals) and then compare the most recent data with previous data supplies.
Asylum seeker data and non-asylum enforced removal data are included in the estimation of migration estimates, as they are not generally captured by the International Passenger Survey (IPS).Back to table of contents
6.1 Strengths and limitations
The main strengths and limitations of the data are:
- the asylum seekers covers a known gap in coverage of the International Passenger Survey when looking to calculate Long-Term International Migration
- they offer complete coverage of that group
- they are extracted from a live system so are subject to change when more than 1 extract is required
- they are subject to change over time as more dependants can be added to an application due to births or other family members joining the original applicant at a later date
6.2 Level of assurance
Migration Statistics Unit (MSU) deem that the non-asylum enforced removals data have a low risk of quality concerns due to the alignment between the purpose for collection and the use in statistical production, the standardised collection process and the quality of the data provided.
MSU deem that the onward use of the data, in migration statistics, have a higher public-interest profile due to the high levels of policy and media interest in this area.
As such, non-asylum enforced removals are deemed by MSU to have an A1 rating: basic assurance.
MSU deem that the asylum seeker data have a low risk of quality concerns due to the alignment between the purpose for collection and the use in statistical production, the standardised collection process and the quality of the data provided.
MSU deem that the onward use of the data, in migration statistics, have a higher public-interest profile due to the high levels of policy and media interest in this area.
That said, the asylum seeker data are subject to a relatively high volume of quality assurance checks within the Office for National Statistics (which rarely yield issues) and as such asylum seeker data are deemed by MSU to have an A2 rating: enhanced assurance.Back to table of contents
Contact details for this Methodology
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