Accessing NILS

We welcome requests from all researchers to access NILS data and we have a research support unit to assist at all stages of the application process. NILS data can be accessed, on a project basis, within a secure setting in Colby House, Belfast.

All researchers wishing to gain access to NILS (and NIMS) data must

All proposals must meet the following criteria:

(1) have a longitudinal aspect

(2) illustrate how using NILS/NIMS data will uniquely contribute to the study

(3) provide clear evidence of the value of their proposed study to Health and Social Care-related research and specific policies (please note that this is based on the World Health Organization’s ‘social determinants of health’ model which broadly defines health as a state of complete physical, mental and social well-being)

(4) support the development/delivery of public policy

 

If you are unsure whether your project meets all criteria, please contact us to discuss your idea further before beginning an application.

A visual overview of the NILS application process can be viewed here. We would advise making contact with the RSU team at the earliest opportunity to discuss your idea and a realistic timeframe. We would recommend sending a brief summary and outline of your project (max 1 page) to ensure it meets approval criteria and will be feasible using the NILS sample.

The full project application form will consist of an outline of the rationale for your project and a list of variables you will require to carry out your analysis. If your project requires linking data from a source outside of NILS core datasets, (i.e. a Distinct Linkage Project or DLP), NILS Research Support Unit will begin discussions with the relevant data custodians. Your completed project application form will then be submitted to the Approvals Panel.

The NILS Research Approvals Group meet every two months to consider applications for approval. They assess whether projects should be approved and may provide advice on how projects could be improved or stipulate changes to be made: please refer to the NILS RAG Applications Criteria. Check out this video tutorial with tips and suggestions on how to write a successful NILS application.

The NILS RAG includes representatives from the Health and Social Care Research and Development Division of the Public Health Agency (HSC R&D Division), Health and Social Care Business Services Organisation, Department of Health, Social Services and Public Safety, NISRA and academia.

Researchers have the right to appeal any decisions in relation to their application. All decisions taken in relation to unsuccessful applications will be fully documented.

The NILS database has ethical approval from ORECNI. However, if the potential project intends to link health data to the NILS database, further ethical approval is required. This ethical approval must be applied for by the researcher team. Further information can be obtained through the ORECNI website.

Following the approval of your NILS project, the Research Support Unit will generate a project specific dataset. This will only be made available to project team members named on the application form and who have signed the licence agreements.

Once the accreditation process is complete, and the project has been approved, the researcher can be granted access to the Secure Environment. This is a strictly controlled setting governed by policies, protocols and procedures to ensure data confidentiality. Researchers within the secure environment are supervised at all times by NISRA RSU staff.

To book into the Secure Environment contact the RSU at rsu.nisra@gov.uk. Please bear in mind that the Secure Environment will be closed between 9am and 12pm on the first Thursday of every month for essential maintenance.

All members of the research team must be an accredited researcher. Details can be found on the NISRA website.

Available Data

You can check the full NILS Metadata for detailed descriptions of the NILS sample. You can also find full details of all the NILS/NIMS variables (including descriptions, field values and SPSS/STATA analysis code) in our Microsoft Access Data Dictionary

NILS Core Datasets

Table Name: CORENILSDATA

Table Description: NILS members’ core information based on Health Card Registrations. A person is chosen as a NILS member if the day and month of their date of birth falls on one of the 104 NILS dates. The NILS members are selected from the earliest available Health data download (April 2001) and identified as being ‘Live’ in at least one of the health downloads. To integrate the 1991 Census into NILS, NILS members born before April 1991 and who either died or emigrated between April 1991 and April 2001 were included. The full NILS metadata can be found here.

Data Source: Business Services Organisation (BSO) Health Card Registrations

Number of Records: 776666

Data Releases: Latest information included for April 2018. This table is updated and released every 6 months.

NIMS

Data Source: Northern Ireland Mortality Study (NIMS)

Data Description: The NIMS is a large-scale data linkage study that links the 1991, 2001 and 2011 Census returns for the whole of the enumerated population (approximately 1.6 million individuals) to subsequently registered mortality data from the General Register Office (GRO). While larger than NILS it is more limited in scope, focusing only on the linkage of mortality data. It allows researchers to focus on more detailed analyses of specific cause of death, some of which may not be possible in NILS because of small numbers in sub-populations and the analysis of less common causes of death (e.g. accidental death). The NIMS dataset is recommended to researchers whose primary interest is in mortality in Northern Ireland. These data are maintained under the same conditions as the NILS and is accessible only under the same constraints. The full metadata can be accessed here.

Census 1981

Table Name: CENSUSP_1981

Table Description: This table gives statistical coded person information from the 1981 Census for NILS members with a census link and non-NILS members living in a household with a NILS member. This table only includes the enumerated population. The Census 1981 linkage is based on WARD1984 boundaries and SOA2001_Old which is an approximation of SOA based on a 1km grid-square location. These levels of geography may not be directly comparable to those used within other Census linkages. A Summary Report which details key results of the 1981 Census can be found at: https://www.nisra.gov.uk/publications/1981-census-reports

Data Source: 1981 Census

Number of Records: 915482 (340033 NILS members and 575449 other household occupants)

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

 

Table Name: CENSUSHH_1981

Table Description: This table gives statistical coded household information from the 1981 census for all NILS members with a census link. This table only includes households within the enumerated population. The Census 1981 linkage is based on WARD1984 boundaries and SOA2001_Old which is an approximation of SOA based on a 1km grid-square location. These levels of geography may not be directly comparable to those used within other Census linkages. A Summary Report which details key results of the 1981 Census can be found at: https://www.nisra.gov.uk/publications/1981-census-reports

Data Source: 1981 Census

Number of Records: 227687

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

Census 1991

Table Name: CENSUSP_1991

Table Description: This table gives statistical coded person information from the 1991 Census for NILS members with a census link and non-NILS members living in a household with a NILS member. This table only includes the enumerated population.

Data Source: 1991 Census

Number of Records: 1088336 (439560 NILS members and 648776 other household occupants)

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

 

Table Name: CENSUSHH_1991

Table Description: This table gives statistical coded household information from the 1991 census for all NILS members with a census link. This table only includes households within the enumerated population.

Data Source: 1991 Census

Number of Records: 297281

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

Census 2001

Table Name: CENSUSP_2001

Table Description: This table gives statistical coded information from the 2001 census for NILS members with a census link and non-NILS members living in a household with a NILS member. This table only includes the enumerated population. It also includes some students identified as being away at term time. To filter these out users should use the STU_INDP0 and TTADDP0 fields.

Data Source: 2001 Census

Number of Records: 1066684 (457412 NILS members and 609272 other household occupants)

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

 

Table Name: CENSUSHH_2001

Table Description: This table gives statistical coded household information from the 2001 census for all NILS members with a census link. This table only includes households within the enumerated population.

Data Source: 2001 Census

Number of Records: 320741

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

Census 2011

Table Name: CENSUSP_2011

Table Description: This table gives statistical coded information from the 2011 census for NILS members with a census link and non- NILS members living in a household with a NILS member. This table only includes the enumerated population. It also includes some students identified as being away at term time. To filter these out users should use the STUDENTP1 and TERMINDP1 fields. People who are not identified as permanent residents of Northern Ireland can be excluded using the INTENTIONP1 field.

Data Source: 2011 Census

Number of Records: 1088832 (486682 NILS members and 602150 other household occupants)

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

 

Table Name: CENSUSHH_2011

Table Description: This table gives statistical coded household information from the 2011 census for all NILS members with a census link. This table only includes households with the enumerated population.

Data Source: 2011 Census

Number of Records: 354514

Data Releases: Typically static, but a small number of records may be added at each download due to additional matching exercises

Vital Events

Table Name: EVENTS

Table Description: This table gives the linking ID for all the vital event occurrences to a NILS member, or in the case of widowerhoods, their spouse. It currently includes 7 types of events relating to births, deaths, marriages and the introduction of widowerhoods within the JUN2016 download. It will potentially be expanded over time to also include stillbirths, infant deaths, etc. Each NILS member can have many events. Only those with a valid link are included. Those that were expected to be matched but where a match could not be found are excluded.

Data Source: General Register Office (GRO)

Number of Records: 1025635

Data Releases: At each new release of the GRO data more events will be included. There is a significant increase in the number of records from JUN2015 due to the addition of historical births information, from JAN2016 due to the addition of marriage information from 2005 onwards and from JUN2016 with the addition of widowerhood information from 1991 onwards.

Property

Table Name: PROPERTIES

Table Description: This table gives the coded information from Land and Property Services POINTER product and valuation lists, of which more information can be found at https://www.nidirect.gov.uk/articles/pointer. This table is based upon all properties listed in the latest available POINTER dataset linked to latest available LPS valuation list where possible.

Data Source: Land and Property Services (LPS)

Number of Records: 999834

Data Releases: Based on DECEMBER 2016 LPS Data & MARCH 2018 POINTER Data. At each new data release a number of records may be added.

Weather & Pollution

Table Name: WEATHER

Table Description: This table provides background weather data at 5×5 km resolution which is modelled by the Met Office every ten years. It is linked to the Pointer database based on the 5km grid square which has been translated from the British to Irish grid. Each household on the Pointer database is assigned a range of weather measures which can then be linked to other datasets via XUPRN. Further information on weather data is available at http://www.metoffice.gov.uk/climatechange/science/monitoring/ukcp09/download/

Data Source: Met Office

Number of Records: 999834

Data Releases: JANUARY 1981 to DECEMBER 2010. Average over thirty year period – 1981-2010. Updated every ten years. Last updated April 2012.

 

Table Name: POLLUTION

Table Description: This table provides background pollution data at 1×1 km resolution which is modelled by DEFRA on an annual basis. It is linked to the Pointer database based on the 1km grid square which has been translated from the British to Irish grid. Each household on the Pointer database is assigned a range of pollution measures which can then be linked to other datasets via XUPRN. Further information on pollution data is available at http://uk-air.defra.gov.uk/data/pcm-data

Data Source: DEFRA

Number of Records: 999834

Data Releases: JANUARY 2001 to DECEMBER 2016. Data updated annually.

School

Table Name: SCHOOL

Table Description: This table provides coded school level information which has been drawn from the annual school census exercise carried out by the Department of Education. It is linked to the 2011 Census which included data on travel to place of work or study and subsequently can be linked to the CENSUSP_2011 table using SCHOOL_ID. The information was coded/validated by the teams in DE and Census Office and more information on school enrolment data can be found at https://www.education-ni.gov.uk/articles/school-enrolments-school-level-data

Data Source: Department of Education (DE)

Number of Records: 1,120

Data Releases: School Enrolment data 2010/11. Data will remain static.

Area based characteristics

SOA Geography Methodology

Over time the various Northern Ireland Census’ have used different geographies and different methods of applying those geographies onto households within NI. To allow consistency of geographies over time for research purposes Super Output Areas have been deemed the most suitable. To allocate SOA for each Census the following methods have been used:

2001 Census – SOAs were created using the 2001 Census information

2011 Census – New SOAs were created as new houses had been built and land shifted. They will be very similar to those created in 2001.

1991 Census – Postcodes were collected. These were linked to the Central Postcode Directory in order to assign a 2001 SOA to the 1991 information.

1981 Census – No postcode information was collected, however 1km grid square data for homes was used and the closest 2001 SOA was assigned.

SETTLEMENTBAND

Each property lies within a recorded settlement band. These settlement bands enable researchers to determine whether a property is located within an urban or rural area. Settlement bands A-E reflect urban areas, whilst settlement bands F-H indicate rural areas. The following table shows distribution of properties by urban/rural classification.

Data Linkage Projects

The NILS and NIMS have received ethical approval for all research on migration, fertility, mortality and inequalities and can routinely link to the datasets outlined above. There is also the potential to link to other administrative datasets, such as health and social care, for specially defined one-off studies. These are subject to additional legal and ethical scrutiny and privacy protection protocols. Examples include cancer screening, prescribing and dental services data. For further information, please contact us to discuss.

Users Own

Researchers may wish to have external data attached to their extract, for example linking data to specific event dates. Researchers must clearly outline requirements they may have in relation to attaching external data to their NILS data extract.

Citation & Acknowledgments

The help provided by the staff of the Northern Ireland Longitudinal Study/Northern Ireland Mortality Study (NILS/NIMS) and the NILS Research Support Unit is acknowledged. The NILS/NIMS is funded by the Health and Social Care Research and Development Division of the Public Health Agency (HSC R&D Division) and NISRA. The NILS-RSU is funded by the ESRC and the Northern Ireland Government. The authors alone are responsible for the interpretation of the data and any views or opinions presented are solely those of the author and do not necessarily represent those of NISRA/NILS.

Dermot O’Reilly, Michael Rosato, Gemma Catney, Fiona Johnston, Maire Brolly. Cohort description: The Northern Ireland Longitudinal Study (NILS), International Journal of Epidemiology, Volume 41, Issue 3, June 2012, Pages 634–641, https://doi.org/10.1093/ije/dyq271

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