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Linking your data

The English Longitudinal Study of Ageing (ELSA) is a collaboration led by University College London involving the National Centre for Social Research (NatCen), The Institute for Fiscal Studies, The University of Manchester, and The University of East Anglia. Together these five organisations form the ELSA collaborators and act as joint Data Controllers, making decisions about how the data are collected, processed and looked after. During your ELSA interview, we ask for your permission to link your survey information to health and economics data from other sources including:

Hospital records including dates of admission and consultations, treatments received, and referrals made whilst as an inpatient, outpatient, or during emergency care.
Primary care records including doctor and nurse consultations, diagnoses received, treatments given, and referrals made.
Cancer records including diagnoses, treatments, and outcomes. 
Mortality records including date of death, whether the individual died in an NHS hospital, and the main and secondary cause of death.
National Insurance contributions.
State benefits and tax credits.
Tax and employment or self-employment records.
Savings and pensions.

These data are held by NHS England, the Department for Work and Pensions and HM Revenue and Customs, and we call them “administrative data”.

Linking to administrative data enables us to build a more complete picture of your life to allow more complex research questions to be answered such as how your lifetime earnings or your past hospital stays impact on your experience of ageing without you having to spend a lot of time telling us this information yourself. 

If you give us permission to link your data, the process will be managed very carefully to ensure your privacy is maintained. Only ELSA collaborators will be able to see your name, address, and other identifiers alongside your study answers and administrative data. Access will be controlled so that only individuals who need to see information that identifies you will be able to.

If you agree to linkage, other researchers will be allowed to use your data for public good purposes in a form that protects your identity.

The data linkage journey

This is how the process works:

If you give consent to data linkage you will be asked to provide some information (personal identifiers) during the ELSA study interview that can be used to find your administrative records like your name, address, date of birth, National Insurance Number, and National Health Service (NHS) Number.

The ELSA Collaborators separate these personal identifiers from your other study answers and pass them over to third-party organisations who hold your administrative data or who carry out the linkage (linkage organisations). Separating these personal identifiers from your study answers minimises the chance that you could be identified. Provided you have given consent, these details will be sent to the following organisations:

              •    NHS England who manage your NHS health data (including mortality records) 
              •    NHS Digital Health and Care Wales who manage NHS data sharing  
              •    The Office for National Statistics Data Access Platform who carry out data linkage for the 

                   purposes of linking to information from HM Revenue and Customs and the Department for
                   Work and Pensions
              •    University of Leicester who manage and link environmental data

The linkage process will be co-ordinated either directly by the ELSA collaborators or on our behalf by the UK Longitudinal Linkage Collaboration. All data are linked in a way that third-party organisations cannot see your name, address, and other personal identifiers alongside your study answers to minimises the chance that you could be identified.

Your name and address and other personal identifiers you have given us (such as NHS number or National Insurance Number) are separated from your ELSA study answers by the ELSA collaborators and sent to the linkage organisation along with your unique ELSA ID number. The third-party organisations will use your name, address, and other personal identifiers to find your administrative data. Then your administrative data matched with your unique ELSA ID number will be sent back to the ELSA collaborators or to a secure repository to be matched back to your study answers via your unique ELSA ID number to create a new set of linked research data which contains your study answers matched to your administrative data but no directly identifiable information. Researchers who are accredited under the Digital Economy Act will be able to apply to use these linked data in a secure, controlled environment to carry out research for the public good. Examples of how your data have been used to benefit society can be found in the ELSA 20th Anniversary Report:

The graphic below summarises the way that your data are linked, and which organisations are sent your information. The process is complex which is necessary to protect your identity, so the graphic is a simplification of the way that this works. The privacy notice for the Longitudinal Linkage Collaboration contains more detail. 


Why the linked data are needed

Hospital Episode Statistics

Although we collect information about your health during the interview, there is not enough time to collect detailed information about your use of health services. The Hospital Episode Statistics contain records of all admissions, outpatient appointments and accident and emergency attendances at NHS hospitals in England. By linking your information to these records, the ELSA researchers are able to analyse the data to improve our understanding of how and why the use of hospital services varies among the over 50s. Because you tell us about your health, we can try to isolate the difference in hospital use over and above any differences in health and other characteristics across different people. This will enable us to provide evidence on how well spending on health and social care is allocated across different types of people and to look at inequalities in quality of care. The data will also be used to assess the impact that stays in hospital may have on other important aspects that affect your quality of life.

Mortality data

ELSA is a study about ageing and how the ageing process varies across different types of people. In order to understand what happens to people in later life, it’s important that we know when they have died and how they have died. Linking to mortality records gives us accurate information on cause and date of death. Mortality data is sourced from civil registration data.

Cancer data

Cancer Registration data is collected by National Disease Registration Service. These data contain information about the type of cancer or condition and any treatment that you may have.

Linking your information to these records will enable us to analyse the data to improve our understanding about who is affected by cancer, inequalities in cancer care and how having cancer impacts on other aspects of your life.

State benefits and tax credit data

The UK system of state benefits is complex, and we recognise that it is difficult for you to accurately tell us how much income you are receiving from different sources and how long you’ve been receiving them. Linking the information that you give us with administrative data gives us additional information about your income sources over a long period of time (all of which could not be collected as part of a survey). There is concern that some people who may be entitled to benefits may not be claiming them and we would like to understand why. Combining information on your circumstances with accurate information on which benefits you may be receiving allows us to analyse which factors may be affecting take-up. The data will also be used to look at policy issues relating to benefits. For example, we are able to see what happens when the government introduces a new benefit or changes an existing benefit.

National Insurance records

Administrative data from National Insurance records provides a historical picture of your income and a detailed historical picture of your contributions to the National Insurance system. Although we collect information on your current income in the interview, it is important to understand the way that your income may have changed over your lifetime and how this has affected your current circumstances. Understanding your contribution to the National Insurance system allows us to calculate how much you could be entitled to receive from the State Pension. Knowing this means that we can look at how this may affect how long you continue to work, how much you save in other forms and what the impact may be on other aspects of your life such as your health.


Employment and tax and income data

Many people have incomes from a variety of different sources. People may have income coming from employment, self-employment, state pensions or other benefits, private pensions, or investments. It can be difficult to accurately record the different incomes people have and how they change over time. By linking your information to historical administrative records, researchers will be able to accurately measure people's incomes over a longer period of time than is possible in the ELSA interview. We will also be able to see periods of time when you may have been employed in the past as well as information about employers. This can also be done over a long period of time. This will enable researchers to understand how important different types of income are for people's finances, and how people’s health and social participation, and other important parts of people's lives are linked to employment and income, and whether people working for particular types of employers face different challenges later in their lives.​

How to opt in or out 

The first time you take part in ELSA, you will be asked to provide consent for us to link to each of the types of data listed above. You can choose to consent to all of them, or some of them, or none of them. For each type of link, your interviewer will provide you with information which explains the type of data that is collected, the purpose that it is collected for, how we control access to this information, and how to withdraw your consent if you change your mind. 

After that first time, you will be asked at each interview whether you still consent to each type of link.

You can withdraw your consent to any one or all of the different types of data. You can also withdraw your consent at any time outside of the interview by:

  • Writing to us at NatCen Social Research, Unit 15, Ashton Gate, Ashton Road, Romford, Essex, RM3 8UF or

  • Emailing


Please tell us which records you no longer wish to consent to link; information to allow us to correctly identify you in our records (your name and DOB and a postal address, email address or telephone number in case we need any further information to complete your request.


You are free to withdraw your consent to linkages at any time without giving a reason. It will not be possible to delete linked data  about you that has already been added to the research database, however no new linked data about you will be added to the research database from the moment the team has confirmed your withdrawal.

To get in touch you can email us at or call our Freephone number 0800 652 4574 (Monday to Thursday 9am to 8pm, Friday 9am to 5pm, Saturday 10am to 4pm.

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