ONS Longitudinal Study

ONS LS, LS

The ONS Longitudinal Study (LS) was established in 1974 by taking a sample of records from the 1971 Census for England and Wales of all those born on one of four dates of birth. This original sample has been continuously augmented since 1971.

New members enter the study through one of three routes if born on one of the four dates of birth: inclusion on a census form; birth registration; or registration with the NHS. The study now includes information on more than 1.2 million different individuals.

The study holds linked census information for this group across time, as well as information on events such as having a baby (for female study members), migrating to or from England and Wales, being widowed and dying.

The strengths of the study include: the robustness of the sample size, around 500,000 at any one census; the relatively high rates of retention and response; the range and stability of the information available for analysis over time; the inclusion of census information on co-residents of study members; and the help of dedicated user support teams.

The study was originally set up to meet a need for better data on occupational mortality and fertility patterns. The LS addresses these needs and many more: it has supported research across multiple themes, including ageing, care-giving, deprivation, ethnicity, health inequality, migration and social mobility.

Inequality in health and mortality remains one of the most prominent topics the study is used for. LS-based research has contributed to a number of national reviews of health inequality, including Fair Society Healthy Lives (The Marmot Review) in 2010. The LS is also the source used by ONS to create and publish National Statistics on inequality in life expectancy by socio-economic position.

Sample design

The LS has a 1% dynamic sample of all persons of any age or gender, identified as having an LS date of birth (one of four dates, spread through the year) and usually resident in England and Wales. New members enter the study through one of three routes if born on one of the four dates: inclusion on a census form; birth registration; or registration with the NHS. 

The study has been maintained as a continuous multi-cohort through the addition of new births and immigrants with the same birth date, and includes individual-level data from five Censuses (1971, 1981, 1991, 2001, 2011) as well as linked information on births, deaths and cancer registrations (up to 2015).  All information collected on the census forms is included in the LS.

Linked data

The LS database is updated every year with event data from a number of sources, including: deaths of LS members (up to eight causes of death [up to 16 from 2014]); LS members being widowed; female LS members giving birth; and LS members being diagnosed with cancer (up to 2015).

Management and funding

The LS is maintained and updated by the LS Development Team at the Office of National Statistics, part of the Centre for Ageing and Demography.

ONS and the Economic and Social Research Council (ESRC) co-fund the annual processing that adds life events data from civil registration and NHS registration systems. Funding for the addition of 2021 Census data is being provided by ONS’s Census & Data Collection Transformation Programme.

CeLSIUS is funded by the ESRC.

Accessing the data

LS data is available for free to researchers who can show that their work is in the public interest and who have successfully applied to become an Accredited Researcher .

CeLSIUS will guide and support researchers throughout the application processes and during the research project. To discuss a potential research project, please contact the Centre for Longitudinal Study Information and User Support (CeLSIUS).

Cohort profile

Nicola Shelton, Chris E Marshall, Rachel Stuchbury, Emily Grundy, Adam Dennett, Jo Tomlinson, Oliver Duke-Williams, Wei Xun, Cohort Profile: the Office for National Statistics Longitudinal Study (The LS), International Journal of Epidemiology, Volume 48, Issue 2, April 2019, Pages 383–384g,