UK Wide Analysis

The NILS covers Northern Ireland only. However, similar studies exist for England and Wales (ONS-LS) and Scotland (SLS), opening the possibility of UK-wide analysis. The design of the three LSs is similar but there are important differences, such as the sampling fraction, which must be taken into account.

The Office for National Statistics Longitudinal Study (ONS-LS) is a representative 1% sample of the population of England and Wales (approximately 500,000 people), while the Scottish Longitudinal Study (SLS) is a representative sample of 5.3% of the Scottish population (around 274,000 people). The ONS-LS, incorporating data from all Censuses since 1971 has been successfully running for over 40 years, while the SLS, currently incorporating linkage of the 1991 and 2001 Censuses, has been available for about three.

Due to Data Protection concerns, the current agreements in place for the NILS and other LSs mean that it is not possible to access LS data outwith its respective secure environment. This means that to-date it has not been possible to fully combine datasets to allow comparisons between regions or to create a UK-wide sample.  Instead the only option has been to conduct separate analyses and then compare or combine the results on an ad-hoc basis. The Guide to Parallel & Combined Analysis for UK Longitudinal Studies details early work on this issue.

Work in the SLS-DSU by Prof Gillian Raab has resulted in a new methodology which means it is now possible to analyse data from two or more LS as though they were part of the same dataset.  This is achieved through a process called eDatashield, which is currently able to support all forms of GLM regression analyses. 

If you are interested in finding out more about eDatashield or would like to discuss using more than one LS for your study, please contact


We are very pleased to announce the new version of our data dictionary interface featuring: full variable information, advanced search options and the ability to save your own variable lists between sessions. We would greatly appreciate your thoughts on the new system so please find out more...


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