The Northern Ireland Longitudinal Study (NILS) has been formally available to researchers since the end of 2006. It comprises two major data linkage studies: the NILS and the Northern Ireland Mortality Study (NIMS). These were developed by the Northern Ireland Statistics and Research Agency (NISRA) and are maintained and managed by them as a resource for research.

Dr Ian Shuttleworth is currently Director of the ESRC-funded NILS Research Support Unit (NILS RSU) and is also a member of the NI Census Advisory Group and the ESRC Census Advisory Committee.

The selection into the study is based on birth date (day and month): 104 dates throughout the year were selected and if an individual’s date of birth coincided with one of these they were included in the sample. The sample is large - around 28% of the Northern Ireland population (approximately 500,000 individuals) and accounting for approximately 50% of households. The NILS 'core' data  are obtained from approximately 500,000 persons drawn from the Health Card Registration data and then  linked to data from Census returns (1991, 2001 and 2011), Vital Events (births and deaths), Migration and Property data. The result is a 30 year plus longitudinal data set which is regularly being updated. In addition to this rich resource there is also the potential to link further Heath and Social care data in our distinct linkage projects (DLPs).