1. The Northern Ireland Longitudinal Study (NILS) BSPS Conference September 2007 David Marshall (NISRA)

2. PRESENTATION CONTENT 1. What is a Longitudinal Study? 2. What is the NILS? 3. Why does NI need an LS? 4. How Matching was completed 5. Security/Confidentiality 6. Projects

3. 1. WHAT IS A LONGITUDINAL STUDY?  A Study of the same group of people over time

4. Example | | | | | | | | | | | | | | | | | | | | | | | 1991 2001 2011 Census Birth of Child StillbirthDivorceMarriageCancer 27-year old Female in 1991 Death Address Change Birth of Child Address Change

5. 2. WHAT IS THE NILS?  Database of individuals and their life events that can be accessed (in a controlled way) by researchers  Began work in 2003  Launched in December 2006  Funded by the Health Department in NI  Steering Group

6. 2. WHAT IS THE NILS? cont’d  104 NI birth dates (4 LS, 20 SLS)  2001 Census-based  Main Data Sources  Demographic Data from Health Registrations  2001 Census  Births/Deaths Registrations  Property Valuations

7. E&W LS SLSNILS Number Dates 420104 Size500,000(1%)300,000(5%)500,000(28%) Start Date 197119912001 Number of Censuses 421 Data on all 3 LSs Births to sample mothers Births of sample members Deaths of sample members Immigrants Embarkations Widow(er)hoods

8. E&W LS SLSNILS Births to Sample Fathers ✔ Stillbirths/ Infant Deaths ✔✔ Internal Migration ✔ Cancer Registrations ✔✔ Hospital Episodes ✔ Education✔ Marriages✔✔ Claimant Count ✔

9. 2. NILS Mortality Dataset  Additional exercise  All deaths post 2001 linked to Census  65,000 deaths linked  Population at risk is 2001 Census  Compared to 20,000 in NILS main sample  Many of death-based analyses will probably be carried out on this until further information included in NILS

10. 3. WHY DOES NI NEED AN LS?  Different People  Different issues  Different Policies

11. 4. HOW MATCHING WAS PROCESSED  Data Preparation  Automatic Matching & scoring Exact Matching Exact Matching ‘Fuzzy’ Matching ‘Fuzzy’ Matching  Manual Confirmation Confirmation Searching Searching

12. 4. MATCHING LEVELS Approximately :  50% of matches were exact  30% very good fuzzy matches  10% manual confirmation on fuzzy matches  10% Manual searches of database  87.4% unadjusted match rate  96.4% adjusted for Census imputation, accuracy of health service records for Census imputation, accuracy of health service records

13. 5. SECURITY/CONFIDENTIALITY  Processed Under Census Legislation  Personal Data & Sensitive Personal Data  Research Approvals Group and application process  Researchers only allowed access to anonymised records  Data Held in Secure Environment  Closed network  Biometric access to PCs  No output media allowed (CDs, Data Sticks, Print-outs)  All output checked for Disclosure

14. 6. NILS Projects  Temperature-related mortality and housing  Religion / denomination differences in mortality  Impact of non-linkage using NILS mortality

15. Some test findings so far….  Migration ‘Stickiness’  Cultural and educational variables in fertility analyses important  Carers have lower mortality  Mortality Rates by Religion  Suicide risk is strongly related socio- economic disadvantage and social support at an individual level & area factors have no independent effect

16. 6. ESRC/RDO Money for Researchers  £300,000 for short research projects  to raise awareness of NILS  Application Process (2 stage)

17. SUMMARY  28% Sample of NI Population  Includes 2001 Census, birth/death and heath service registration data  Data held securely within legislative boundaries  Projects started and first paper accepted in academic journal

18. The Northern Ireland Longitudinal Study (NILS) BSPS Conference September 2007 David Marshall (NISRA)

19. The Northern Ireland Longitudinal Study (NILS) nils.nisra@dfpni.gov.uk www.nisra.gov.uk/nils nils.nisra@dfpni.gov.uk www.nisra.gov.uk/nils nils.nisra@dfpni.gov.uk www.nisra.gov.uk/nils

20. Contextual DataNILS Core DataEvents Central Services Agency Key demographic information on NILS members (514,000 live) @ Census Date New members (36,000) 2001 Census Database 1991 Census Births Data (baby linked to Birth Registration) 2001 births onwards Babies linked to Birth Reg. Pre 2001 Deaths Births to MothersBirths to Fathers Stillbirths & Infant Deaths Migration (Immigrants, Emigrants, Re-Entrants & Within NI Movers) VLA/Rating Data POINTER Address Database