The Northern Ireland The Northern Ireland Longitudinal Study (NILS) Longitudinal Study (NILS)

BSPS Conference BSPS Conference September 2007September 2007

David Marshall (NISRA) David Marshall (NISRA)

PRESENTATION CONTENTPRESENTATION CONTENT

1.1. What is a Longitudinal Study?What is a Longitudinal Study?

2.2. What is the NILS?What is the NILS?

3.3. Why does NI need an LS?Why does NI need an LS?

4.4. How Matching was completedHow Matching was completed

5.5. Security/ConfidentialitySecurity/Confidentiality

6.6. ProjectsProjects

1. WHAT IS A LONGITUDINAL 1. WHAT IS A LONGITUDINAL STUDY?STUDY?

A Study of the same group of people over timeA Study of the same group of people over time

ExampleExample

| | | | | | | | | | | | | | | | | | | | | | | 1991 2001 2011

CensusCensusCensus Birth ofChild

Stillbirth DivorceMarriage Cancer

27-year old Female in 1991

Death

AddressChange

Birth ofChild

AddressChange

2. WHAT IS THE NILS?2. WHAT IS THE NILS?

Database of individuals and their life Database of individuals and their life events that can be accessed (in a events that can be accessed (in a controlled way) by researcherscontrolled way) by researchers

Began work in 2003Began work in 2003 Launched in December 2006Launched in December 2006 Funded by the Health Department in NI Funded by the Health Department in NI Steering GroupSteering Group

2. WHAT IS THE NILS? cont’d2. WHAT IS THE NILS? cont’d

104 NI birth dates (4 LS, 20 SLS)104 NI birth dates (4 LS, 20 SLS) 2001 Census-based2001 Census-based Main Data SourcesMain Data Sources

Demographic Data from Health RegistrationsDemographic Data from Health Registrations 2001 Census2001 Census Births/Deaths RegistrationsBirths/Deaths Registrations Property ValuationsProperty Valuations

E&W LSE&W LS SLSSLS NILSNILS

Number Number DatesDates

44 2020 104104

SizeSize 500,000 500,000

(1%)(1%)

300,000300,000

(5%)(5%)

500,000500,000

(28%)(28%)

Start DateStart Date 19711971 19911991 20012001

Number of Number of CensusesCensuses

44 22 11

Data on Data on

all 3 LSsall 3 LSs

Births to sample mothersBirths to sample mothers

Births of sample membersBirths of sample members

Deaths of sample membersDeaths of sample members

ImmigrantsImmigrants

EmbarkationsEmbarkations

Widow(er)hoodsWidow(er)hoods

E&W LSE&W LS SLSSLS NILSNILS

Births to Sample FathersBirths to Sample Fathers ✔✔

Stillbirths/ Infant DeathsStillbirths/ Infant Deaths ✔✔ ✔✔

Internal MigrationInternal Migration ✔✔

Cancer RegistrationsCancer Registrations ✔✔ ✔✔

Hospital EpisodesHospital Episodes ✔✔

EducationEducation ✔✔

MarriagesMarriages ✔✔ ✔✔

Claimant CountClaimant Count ✔✔

2. NILS Mortality Dataset2. NILS Mortality Dataset

Additional exerciseAdditional exercise All deaths post 2001 linked to CensusAll deaths post 2001 linked to Census 65,000 deaths linked65,000 deaths linked Population at risk is 2001 CensusPopulation at risk is 2001 Census

Compared to 20,000 in NILS main sampleCompared to 20,000 in NILS main sample Many of death-based analyses will probably be Many of death-based analyses will probably be

carried out on this until further information carried out on this until further information included in NILSincluded in NILS

3. WHY DOES NI NEED AN LS? 3. WHY DOES NI NEED AN LS?

Different PeopleDifferent People

Different issuesDifferent issues

Different PoliciesDifferent Policies

4. HOW MATCHING WAS PROCESSED4. HOW MATCHING WAS PROCESSED

Data PreparationData Preparation Automatic Matching & scoringAutomatic Matching & scoring

• Exact MatchingExact Matching• ‘‘Fuzzy’Fuzzy’ Matching Matching

ManualManual• ConfirmationConfirmation• SearchingSearching

4. MATCHING LEVELS4. MATCHING LEVELS

Approximately :Approximately :

50% of matches were exact50% of matches were exact 30% very good fuzzy matches30% very good fuzzy matches 10% manual confirmation on fuzzy matches10% manual confirmation on fuzzy matches 10% Manual searches of database10% Manual searches of database

87.4% unadjusted match rate87.4% unadjusted match rate 96.4% adjusted 96.4% adjusted

for Census imputation, accuracy of health service for Census imputation, accuracy of health service recordsrecords

5. SECURITY/CONFIDENTIALITY5. SECURITY/CONFIDENTIALITY

Processed Under Census LegislationProcessed Under Census Legislation Personal Data & Sensitive Personal DataPersonal Data & Sensitive Personal Data Research Approvals Group and application processResearch Approvals Group and application process Researchers only allowed access to anonymised Researchers only allowed access to anonymised

recordsrecords Data Held in Secure EnvironmentData Held in Secure Environment

Closed networkClosed network Biometric access to PCsBiometric access to PCs No output media allowed (CDs, Data Sticks, Print-outs)No output media allowed (CDs, Data Sticks, Print-outs) All output checked for DisclosureAll output checked for Disclosure

6. NILS Projects6. NILS Projects

Temperature-related mortality and housingTemperature-related mortality and housing

Religion / denomination differences in Religion / denomination differences in mortalitymortality

Impact of non-linkage using NILS mortality Impact of non-linkage using NILS mortality

Some test findings so far….Some test findings so far…. Migration ‘Stickiness’Migration ‘Stickiness’

Cultural and educational variables in fertility Cultural and educational variables in fertility analyses importantanalyses important

Carers have lower mortalityCarers have lower mortality Mortality Rates by ReligionMortality Rates by Religion

Suicide risk is strongly related socio-economic Suicide risk is strongly related socio-economic disadvantage and social support at an individual disadvantage and social support at an individual level & area factors have no independent effect level & area factors have no independent effect

6. ESRC/RDO Money for 6. ESRC/RDO Money for ResearchersResearchers

£300,000 for short research projects£300,000 for short research projects

to raise awareness of NILSto raise awareness of NILS

Application Process (2 stage)Application Process (2 stage)

SUMMARYSUMMARY

28% Sample of NI Population28% Sample of NI Population

Includes 2001 Census, birth/death and heath Includes 2001 Census, birth/death and heath service registration dataservice registration data

Data held securely within legislative Data held securely within legislative boundariesboundaries

Projects started and first paper accepted in Projects started and first paper accepted in academic journalacademic journal

The Northern Ireland The Northern Ireland Longitudinal Study (NILS) Longitudinal Study (NILS)

BSPS Conference BSPS Conference September 2007September 2007

David Marshall (NISRA) David Marshall (NISRA)

The Northern Ireland The Northern Ireland Longitudinal Study (NILS) Longitudinal Study (NILS)

nils.nisra@dfpni.gov.uknils.nisra@dfpni.gov.uk

www.nisra.gov.uk/nilswww.nisra.gov.uk/nils

Contextual Data NILS Core Data Events

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 Mothers

Births to Fathers

Stillbirths & Infant Deaths

Migration (Immigrants, Emigrants,

Re-Entrants & Within NI Movers)

VLA/Rating DataPOINTER

Address Database