Transcript No Slide Title

The Scottish Longitudinal Study
A New Source for Scottish Research
Paul Boyle
The (Scottish) Longitudinal Study
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The England and Wales Longitudinal Study
(LS) established following 1971 Census
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To study occupational mortality and fertility
Scotland included originally
Withdrew for funding / sample size reasons
Original files destroyed
Re-establishing the SLS
• Funded by SHEFC and CSO (£1.5 million)
• Working in close collaboration with GRO(S)
• Borrowing as much as possible from ONS
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People
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Director: Paul Boyle
Project Manager (Technical): Lin Hattersley
Project Manager (Staff): Katherine Chisholm
Programmer: Zengyi Huang
Programmer: Joan Nolan
20 form pickers / clerical assistants
Research Fellow (Andy Cullis)
Research Fellow (Vernon Gayle)
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Management committee
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Paul Boyle (University of St Andrews)
Allan Findlay (University of Dundee)
Robin Flowerdew (University of St Andrews)
Sally Macintyre (University of Glasgow)
Steve Platt (University of Edinburgh)
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Steering committee
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David Orr (GROS)
Paul Boyle (SLS)
Ian Mate (GROS)
Muriel Douglas (NHSCR)
Lin Hattersley (SLS)
Rod Muir (ISD, PAC)
Louisa Blackwell (ONS)
• Secretary:
Katherine Chisholm (SLS)
What is the SLS?
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Provides linked data from the Scottish Census
and administrative records
Sampling based on 20 ‘semi-random’
birthdays
Initial sample drawn from the 1991 Census
Similar sample drawn from 2001 Census
Data sources
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Census
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• 1991 Census
• 2001 Census
• Including data on occupation,
economic activity, housing,
ethnicity, age, sex, marital status,
health, education, religion etc.
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Population data
• Immigration
• Emigration
Vital statistics
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Live births
Stillbirths
Infant mortality
Deaths
Widow(er)hoods
Marriages
Health data
• Cancer registrations
Data sources
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Census
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• 1991 Census
• 2001 Census
• Including data on occupation,
economic activity, housing,
ethnicity, age, sex, marital status,
health, education, religion etc.
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Population data
• Immigration
• Emigration
Vital statistics
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Live births
Stillbirths
Infant mortality
Deaths
Widow(er)hoods
Marriages
Health data
• Cancer registrations
• Hospital admissions
Strengths
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Sample size much larger than most surveys
• BHPS has ~10,000 people in GB
• SLS has ~278,000 members + ~518,000
household members in Scotland (1991)
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The census is compulsory
Linkage and trace rates are high
Includes those in communal establishments
Ability to link hospital admissions data to
socio-economic characteristics
Weaknesses
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Restricted range of variables
• Smoking
• Income
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Census information only collected every
decade
Not possible to return to the sample to ask
extra questions
The data are highly confidential
How does the SLS differ from the LS?
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Sample percentage larger (5.5% vs 1%)
20 SLS birthdays, but includes the four LS
birthdays
Fewer censuses captured
• SLS 1991 & 2001 (currently planned)
• LS 1971, 1981, 1991, 2001
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Some variables in the LS not coded in the SLS
• e.g. 1991 place of work
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Some variables in the SLS not coded in the LS
• e.g. hospital admissions and marriages
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The SLS is cheaper!
How far have we got?
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Identification of 1991 sample
• Electronic records extracted from 1991 Census
• Forms have been ‘picked’
• Flagging data passed to NHSCR
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Coding 1991 ‘difficult to code’ information
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Only originally coded for 10% Census
Designed interface for data input
Implementing occupation and industry coding software
62,000 basic coding completed
5,000 occupation and industry coding completed
Programming derived variables
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Linkage and ‘flagging’ through NHSCR
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278,359 have been actioned
241,591 have been flagged
2,316 of these are new births
611 are Scottish duplicates
10,258 have been sent to CR Southport to flag on
the English/Welsh database
12 are English duplicates
3,268 are dummy records
22,583 are in the process of being actioned
following further patient information
36 are no trace
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Vital statistics
• Specifications completed
• 1991 test data received
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2001 Census information
• Commissioned ‘top up’ coding of 65-74 year olds and 10year occupational coding
• Received pre-one number census download, to allow
flagging of imputed data
• Received post-one number census download, which includes
imputed characteristics
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Hope to ‘complete’ the job in 2004
Potential uses of the SLS
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Source data for academic research / social
policy / government departments etc.
Analysis of successive census data
• The links between social and geographical mobility
• The changing geographical distribution of the
ageing population
• Work patterns of men and women through the
lifecourse
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Analysis of successive event/health data
• Studies of changes in birth spacing
• Associations between fertility and later diseases
• The changing importance of different cancers
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Analysis of census and event/health data
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Occupational mortality and morbidity
Economic status and diabetes
Socio-economic factors and teenage pregnancy
Marital status differences in self-reported illness
Survival analysis of cancer by area deprivation and
occupation
• Housing tenure and respiratory disease
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Why are Scotland’s fertility rates significantly lower
than the rates in the rest of Britain?
How do in-migrants fare after arrival in Scotland?
Are older people becoming healthier in Scotland?
Are health inequalities widening between the better
and worse off in Scotland?
Given that Scotland has some of the highest lung
cancer rates in the world, what are the characteristics
of those who succumb to the disease?
Do unemployed people in Scotland ‘get on their bikes’
and move to places where unemployment rates are
low, or not?
Accessing the SLS
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A culture of data sharing
The data will be kept in a ‘secure environment’
A team will be established to provide access to the
data
A ‘data dictionary’ will be released once the dataset is
completed
Researchers will not receive individual-level SLS data
directly
Data will only be released as tabulations, statistical
summaries or aggregated data
In-house ‘safe-setting’ modelling of individual-level
data (by support team)
Why does Scotland need the SLS?
1991 deprivation in Scotland compared to England & Wales
1991 deprivation census variables in Scotland and England & Wales
1996 age-standardised all cause mortality per 100,000 in Europe
1996 age-standardised mortality for all malignant neoplasms per
100,000 in Europe
1996 age-standardised mortality for malignant neoplasm of the
trachea, bronchus and lung per 100,000 in Europe
Brief examples of LS research
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Does migration exaggerate the relationship between
deprivation and self-reported illness?
• Cross-sectional studies assume deprivation influences health
outcomes
• However, people move around
• Migration is selective, not random
• Health may influence migration
• Are the ill more likely to move towards deprived places, and
the well to move away from them?
Norman P, Boyle PJ and Rees P (forthcoming) Selective migration, health and
deprivation: a longitudinal analysis Social Science and Medicine
Age distribution of cohorts 1971, 1981 and 1991
SIRs 1991
SIRs 1971
SIRs 1991
Other related activities
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Adding local-area geographical data to
longitudinal datasets (ESRC)
• Ideally small area information would be available
• Raises disclosure risk and confidentiality problems
• A strategy for adding geographical variables /
identifiers which does not cause disclosure
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Training in longitudinal methods for the social
sciences (ESRC)
• Collaborative project with the University of Stirling
• Integrated programme of training activities
• Traditional training and distance learning package
The future…?
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Linkage of additional data into the SLS
• Historical IQ tests?
• Benefits data?
• Educational data?
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New forms of data access
• Web-based project design
• Teaching package with a single dataset
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British LS (BLS)
• Matching variables
• Creation of derived variables
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Future funding
• We only have resources to create the database
• Research and technical support funding will be
required
• Bid currently being considered by ESRC / MRC /
Scottish Executive
• Research group will provide longitudinal analysis
support