1. The ONS Longitudinal Study - plans for the 2011 Census and beyond
Jim Newman, Head of Longitudinal Study Development, Office for National Statistics

2. Outline Overview of the ONS Longitudinal Study (ONS LS)
Plans to link 2011 Census data to the ONS LS
Future of the ONS LS after the 2011 Census
ONS LS resources and further information

3. Definition of the ONS LS
‘The ONS Longitudinal Study is a study
containing linked census and life events data on
a one per cent sample of the population of England and Wales.’
Note: A study, not a survey

4. Structure of the ONS LS 1971 Census 1981 Census Entries Linked events
530,000 sample members selected
513,000 traced
1981 Census
536,000 sample members selected
528,000 traced
1991 Census
544,000 sample members selected
535,000 traced
2001 Census
540,000 sample members selected
536,000 traced
2011 Census
5??,000 sample members selected
5??,000 traced
Entries
264,000 new births
164,000 immigrants
Exits
233,000 deaths
39,000 emigrants
Linked events
253,000 births to sample women
2,000 infants deaths to sample women
80,000 widow(er)hoods
110,000 cancer registrations

5. Census samples available for analysis
1971
1981
1991
2001
513,000
528,000
535,000
536,000
1 census
408,000
420,000
2 censuses
418,000
327,000
3 censuses
331,000
256,000
4 censuses
Total traced LS members: 1,036,000

6. Study cycle of an LS member
1950
1970
1980
2010
1990
2000
2001 Census
1991 Census
1981 Census
1971 Census
Born 1955
Entry
Birth #1
Birth #2
Events
Exit
Re-entry
Death of spouse
Cancer
Death
(Exit from study)

7. Census data Life event data
ONS LS data
What does the
ONS LS contain ?
Geographic data
Ethnicity
(1991 & 2001)
Self-rated
health (2001)
Long-term limiting
illness (1991 & 2001)
Religion (2001)
Care giving (2001)
Migration &
travel to work
Education
(all levels 2001)
Census data
Marital status & family type
Housing & amenities
Occupation &
social class
Economic
activity
Life event data
Infant deaths to
sample mothers
Still births to
Live births to
Widow(er)hoods
Immigrations
Emigrations
(recorded)
Births of ONS LS
members
Cancer
registrations
Deaths
(cause specific)
Age, sex & country of birth

8. High level plan to link 2011 Census data
Census Day, 27 March 2011 2
Delivery of 2011 Census link extract data files starts, one per delivery group 3
Delivery of full 2011 census data extract 4
Reporting to 2011 Census QA begins 5
Final processing report to Census QA covering all delivery groups 6
Full ONS LS census-to-census linkage analysis complete (equivalent to LS10 from 2001 Census) 7
Beta testing of ONS LS database incorporating 2011 Census data starts 8
Launch of ONS LS database incorporating 2011 Census data starts

9. 2011 Census quality reporting
Post-2001, ONS LS-based adjustment to population estimates
2011 Census, report to Census during processing
Undercount
who didn’t appear in the census, broken down by:
age
sex
location
marital status
ethnicity, etc.
Overcount
who appeared more than once in the census, and why
within household multiples, e.g. internet and paper response
students at home and term-time addresses
people at home and communal establishment
movers enumerated at old and new addresses
children of separated parents at both addresses, etc.

10. Questions in the 2011 Census
New questions in 2011:
second residence
number of bedrooms
civil partnerships
Questions being asked for the second time in 2011:
caring responsibilities
self-rated health
religion

11. Questions in the 2011 Census
Questions on the themes of nationality/ethnicity/migration/religion:
country of birth
if born abroad, month and year of arrival to live in UK (’71)
if arrived in the preceding year, intended length of stay (new)
national identity (new)
ethnic group
main language (new)
religion
address one year ago
passport held (new)

12. Future direction for the ONS LS
Short to medium term
Fully exploit the new LS database
Expand LS user base, particularly within Government
Update annually with a fifth decade of life events data
Closer integration with sister studies in Scotland and Northern Ireland
Long term
What will we do in 2021?

13. Centre for Longitudinal Study Information and User Support
LS resources and further information
ONS website
Centre for Longitudinal Study Information and User Support