Samples of Anonymised Records from the U.K. Census 1991 and 2001 Integrating Census Microdata Workshop Barcelona th July 2005 Dr. Ed Fieldhouse Cathie Marsh Centre for Census and Survey Research. University of Manchester

The 1991 Samples of Anonymised Records Available for the first time after research into the confidentiality risk Two samples –Individual SAR Detailed geography (large LAs) 2% Sample –Household SAR Hierarchical, linked individuals - Detailed occupational information 1% Sample

Individual SAR content Geography –1991 – Large local authority areas – Regional Geography Migration –Distance moved –Region of origin

Demographic Marital Status – categories; categories Age banded –1991 single years (top coded 95+) –2001 Individual year to 15 –16-19; 20-24; 25-29; 30-44; –45-59; 60-64; 65-69; –70-74; single years; 95+ Ethnic group – categories – categories (E and W),14 Scotland, 2 N. Ireland Country of birth –1991 – 41 separate countries identified –2001 – 16 countries grouped Language (Scotland, Wales, Ireland) –Simplified in 2001

Socio-economic Economic activity Occupation – occupations –2001: 2000 SOC Minor categories, NS-SEC 38 valid categories, ISCO (10 categories) Industry – categories – categories Hours of work – single hours to 80+ Journey to work (distance/mode of transport) Year last worked/ever worked – new in 2001

Family and Household Household information –No of cars –No of earners –Housing tenure –Amenities, density, occupancy etc Family information –Family Type –Dependent Children in Family –Economic Position of Family Reference Person.

New or Improved Data compared to 1991 Improved highest qualification –4 categories Religion – varies considerably by nation –8 categories in England and Wales –10 in Scotland – current only –7 in Northern Ireland, plus religion brought up in General health –Good / fairly good / not good Caring –Hours caring, 3 bands –Number of carers in household

Research using the SARS Yaojun Li ‘Samples of Anonymized Records (SARs) from the UK Censuses: A Unique Source for Social Science Research’ Sociology, Jul 2004; 38:

Key analyses: modelling role of place Allows modelling of individual within the context of local authority area –multilevel modelling – 2 levels: Individual Local authority –Individual explanatory variables from SARs –Area-level explanatory variables from aggregate tables for each area –Extended to include information from the classification of small areas i.e. three level model. (Fieldhouse and Tranmer)

Modelling occupational attainment Anthony Heath used 1991 SARs to model occupational attainment of different ethnic groups –Logistic regression –Model used age, qualifications, UK born … –has been very influential in the Cabinet Office report on disadvantage in the labour market

Measures of deprivation based on individuals –Measure developed using Principle Components Analysis for individuals Variables drawn from Individual SAR –How do individual-based measures of deprivation in SAR areas differ from area- base measures? –How many ‘deprived’ individuals live in areas that are not deprived? –Do they differ from those in deprived areas? How?

Synthetic estimation of non- census data National survey data gives rates of serious illness by age and sex – but not at local authority level can impute to local authority areas (LA) using SARs (work by John Charlton) –predict probability of serious illness in survey; –explanatory variables in both survey and SARs; –Predictions from model (probability of illness) applied to each person in SAR within each LA area –Added to give estimate of total with illness

Migration in Scotland Modelling characteristics of migrants to Highlands and Islands Role of migration in mediating relationship between deprivation and ill-health –are healthy people more likely to move out of deprived areas? –what is the role of social housing? Work by Paul Boyle and colleagues

Household SAR 1% of households and all individuals Allows linkage between individual in households Similar detail to Individual SAR –Continuing discussion over ONS’ confidentiality concerns: large proportion of households population unique –heavy age grouping not acceptable as main requirement to understand household composition

The hierarchy of the household SAR Household 1 North West Social rented Household 2 Wales Owner occupier Person 1 HRP Female 28 No quals No LTILL Person 2 Son of HRP Male 12 N/A No LTILL Person 1 HRP Male 33 Degree No LTILL Person 2 Spouse of HRP Female 31 Degree P/T Employee No LTILL Person 3 Parent of HRP Female 72 No quals Econ Inactive LTILL

Release of household SAR Forthcoming release of Household SAR under special licence Unlikely to be available to overseas users No HH SAR for Northern Ireland and Scotland Current proposal (England and Wales) –two-year age bands –include all individuals in large households (up to size 12)

Key strengths of the SARs: Household file % sample, 540K individuals in 216K households Geography to standard region Supports analysis that relates individuals to family and household context, eg: –Ethnic differences in the influence of life-stage and partner’s characteristics on women’s employment –Ethnic differences in household composition, eg living patterns of the elderly –International comparisons of living arrangements

Summary of U.K. Census microdata Individual Samples 1991 (2%), 2001 (3%) 1% Household SAR 1991, 2001 Small area microdata Controlled access microdata Historical files 1961, 1966, 1971, 1981

The conditions –Data must not be redistributed without authorization. –The microdata are intended only for scholarly research and educational purposes. –Commercial use and redistribution of the microdata is strictly prohibited –Use of the microdata must follow strict rules of confidentiality –The microdata must always be safely secured. –Scholarly publications are permitted, and must be cited appropriately –Any violation of this license agreement will result in disciplinary action, including possible loss of employment