Conference Programme• 10.00 Introduction to the Samples of Anonymised Records - Keith

Spicer, ONS

• 10.30 CCSR's role in providing SAR's support - Jo Wathan, CCSR

• 11.00 Refreshments

• 11.20 Dynamics and Diversity: Ethnic Employment Differences in England and Wales - Stephen Drinkwater, University of Surrey

• 11.45 Household membership, ethnic group and subnational geography - Abdelouahid Tajar, CCSR

• 12.10 Using the 2001 Census Microdata for Evidence Based Policy-Making - Chris Gardiner and Lisa Buckner, Sheffield Hallam University

• 12.35 Discussion, followed by Lunch at 12:45.

Conference Programme• 13.30 Migration in 2001 Census - Tony Champion, University of

Newcastle

• 14.00 The drivers of individual migration: an analysis of individual data from the 2001 Census - Nick Bailey and Mark Livingston, University of Glasgow

• 14.30 Discussion

• 14.45 Refreshments

• 15.00 Access to the Controlled Access Microdata Sample (CAMS) - Michelle Clift-Matthews, ONS

• 15.15 Discussion on lessons learnt and approach for 2011 Census Microdata – Panel session

• 16.00 Close

Introduction to Samples of Anonymised Records (SARs)

Keith Spicer – ONS

SARs User Group Meeting 15 July

Samples of Anonymised Records (SARs)

• Data sets of Census microdata (individual and household records)

• 1991 OPCS provided 2% individual SAR and 1% household SAR

• 2001 ONS provided 3% individual SAR, covering UK, and shortly 1% household SAR – and to cover smaller areas (less detail) a 5% dataset including LA geography

Confidentiality

• Pledge to respondents on Census form• National Statistics Code of Practice:

‘……a guarantee that no statistics will be produced that are likely to identify an individual..…’

- Impact on what we provide and how we provide it

- Protection against disclosure by two means- making data safe

- safe setting

Confidentiality – making data safe

• Measure of risk:

–Proportion of sample cases that are unique in the population, based on a few selected variables

• Benchmark for ‘safe data’ where 1% of sample are population uniques

• Achieved by recoding and data perturbation

Confidentiality – safe setting

• Used for data with more detail (disclosive)

• ONS data laboratories

• Researchers application

• Outputs and publications checked by ONS

SARs Products

• 3% sample of individuals, access through CCSR (Individual Licensed SAR)

• 3% sample of individuals, controlled access microdata sample (CAMS) – in-house SARs

• 1% sample of households – CAMS

• 1% sample of households, access under special licence through UK Data Archive

• 5% sample of Small Area Microdata (SAM)

Balance between Risk and Data Utility

Less Utility of Data More

Lev

el o

f R

isk

Non-disclosive

Disclosive

Individual Licensed

SAR

CAMS

Household SAR (Special

Licence)

Progress and Achievements

Individual Licensed SAR

• Version 2 released in April– Religion– Full ethnic group– 81 instead of 25 occupational categories– COB categories expanded from 7 to 16

Progress and Achievements

Controlled Access Microdata (CAMS)

• Opportunities to provide more detailed datasets• Data lab in Titchfield – and other sites

• Individual CAMS

• Household CAMS

• Additional responsibilities of researchers• Lab used for 14 different research applications

so far (4 pending)

Progress and Achievements

Household SAR

• 1% population uniques not achievable without seriously damaging data utility

• Recognised need to provide useful file for desktop access

• Combination of data protection and access conditions• Some protection to data (recoding and light

perturbation)• Proposed access through ONS Special Licence

Household SAR – Special Licence

• Will be available through UK Data Archive

• Applications scrutinised carefully by ONS– Professional researcher with institutional support– Purpose for statistical research only– Intention to publish, and research of value to the field

• High level of responsibility and trust of researchers

• Sanctions for institutions where users contravene licence conditions

Still to do…….

• Household SAR under Special Licence– August 2005

• Small Area Microdata– September/October 2005

More Information

• www.ccsr.ac.uk/sars - CCSR’s SARs website

• Email sars@ons.gov.uk

• CAMS User Guide – also see our website www.statistics.gov.uk/census2001/sar_cams.asp for Confidentiality Guidelines and other SARs details