conference programme 10.00 introduction to the samples of anonymised records - keith spicer, ons...
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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
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