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The ARGUS Software of the SDCproject
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Statistics Netherlands. Washington, August 1999. Statistical ... Co-operation between The Netherlands, Italy ( Spain) and UK. General aims of SDC project ... – PowerPoint PPT presentation
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Title: The ARGUS Software of the SDCproject
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The ARGUS Software of the SDC-project
- Anco Hundepool
- Statistics Netherlands
- Washington, August 1999
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Statistical Disclosure Control
- the balance between the need for (more and more)
information and - the privacy of the respondents
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Statistical Disclosure Control
- Need for detailed micro data files
- electronic publications
- computing power of users
- Need for more detailed tables
- But....!!!
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Statistical Disclosure Control
- Protection of privacy of respondents
- persons, enterprises, institutions
- Respondents must be able to trust Statistical
Offices! - Risks
- Intruders/ hackers
- Accidental recognition
- Advanced record linkage techniques
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Statistical Disclosure Control
- Produce safe datafiles and tables
- Apply data modification techniques
- Preserve as much information
- Implemented in ARGUS!
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Framework of developmentof ARGUS
- SDC project
- partly subsidised by EU (4th Framework)
- Co-operation between The Netherlands, Italy
(Spain) and UK
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General aims of SDC project
- Methodological research in SDC
- microdata, tables
- concerning statistics, OR
- geographical data
- (general) SDC Software development
- microdata (m-ARGUS)
- tables (t-ARGUS)
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SDC project members
- Netherlands
- CBS (ARGUS)
- TU-Eindhoven (OR for microdata)
- Italy
- Istat (with Univ. of Rome)(Research/testing)
- CPR-Padova (with Univ. Tenerife)(OR for tabular
data)
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SDC project members
- UK
- ONS (data)
- Univ. Manchester (with Univ. of
Southampton)(Research on SARs) - Univ. Of Leeds (Geographical data)
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Main software developed in SDC-project
- m-ARGUS (CBS and TUE)
- micro data
- t-ARGUS (CBS and CPR)
- tabular data
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Ideas of m-ARGUS
- Intruder uses information of identifying
variables (e.g. region, sex, age, education,
occupation) to identify records. - This leads to the sensitive information
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m-ARGUS
- Levels of protection
- public use files (PUF)
- micro files for researchers (MUC)universities,
contract etc. - safe-setting
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Ideas of m-ARGUS
- a list of combinations of identifying variables
must checked - find value combinations that are unsafe
- e.g. a x b x c
- threshold depends on level of protection
- Public use files
- Micro data for researchers (contract)
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Ideas of m-ARGUS
- eliminate the unsafe combinations
- by global recoding (age - agegroup, region
- province) - local suppression (imputing missings)
- interactively/automatically
- with minimum information loss (entropy)
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m-ARGUS
- For microdata
- Developed in Borland C
- Windows-95/98
- Version 3.0 last SDC-version
- interactive/automatic global recoding
- automatic local suppression
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Features of m-ARGUS
- can handle large microdata files
- only tables derived from microdata are being
used - flexible global recoding
- options for automatic mix of global recoding and
local suppression (TU Eindhoven)
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Addit. features of m-ARGUS
- Micro-aggregation
- Top/Bottom coding
- Rounding
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m-ARGUS
metadata
microdata
Generate tables
Recoding schemes
Global recoding
Local suppression
Micro aggregation
Top/bottom coding
Rounding
Report
metadata
microdata
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m-ARGUS input data
- Data Fixed format ASCII
- Metadata
- Name
- Position
- Missing values (2)
- Identification level
- Hierarchical coding
- Codelist (opt.)
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Using m-ARGUS
- reading data file
- generating tables
- apply global recodes
- local suppression
- generate safe file
- generate report
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t-ARGUS
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Ideas of t-ARGUS
- identification of sensitive cellsusing e.g.
dominance rule - at least n (e.g. 2) contributors to a cell
- sum of largest 3 contributors 75(one large
contributor could recalculate the contribution of
its competitor) - easy part
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Ideas of t-ARGUS
- Eliminate/protect sensitive cells(hard part)
- by applying SDC techniques
- table redesign
- cell suppression
- rounding
- interactively and/or automatically
- with minimum information loss (e.g. cell weights)
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Ideas of t-ARGUS
- cell suppression in tables with marginals
- identify primary sensitive cells
- protect primary cells by suppressing additional
(secondary) cells to prevent recalculation (to
some approximation) - with minimal information loss (CPR)
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t-ARGUS
- 3-D tables
- interactive table redesign
- primary secondary cell suppression
- optimisation routines for automatic cell
suppression - rounding
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t-ARGUS
metadata
microdata
tabulation
codelists
redesign
rounding
suppression
report
Safe table
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Features of t-ARGUS
- Initial run through microdata
- Determine also top k per cell -sensitive cells
- Table redesign possible without going back to
microdata - Uses procedures for secondary cell suppression
using state-of-the optimisation algorithms (CPR) - Prepared for linked tables
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t-ARGUS
- Data fixed format ASCII
- Meta data
- Variable name
- Start. position
- Field length
- Status
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t-ARGUS
- Apply global recoding
- Protect file with secondary suppression
- Rounding
- Safe table as ASCII or .WK1(plus report)
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t-ARGUS
- Version 2.0 final SDC-version
- requires commercial OR-solver(Xpress by Dash,
UK, 600 GBP)
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Future / CASC
- Computational Aspects of Statistical
Confidentiality - New European project-proposal(2000-2002)
- Extending ARGUS
- New research
- Additional joint USA/EU-project?
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CASC-m
- Concentration on business/economic data
- microaggregation
- PRAM
- Noise-addition/ masking
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CASC-t
- Hierarchical tables
- Linked tables
- Optimal solution vz. heuristics
- Different input formats
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CASC-team
- Statistics Netherlands
- Istat (Italy)
- ONS, Univ. Southampton, Manchester, London,
Plymouth (UK) - Bundesambt, IAB (Germany)
- Stat. Catalunya, Univ Tenerife (Spain)
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Contact
- Anco Hundepool
- Statistics Netherlands
- PO box 4000
- 2200 JM Voorburg
- The Netherlands
- email ahnl_at_krypton.vb.cbs.nl
- fax 31 70 3375990
- phone 31 70 3375038
