Hierarchically Focused Guardbanding: An Adaptive Approach ...
Cell suppression in a special class of linked tables€¦ · Notes Introduction Cell suppression...
Transcript of Cell suppression in a special class of linked tables€¦ · Notes Introduction Cell suppression...
Cell suppression in a special class oflinked tables
Peter-Paul de Wolf
Statistics Netherlands
December 17, 2007Manchester, Great Brittain
Contents
Introduction
HierarchiesTreesPure subCoveringLinking
ProblemsExampleNotes
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Introduction
Cell suppressionStand alone tableHierarchically linked tables
Subset of generally linked tablesHierarchically linkedDifferent detail of same hierarchy
5-digit NACE code × high level region2-digit NACE code × detailed region5-digit NACE code × detailed region
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Introduction
Cell suppressionStand alone tableHierarchically linked tablesSubset of generally linked tables
Hierarchically linkedDifferent detail of same hierarchy
5-digit NACE code × high level region2-digit NACE code × detailed region5-digit NACE code × detailed region
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Introduction
Cell suppressionStand alone tableHierarchically linked tablesSubset of generally linked tables
Hierarchically linkedDifferent detail of same hierarchy
5-digit NACE code × high level region2-digit NACE code × detailed region5-digit NACE code × detailed region
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Introduction
Cell suppressionStand alone tableHierarchically linked tablesSubset of generally linked tables
Hierarchically linkedDifferent detail of same hierarchy
5-digit NACE code × high level region2-digit NACE code × detailed region
5-digit NACE code × detailed region
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Introduction
Cell suppressionStand alone tableHierarchically linked tablesSubset of generally linked tables
Hierarchically linkedDifferent detail of same hierarchy
5-digit NACE code × high level region2-digit NACE code × detailed region5-digit NACE code × detailed region
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Introduction
Cell suppressionStand alone tableHierarchically linked tablesSubset of generally linked tables
Hierarchically linkedDifferent detail of same hierarchy
5-digit NACE code × high level region2-digit NACE code × detailed region5-digit NACE code × detailed region
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Hierarchies
Need way to define set of linked tables
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Hierarchies as trees
S A A1
A2
B B1
B2 B21
B22
C C1
C2 C21
C22
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Pure sub hierarchies
G H1 H2 H3
S A A1
A2
B B1
B2 B21
B22
C C1
C2 C21
C22
S A
B
C C1
C2
S A1
A2
B1
B2
C1
C2
S A
B
H1 � G H2 6� G H3 6� G
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Pure sub hierarchies
G H1 H2 H3
S A A1
A2
B B1
B2 B21
B22
C C1
C2 C21
C22
S A
B
C C1
C2
S A1
A2
B1
B2
C1
C2
S A
B
H1 � G H2 6� G H3 6� G
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Covering hierarchies
G covers the set of hierarchies (H1, . . . ,HK )
if
G is the smallest hierarchy with
Hi � G ∀i = 1, . . . , K
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Defining linked tables
User specifies N tables to be protectedTables can be hierarchical
All hierarchies of same variable should be coverable!
Tables have M different spanning variablesDefine M-dimensional table with hierarchies coveringuser defined hierarchiesUse modular approach, disregarding subtables not inuser set of tables
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Defining linked tables
User specifies N tables to be protectedTables can be hierarchical
All hierarchies of same variable should be coverable!
Tables have M different spanning variablesDefine M-dimensional table with hierarchies coveringuser defined hierarchiesUse modular approach, disregarding subtables not inuser set of tables
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Defining linked tables
User specifies N tables to be protectedTables can be hierarchicalAll hierarchies of same variable should be coverable!Tables have M different spanning variablesDefine M-dimensional table with hierarchies coveringuser defined hierarchiesUse modular approach, disregarding subtables not inuser set of tables
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Defining linked tables
User specifies N tables to be protectedTables can be hierarchicalAll hierarchies of same variable should be coverable!Tables have M different spanning variablesDefine M-dimensional table with hierarchies coveringuser defined hierarchiesUse modular approach, disregarding subtables not inuser set of tables
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Defining linked tables
User specifies N tables to be protectedTables can be hierarchicalAll hierarchies of same variable should be coverable!Tables have M different spanning variablesDefine M-dimensional table with hierarchies coveringuser defined hierarchiesUse modular approach, disregarding subtables not inuser set of tables
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Defining linked tables
User specifies N tables to be protectedTables can be hierarchicalAll hierarchies of same variable should be coverable!Tables have M different spanning variablesDefine M-dimensional table with hierarchies coveringuser defined hierarchiesUse modular approach, disregarding subtables not inuser set of tables
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Problems
Implicitly defined structure is not protected explicitly
Set of tables completely determines interior of higherdimensional table
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Problems
Implicitly defined structure is not protected explicitly
Set of tables completely determines interior of higherdimensional table
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Example of problem
B1 B2 B3 Total C1 C2 C3 TotalA1 30 150 70 250 A1 140 50 60 250A2 270 110 255 635 A2 85 210 340 635
Total 300 260 325 885 Total 225 260 400 885
Safe! Safe!
C1 C2 C3 TotalB1 110 90 100 300B2 40 50 170 260B3 75 120 130 325
Total 225 260 400 885
Safe!
However:interior A× B × C is unique!Any unsafe cell in interior is implicitly disclosed!
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Example of problem
B1 B2 B3 Total C1 C2 C3 TotalA1 30 150 70 250 A1 140 50 60 250A2 270 110 255 635 A2 85 210 340 635
Total 300 260 325 885 Total 225 260 400 885Safe! Safe!
C1 C2 C3 TotalB1 110 90 100 300B2 40 50 170 260B3 75 120 130 325
Total 225 260 400 885Safe!
However:interior A× B × C is unique!Any unsafe cell in interior is implicitly disclosed!
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Example of problem
B1 B2 B3 Total C1 C2 C3 TotalA1 30 150 70 250 A1 140 50 60 250A2 270 110 255 635 A2 85 210 340 635
Total 300 260 325 885 Total 225 260 400 885Safe! Safe!
C1 C2 C3 TotalB1 110 90 100 300B2 40 50 170 260B3 75 120 130 325
Total 225 260 400 885Safe!
However:interior A× B × C is unique!Any unsafe cell in interior is implicitly disclosed!
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Similarly: suppression pattern can be broken
Problem may also occur in current situationUsed hierarchy not complete detail
Contents
Introduction
HierarchiesTrees
Pure sub
Covering
Linking
ProblemsExample
Notes
Similarly: suppression pattern can be broken
Problem may also occur in current situationUsed hierarchy not complete detail
Thank you.