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

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

Introduction

Cell suppressionStand alone tableHierarchically linked tablesSubset of generally linked tables

Hierarchically linkedDifferent detail of same hierarchy

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Introduction

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Introduction

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

Introduction

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Introduction

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Hierarchies

Need way to define set of linked tables

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Hierarchies as trees

S A A1

B2 B21

C2 C21

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Pure sub hierarchies

G H1 H2 H3

S A A1

B2 B21

C2 C21

H1 � G H2 6� G H3 6� G

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Pure sub hierarchies

G H1 H2 H3

S A A1

B2 B21

C2 C21

H1 � G H2 6� G H3 6� G

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Covering hierarchies

G covers the set of hierarchies (H1, . . . ,HK )

G is the smallest hierarchy with

Hi � G ∀i = 1, . . . , K

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

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

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

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

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

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

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

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

However:interior A× B × C is unique!Any unsafe cell in interior is implicitly disclosed!

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Example of problem

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!

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

Example of problem

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!

Contents

Introduction

HierarchiesTrees

Pure sub

Covering

Linking

ProblemsExample

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

Similarly: suppression pattern can be broken

Problem may also occur in current situationUsed hierarchy not complete detail

Thank you.

Cell suppression in a special class of linked tables€¦ · Notes Introduction Cell suppression...

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