Alessandra Capobianchi and Luisa Franconi Istat - Division for Information Technology and Methodology - Italy Ntts 2009 Brussel Febbruary 2009 Cell suppression in linked tables from structural business statistics using Tau Argus 3.3.0: a conceptual framework

What are linked tables? NTTS 2009 Brussel Febbruary 2009 Tables presenting data on the same response variable sharing some categories of at least one explanatory variable are said Linked tables. Such esplanatory variable is called linked variable.

Motivation NTTS 2009 Brussel Febbruary EUROSTAT Since now Eurostat was in charge of protecting tables requested by SBS Regulations and performed a global confidentiality treatment. From 2008 Eurostat will not treat the confidentiality of the Sbs tables and each NIS has to take care on his own of such protection process - SBS tables Community Structural Business Statistics (SBS) are a set of hierarchical linked tables with spanning variable that present different levels of the hierarchy in different tables - Software Tau-argus version available at the website of the Essnet project Currently it doesnt deal with hierarchical linked tables that present different levels of the hierarchy. -NEED To develop a scheme to cope with such problem

Community Structural Business Statistics (SBS) are collected within the framework of Council Regulation (EC, EURATOM) No. 58/97 of December Definitions and table breakdowns are specified in a series of Commission and Council Regulations. We focus our attention on the first four annexes covering the 'business economy (Annex1), industry (Annex2), distributive trades (Annex3) and construction (Annex4). Aim- Achive the protection of the Structural Business Statistics deriving from such annexes Community Structural Business Statistics NTTS 2009 Brussel Febbruary 2009

Conceptual scheme NTTS 2009 Brussel Febbruary 2009 The protection process of the SBS linked tables can be divided into three steps: 1.Translate the legal framework into a set of tables create a set of tables for Argus 2. Analyse the links between tables establish an order in the protection of the tables 3. Apply Tau-Argus to each table according to the order previously established maintain coherences in the suppression pattern

The tables we focus on are those related to: annual enterprise statistics (at 4 digit Nace code) annual enterprise statistics (at 3 digit Nace code) by size classes annual enterprise statistics (at 2 digit Nace code) by region (NUTS2) The main statistical unit is the enterprise even if some statistics are produced also for KAU and for local unit Enterprise= the smallest combination of legal units that is an organisational unit producing goods or services Kau= kind-of-activity unit that groups all the parts of an enterprise contributing to the performance of an activity at the class level (four digits) of NACE Local Unit= an enterprise or part thereof (e.g. a workshop, factory, warehouse, office, mine or depot) situated in a geographically identified place 1.Traslation NTTS 2009 Brussel Febbruary 2009

However, such general scheme comprising three types of tables presents some relevant differences: the first table is replicated with KAU as response unit in the second table the variable size class presents two different classifications for different sectors (C-F and G-K); for sector G: the regional table is released at NACE 3 level instead of NACE 2; only for this sector there is the additional table relating to NACE 3 by turnover in classes. 1.Translation : some peculiarities NTTS 2009 Brussel Febbruary 2009

The tables considered in the general scheme need to be split into several tables that are homogeneous in the level of the classifying variables and response unit. 1.Translation: the set of tables NTTS 2009 Brussel Febbruary 2009 Definition of spanning variables for each table to be processed by Argus in order to fulfil SBS regulations Tables processed by Argus Classifying variable Response unit Annex Tab1.1NACE 4EnterpriseAnnex 1A, Annex 2A, Annex 4A and Annex 3B Tab1.2NACE 4(KAU)Annex 2E and Annex 4E Tab2.1NACE 3 by size class1 EnterpriseAnnex 2D and Annex 4D Tab2.2NACE 3 by size class2 EnterpriseAnnex 3C and Annex 1B Tab2.3NACE 3 by NUTS-2local unitAnnex 3E Tab2.4NACE 3 by Turnover in classes EnterpriseAnnex 3C Tab3.1NACE 2 by NUTS-2local unitAnnex 1C, Annex 2F and Annex 4F

The analysis of the levels of the hierarchy of the linked variable implies the definition of a scheme of relationships that provides the order of the processing of the tables from the most detailed level of the hierarchy to the most aggregated. Thats because more detailed cells of the table will contribute to the construction of marginal cells in other tables that present a lower level of the hierarchy of the linked variable. Common cells need to present a coherent suppression pattern. 2. Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

The most detailed tables is Tab1.1. That table is relative to all enterprises classified according to classes of NACE classification in 4 digit codes. That table will be called the starting table. 2. Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

The next table to be processed should present the hierarchical level of the linked variable immediately higher than the starting table. In SBS Community statistics there are two tables: Tab2.1 and Tab2.2: - present 3 digit NACE code as classifying variable. - are related to different sectors of the economy and no link exist between the two tables - present two different classifications of the variable size class relative to different sectors of NACE code 2. Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

2. Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

The next level of the hierarchy of the linked variable is 2 digit NACE code In SBS Community statistics there is theTab3.1 that present this hierarchical level and is related to sectors C to K excluding G of the NACE classification. -Tab3.1 presents marginal derived from tab2.1 and tab2.2 for sectors C to K excluding G -The response unit are different but enterprises either coincide with local units or comprise of more than one local unit 2. Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

2. Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

Some relevant differences are presented for the sector G. -The regional table is released at NACE 3 level instead of NACE 2; Tab2.3 and is linked only to tab2.2. -There is an additional table released at NACE 3 level by turnover in classes; Tab2.4 linked to tab3.2 Also for sectors C-F the table at NACE 4 level is presented not only for enterprises but also for KAU; Tab1.2. The tables tab1.1 and tab1.2 coincide almost perfectly so it has been decided to apply Tab1.1 pattern of suppression to Tab Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

2. Analysis of the Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

The order generated by the analysis of the links between the tables as described in the previous scheme aims to identify common cells in subsequent tables. Common cells need to present a coherent suppression pattern. Tau-Argus software allows to fix a setting of a priory information for cells selected by the user. Such flexibility of the software can be used to impose coherent suppression patterns to a set of tables 3. Protection phase: a priory information NTTS 2009 Brussel Febbruary 2009

This A priori information is organised in an history file. In the history file the user, before the protection phase, can assign to predetermined cells of the table, one of the following protection status. 3. Protection phase: a priory information NTTS 2009 Brussel Febbruary 2009 Alphanumeric code MeaningAction to be taken by Argus UUnsafeThe cell has to be protected. SSafeThe cell is not at risk; it can be used as secondary suppression. PProtectedThe cell cannot to be used as secondary suppression.

The protection process using secondary cell suppression starts from: Tab1.1; the most detailed table. This table is protected by Argus according to the rules established by the Member State. In order to communicate to Argus the information related to the protection of this starting table we ask the software to save the status information relative to each single cell of the protected tab1.1. Five different output status are allowed by Tau-Argus; 3.Protection of a Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

The second step is to protect the second table of the scheme tab2.1 All the suppression applied to the previous table tab1.1 to the common marginal cells, have to be replicated in the current table tab2.1 This will be done by creating an history file for the current table (tab2.1) containing a priori information that will impose to Argus the constraints stemming from the protection of the previous table (tab1.1). Different types of constraints may arise for each of the common cell. 3.Protection of a Set of Linked Tables NTTS 2009 Brussel Febbruary 2009

3.Protection of a Set of Linked Tables NTTS 2009 Brussel Febbruary 2009 Output status of the common cell in the previous table MeaningA priori information of the common cell of the current table Action taken by Argus 1SafePThis cell will not be selected as secondary suppression 5Unsafe Argus will recognise a primary suppression 11Secondary suppression USet to manually unsafe in the current table i.e. to be protected 14Missing value 9Manually unsafe USet to manually unsafe in the current table i.e. cell to be protected 10Manually safePThis cell will not be selected as secondary suppression Output status in the previous table, meaning and corresponding status to be applied in the a priori information for the current table.

3.Process is applied following the relationship scheme NTTS 2009 Brussel Febbruary 2009 Tab1.1 Apply Tau Argus Create.saf file Convert information contained in the.saf file into a priori information for tab2.1 and tab2.2 Select common cells (tab1.1 with tab2.1; tab1.1 and tab2.2) and create the History files (H2.1, H2.2) Tab2.1 Apply History file H2.1 Apply Tau Argus Create.saf file Convert information contained in the.saf file into a priori information for tab3.1 Select common cells (tab2.1 with tab3.1) and create the History file (H3.1_1 ) Tab2.2 Apply History file H2.2 Apply Tau Argus Create.saf file Convert information contained in the.saf file into a priori information for tab3.1 Select common cells (tab2.2 with tab3.1) and create the History file (H3.1_2 ) Tab3.1 Apply History files H3.1_1 and H3.1_2 Apply Tau Argus Create.saf file

Conclusions and Further Work Conclusion We describe a process to protect linked hierarchical tables from SBS using Tau-Argus We have successfully aaplied the process to the Italian sample of SBS Further work With the entry into force of the new SBS regulation pertaining changes due to the adoption of the new classification of economic activities, NACE rev.2, more work need to be done. Study protection pattern harmonised between subsequent years need to be carefully tuned so that coherence is maintained not only within a year but also for successive years.