Documenting, Maintaining, and Sharing 12.09.2018 Documenting, Maintaining, and Sharing Standard Variables with DDI Version 3.0: the ISCO example Joachim Wackerow GESIS-ZUMA German Social Science Infrastructure Services / Centre for Survey Research and Methodology IASSIST 2007, May 16 Soztag03 d

Outline ISCO ISCO in DDI 3 DDI 3 as Metadata Repository Description Revisions / Versions ISCO in DDI 3 Variable Description Comparison of Variables Standalone Resource Package DDI 3 as Metadata Repository

Intention of presentation 12.09.2018 Intention of presentation ISCO as an example to show reuse of metadata by the means of DDI 3.0 Not a presentation on the content of the ISCO classification Focus on documenting standard variables in standalone resources Report on first experiences with DDI 3.0 - ISCO is just used as an example to show some features of the new DDI Similar to the previous presentation it is an report on first experiences with the new DDI Soztag03 d

ISCO Description International Standard Classification of Occupations 12.09.2018 ISCO Description International Standard Classification of Occupations Maintained by the International Labour Organization (ILO) ISCO is a tool for organizing jobs into a clearly defined set of groups according to the tasks and duties undertaken in the job. ISCO organizes occupations in a hierarchical framework. At the lowest level is the unit of classification - a job - which is defined as a set of tasks or duties designed to be executed by one person. Jobs are grouped into occupations according to the degree of similarity in their constituent tasks and duties. ISCO is defined in four levels of aggregation, for example ISCO-88(COM) consists of: 10 major groups 28 sub-major groups (subdivisions of major groups) 116 minor groups (subdivisions of sub-major groups) 390 unit groups (subdivisions of minor groups) Description citation from ILO Soztag03 d

ISCO Example: Major Group 6 Skilled agricultural and fishery workers 12.09.2018 ISCO Example: Major Group 6 Skilled agricultural and fishery workers 61 Skilled agricultural and fishery workers 611 Market gardeners and crop growers 6111 Field crop and vegetable growers 6112 Gardeners, horticultural and nursery growers 612 Animal producers and related workers 6121 Dairy and livestock producers 6122 Poultry producers 6129 Animal producers and related workers not elsewhere classified 613 Crop and animal producers 6130 Crop and animal producers Clipping of major group 6 Here only one category exists on the sub-major group level. This is the same as on the major group level. Minor group with two unit groups. Two other minor groups. Soztag03 d

Revisions / Versions of ISCO 1958, 1968, 1988 (current revision), 2008 (draft) Versions with minor differences exist, for example: ISCO-88(COM) for the European Union (Eurostat) ISCO-88(CIS) for the Commonwealth of Independent States (CIS Statistical Committee) ISCO-88(OCWM) Occupational Classification of Workers in Migration under ISCO-88 of ILO/UNDP Asian Regional Programme on International Labour Migration (ILO, Bangkok, 1992) Country-specific variants Country-specific classifications which can be converted into ISCO

Examples for ISCO usage in major studies 12.09.2018 Examples for ISCO usage in major studies Direct usage ESS - European Social Survey ISSP - International Social Survey Programme The Eurobarometer Survey Series SOEP – German Socio-Economic Panel Study Conversion from other occupation classification GSS (US General Social Survey) - ISCO-68, converted from 1970 U.S. Census Classification of Occupations and Industries German Microcensus – ISCO-88(COM), converted from classification KldB92 German panel study from the presentation before uses the Eurpean Union variant of ISCO-88 Soztag03 d

Standard Variables ISCO as a standard variable facilitates the usage of an occupation variable in multiple studies Comparison of studies is one of the major goals of standard variables By using standard variables within an organization or across a group of organizations central documentation and maintenance of these variables is improved Standard variables can be maintained in a variable repository The variable repository should be processable by applications for better exploitation DDI 3 provides the metadata structure for a machine-actionable variable repository

DDI: Metadata Structure for Variable Repositories 12.09.2018 DDI: Metadata Structure for Variable Repositories Different parts of a variable are documented in different schemes. This enables reuse of these parts. Central description of a variable in a variable scheme Variable scheme ISCO-88(COM) … other variables Category codes are listed in a code scheme which can be referenced by a one or more variables Example: Occupation of respondent, occupation of spouse of respondent Schemes are basically a list of items “variable explosion”, term from Wendy Thomas, sounds like demolition, but it is really the reverse - Description of categories: labels, missing categories Soztag03 d

DDI: ISCO Hierarchy of Codes Example: Major Group 6 61 Skilled agricultural and fishery workers 611 Market gardeners and crop growers 6111 Field crop and vegetable growers 6112 Gardeners, horticultural and nursery growers 612 Animal producers and related workers 6121 Dairy and livestock producers 6122 Poultry producers 6129 Animal producers and related workers not elsewhere classified 613 Crop and animal producers 6130 Crop and animal producers

DDI: ISCO Hierarchy of Codes Example: Major Group 6 12.09.2018 DDI: ISCO Hierarchy of Codes Example: Major Group 6 61 611 6111 6112 612 6121 6122 6129 613 6130 This forms a regular hierarchy. All codes on a lower level form one code of a higher level. Achieved by nesting. Soztag03 d

DDI: Metadata Structure for Variable Repositories 12.09.2018 DDI: Metadata Structure for Variable Repositories Different parts of a variable are documented in different schemes. This enables reuse of these parts. Central description of variable in a variable scheme Codes for categories are listed in a code scheme which can be referenced by a one or more variables Description of categories in a category scheme which can be referenced by one or more code schemes Schemes are basically a list of items “variable explosion”, term from Wendy Thomas, sounds like demolition, but it is really the reverse - Description of categories: labels, missing categories Soztag03 d

DDI: ISCO Hierarchy of Codes Example: Major Group 6 61 Skilled agricultural and fishery workers 611 Market gardeners and crop growers 6111 Field crop and vegetable growers 6112 Gardeners, horticultural and nursery growers 612 Animal producers and related workers 6121 Dairy and livestock producers 6122 Poultry producers 6129 Animal producers and related workers not elsewhere classified 613 Crop and animal producers 6130 Crop and animal producers

DDI: ISCO Hierarchy of Codes Example: Major Group 6 Skilled agricultural and fishery workers Market gardeners and crop growers Field crop and vegetable growers Gardeners, horticultural and nursery growers Animal producers and related workers Dairy and livestock producers Poultry producers Animal producers and related workers not elsewhere classified Crop and animal producers

DDI: Metadata Structure for Variable Repositories 12.09.2018 DDI: Metadata Structure for Variable Repositories Different parts of a variable are documented in different schemes. This enables reuse of these parts. Central description of variable in a variable scheme Codes for categories are listed in a code scheme which can be referenced by a one or more variables Description of categories in a category scheme which can be referenced by one or more code schemes Multiple languages can be used in the documentation, important for labels Schemes are basically a list of items “variable explosion”, term from Wendy Thomas, sounds like demolition, but it is really the reverse - Description of categories: labels, missing categories in a list Additional language would not result in a new variable, it would be documented parallet to the first language. Soztag03 d

DDI: Category Example Multiple Languages <l:Category> <r:Identification> <r:ID>Level2Category61</r:ID> </r:Identification> <r:Label xml:lang ="en">Skilled agricultural and fishery workers</r:Label> <r:Label xml:lang="de">Fachkräfte in der Landwirtschaft und Fischerei</r:Label> <r:Label xml:lang ="fr">Agriculteurs et ouvriers qualifiés de l'agriculture et de la pêche</r:Label> </l:Category>

12.09.2018 DDI: Concepts A variable represents a theoretical concept about the reality, for ISCO the concept is “Work”. Concepts are described in DDI 3 in a concept scheme. Similar variables can point to the same concept. Additionally the concepts can be organized in concept groups. The concept for ISCO is more precisely “Paid work”. “Work” is the more general concept which can comprehend other types of work. Soztag03 d

DDI: Minor changes of variables New revisions of variables 12.09.2018 DDI: Minor changes of variables New revisions of variables Variables, code and category schemes undergo changes, i.e. error correction. This change can be documented in a new version of the same DDI scheme. The responsible agency can be documented. Both version and maintaining agency are part of the global unique identifier of an item urn:ddi:3_0:CodeScheme:gesis.org:lp:2_0.ISCO88:1_0 Additional documentation: version date, version responsibility, version rationale Scheme or item like category If an application doesn’t use a specific version, the version with the highest number will be used. Example of minor change: different wording of a label Category would get new a new version number and also the containing category scheme. URN - Uniform Resource Name Soztag03 d

DDI: Minor changes of variables New revisions of variables 12.09.2018 DDI: Minor changes of variables New revisions of variables Variables, code and category schemes undergo changes, i.e. error correction. This change can be documented in a new version of the same DDI scheme. For ISCO a new revision is published every 10 years. Different versions exist for example for ISCO-88. Most of these versions are still used. So they can be documented in DDI as separate variables, not as separate versions. If an application doesn’t use a specific version, the version with the highest number will be used. Example of minor change: different wording of a label Category would get new a new version number and also the containing category scheme. URN - Uniform Resource Name Soztag03 d

DDI: Relationship between Similar Variables 12.09.2018 DDI: Relationship between Similar Variables The relationship between these similar variables can be documented in comparison tables ISCO-88 ISCO-08 Category 6112 6113 Tree and shrub crop growers 6114 6115 Mixed crop growers Derived categories can be described in the category scheme 6123 and 6124 (ISCO-88) to 6124 (ISCO-08) Apiarists and sericulturists Human-readable description Derivation command of the used program / package The type of relationship on code or category level can be expressed. A machine-actionable description of the comparison quality seems to be missing. Soztag03 d

DDI: Resource Package Resource Package … Concept „Paid Work“ Concept Group „Work“ Comparison Table Codes Ref. to ISCO-88 Ref. to 6114 ISCO-08 Ref. to 6115 Variable Scheme Variable „ISCO-68“ Variable „ISCO-88“ Code 6114 Code Scheme „ISCO-88“ … Category „Mixed crop grwr” Category Scheme „ISCO-88“ …

DDI: Resource Package as Reusable Set of Metadata 12.09.2018 DDI: Resource Package as Reusable Set of Metadata Resource packages can be used by multiple studies documented in DDI. The same metadata is reused and this implies potential comparability European Social Survey Variable Reference Resource Package Concept „Work“ Code Scheme „ISCO-88“ Variable „ISCO-88 “ Category Scheme „ISCO-88“ Eurobarometer Variable Reference Items in local or remote resource packages can be referenced by an global unique identifier. Soztag03 d

DDI: Resource Package as Reusable Set of Metadata 12.09.2018 DDI: Resource Package as Reusable Set of Metadata Schemes in resource packages can be used in multiple ways. Study Variable „Occupation of Spouse“ Resource Package Concept „Work“ Code Scheme „ISCO-88“ Variable „ISCO-88 “ Category Scheme „ISCO-88“ Variable „Occupation of Father“ Items in local or remote resource packages can be referenced by an global unique identifier. Soztag03 d

DDI: Resource Package Metadata Repository 12.09.2018 DDI: Resource Package Metadata Repository Concepts, variables, code schemes, and category schemes as a whole create a metadata registry DDI 3 borrowed ideas from the standard ISO/IEC 11179 (description of the structure for metadata registries on an abstract level) A metadata registry (for offline or online usage) requires an application in addition to the metadata structure Full advantage of a metadata registry by a search front end and by web services for programs Variable search by web page. Integration of reusable metadata in other application. Soztag03 d

DDI and ISO/IEC 11179 Data Element Value Domain Permissible Value 12.09.2018 DDI and ISO/IEC 11179 Data Element Value Domain Permissible Value Diagram thanks to Chris Nelson. This core part of DDI maps directly to equivalent constructs in ISO/IEC 11179. In ISO/IEC 11179 different terms are used. Data Element Concept Conceptual Domain Value Meaning Soztag03 d

Conclusion Advantages in usage of DDI metadata repositories 12.09.2018 Conclusion Advantages in usage of DDI metadata repositories Easy exchange of the documentation of standard variables Enabling metadata mining for finding potential comparable studies Support for survey designers, when questionnaires are included Can support the process of establishing a standard variable Basis of metadata registry application Requirements / Limitations Requires often a well established standard variable like ISCO Acting in a controlled environment is required, quality assurance Trusted relationship to maintaining organization is necessary, especially when using automated access like a web service Large variety of “standard variables” for one concept can cause problems Using DDI 3 resource packages is one step into the direction of “Building global knowledge communities with open metadata” Advantages Support for survey designers, when metadata repositories are expanded by the related questionnaires Requirements / Limitatations (more general) Controled way can be an advantage within an organization local modifications are often made to improve the accuracy of a measured subject, but at the same time the standardization and the implied comparison potential can loose on quality Machine-actionable qualifier for comparison required Final remark Soztag03 d

Thank you for your attention Basic DDI example on ISCO-88(COM) available at DDI 3.0 page: http://www.ddialliance.org/ddi3/ joachim.wackerow@gesis.org African Scops Owl