Leveraging the DDI Model for Linked Statistical Data in the Social, Behavioural, and Economic Sciences DC Thomas Bosch GESIS – Leibniz Institute for the Social Sciences, Germany Richard Cyganiak Digital Enterprise Research Institute, Ireland Joachim Wackerow GESIS – Leibniz Institute for the Social Sciences, Germany Benjamin Zapilko GESIS – Leibniz Institute for the Social Sciences, Germany

2 Agenda

DDI (Data Documentation Initiative) Established international standard for the documentation and management of data from the social, behavioral, and economic sciences Data model for statistical data Supports the entire research data lifecycle Focus on microdata Structured high quality metadata enable secondary analysis without the need to contact the primary researcher Enables the re-use of metadata of existing studies for designing new studies Currently specified in XML Schema 3 What is DDI?

DDI subset of the most important DDI elements Use cases Experts in the statistics domain formulated use cases which are seen as most significant to solve frequent problems Most important use case: discover microdata connected with multiple studies Leverage existing DDI-XML docs to DDI-RDF automatically Direct mapping Generic mapping (Bosch and Mathiak, 2011) 4 How was the DDI Ontology developed?

Currently no such ontology available To increase visibility of data holdings using mainstream Web technologies To open DDI to the Linked Data community To process DDI-RDF by RDF tools To link DDI-RDF to other RDF data To better identify opportunities for merging datasets To enable inferencing To research microdata within the LOD cloud 5 Why DDI as Linked Data?

Dublin Core Metadata Element Set, Version 1.1 DCMI Metadata Terms SKOS SDMX  RDF Data Cube Vocabulary ISO/IEC ISO What other metadata standards vocabularies are used?

Which studies are connected with a specific coverage consisting of the 3 dimensions: time, country, and subject? What questions with a specific question text are contained in the study questionnaire? What questions are connected with a concept with a specific label? What questions are combined with a variable with an associated coverage consisting of the 3 dimensions time, country, and subject? What concepts are linked to particular variables or questions? What representation does a specific variable have? What codes and what categories are part of this representation? What variable label does a variable with a particular variable name have? What‘s the maximum value of a certain variable? What are the absolute and relative frequencies of a specific code? What data files contain the entire dataset? 7 Discovery Use Case

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9 study | coverage

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11 instrument | question | concept

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values | value labels 14

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17 variable | descriptive statistics

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20 logical dataset | dataset | data file

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conceptual model 23

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Acknowledgements Archana Bidargaddi (NSD - Norwegian Social Science Data Services, Norway) Franck Cotton (INSEE - Institut National de la Statistique et des Études Économiques, France) Richard Cyganiak (DERI - Digital Enterprise Research Institute, Ireland) Daniel Gilman (BLS - Bureau of Labor Statistics, USA) Marcel Hebing (SOEP - German Socio-Economic Panel Study, Germany) Larry Hoyle (University of Kansas, USA) Jannik Jensen (DDA - Danish Data Archive, Denmark) Stefan Kramer (CISER - Cornell Institute for Social and Economic Research, USA) Amber Leahey (Scholars Portal Project - University of Toronto, Canada) Abdul Rahim (Metadata Technologies Inc., USA) John Shepherdson (UK Data Archive, UK) Dan Smith (Algenta Technologies Inc., USA) Humphrey Southall (Department of Geography, UK Portsmouth University, UK) Wendy Thomas (MPC - Minnesota Population Center, USA) Johanna Vompras (University Bielefeld Library, Germany) 25

Thank you for you attention! 26