This is DDI-Codebook version 2.6 submitted for final review 2025-12-15.

THIS IS A REVISION of 2.5.1 and is backward compatible with 2.5 (a valid instance of DDI-Codebook 2.5 will 
validate against version 2.6).

The current publication includes the schemas, field-level documentation publication in 
HTML, and change documentation. Additional documentation on the use of DDI-Codebook 2.6 are published
as separate documents on the DDIAlliance.org product page for DDI-Codebook.

The continued development of DDI-Codebook reflects the work of the
committees and individuals who developed DDI versions 1.0 - 2.5 as well as the collective
ideas, needs, and work of the Scientific Community of the DDI Alliance. 

We would like to thank the following member organizations which have
supported the DDI Alliance in their development of DDI version 2.6:

    Aristotle Cloud Services
    Australian Bureau of Statistics (ABS)
    Australian Data Archive (ADA)
    Blaise - Statistics Netherlands
    University of California, Berkeley -- Computer-Assisted Survey Methods Program and UCDATA, USA
    Center for Socio-Political Data (CDSP), Sciences P0
    Central Statistics Office (Ireland)
    Centre for Longitudinal Studies, Institute of Education University of London (Associate Member)
    Centro De Investigaciones Sociologicas (CIS), Spain
    CLOSER, UCL Institute of Education
    CODATA, Committee on Data of the International Science Council
    Colectica
    Consortium of Social Science Data Archives (CESSDA)
    CONSTANCES Cohort
    Cornell Center for Social Sciences
    Cornell University (CISER)
    Danish Data Archive
    Data Archiving and Networked Services (DANS), The Netherlands
    Data Unchained, LLC
    DataVerse
    Finnish Social Science Data Archive
    France Cohortes/FReSH
    French Institute for Demographic Studies (INED)
    German Socio-Economic Panel Study (SOEP)
    GESIS - Leibniz Institute for the Social Sciences
    HiveWorx
    Institute for Qualitative Social Science (IQSS) at Harvard University
    Institute for the Study of Labor (IZA), Germany
    Institute for Social and Economic Research (ISER)
    International Association of Social Science Information Service and Technology (IASSIST)
    International Federation of Data Organizations (IFDO)
    Inter-university Consortium for Political and Social Research (ICPSR), USA
    Making Sense
    Massachusetts Institute of Technology (MIT), USA
    Metadata Technologies, NA
    mStats DS - Data Science and Statistical Software
    National Institute of Statistics and Economic Studies (INSEE)
    Nooro Online Research
    Norwegian Social Science Data Service (NSD)
    Open Data Foundation, USA
    Princeton University, USA
    Qualiservice
    Research Data Centre of the German Federal Employment Agency, Institute for Employment Research (IAB)
    Roper Center for Public Opinion Research, USA
    Sikt - Norwegian Agency for Shared Services in Education and Research
    Stanford University, USA
    Statistics Canada
    Statistics Estonia
    Statistics New Zealand
    Survey Research Operations, University of Michigan
    Swedish National Data Service (SND)
    Swedish Social Science Data Service (SSD)
    Swiss Data Archive for the Social Sciences (SIDOS)
    Swiss Foundation for Research in Social Sciences (FORS)
    TBA21 Group
    University of Alberta, Canada
    University of Applied Sciences of the Grisons (FHGR)
    University of Guelph, Canada
    University of Kansas, Institute for Policy and Social Research (IPSR)
    University of Minnesota, Minnesota Population Center (MPC), USA
    University of Toronto Scholars Portal
    United Kingdom Data Archive
    University of Washington, Center for Studies in Demography & Ecology (CSDE), USA
    University of Wisconsin Institute on Aging - MIDUS study
    United States Bureau of Labor Statistics (Associate Member)
    Wisconsin Longitudinal Study
    World Bank, Development Data Group (DECDG)


DDI 2.6 XML Schema is released under the terms of the Creative Commons BY 4.0 (International).
Details see the file license.txt.