Jürgen H. P. Hoffmeyer-Zlotnik is professor at the Institute of Political Science at Justus Liebig-University in Gießen, Germany, and former head of the Knowledge Transfer Unit at GESIS – Leibniz Institute for the Social Sciences in Mannheim, Germany. Until 2011, he coordinated and organized the GESIS workshop and seminar program as well as the GESIS Summer School on Survey Methodology. His main research interests are standardization and harmonization of demographic and socio-economic background variables for national and international comparison and cross-country comparative survey research. Dr. Uwe Warner was senior researcher at CEPS/”The International Network for Studies in Technology, Environment, Alternatives, Development (INSTEAD)”, Luxembourg until 2014. His main research topics are cross-national comparative survey research, poverty, income and well-being, and socio-demographic background variables. Currently, he is visiting researcher atthe Center of Methods in Social Sciences, Georg August-University Göttingen, Germany.