1. Universitat Pompeu Fabra, Barcelona, Spain
2. Luxemburg Institute of Socio-economic Research (LISER) and Luxembourg Income Study (LIS), Luxembourg; Research Institute Economics of Inequality, Vienna University of Economics and Business, Austria
3. German Centre for Higher Education Research and Science Studies (DZHW), Germany
4. Federal Institute for Vocational Education and Training (BIBB), Germany; Maastricht University, Netherlands