Franciszek Sztabiński is Professor of Sociology at the Institute of Philosophy and Sociology at the Polish Academy of Sciences. His main research interests include survey methodology, in particular issues of mode effects and mixed mode data collection.Henryk Domański is Professor of Sociology at the Institute of Philosophy and Sociology at the Polish Academy of Sciences. His main fields of interest are social stratification and mobility, and methodology of social research. He has authored numerous books, primarily on labour market segmentation, sex inequality, and comparative social stratification.Paweł B. Sztabiński is Professor of Sociology at the Institute of Philosophy and Sociology at the Polish Academy of Sciences. His main research interests include survey methodology, in particular non-response issues and mixed mode data collection.