Dr. Mark Trappmann is Professor of Sociology, especially Survey Methodology. His research focuses on error sources in surveys like coverage, nonresponse or measurement error and on procedures to correct or reduce these errors. As research director of the PASS panel survey (http://fdz.iab.de/de/FDZ_Individual_Data/PASS.aspx) his other interests are in research on poverty dynamics and working poor. Amongst other outlets, his research was published in academic journals such as Public Opinion Quarterly, Kölner Zeitschrift für Soziologie und Sozialpsychologie or Journal of Applied Social Science Studies.