Tommy Bengtsson is Professor of Demography and Economic History, Lund University. He received his doctoral degree from Lund University in 1980 on a dissertation on 20th century technological change and labor market issues. Afterwards, he started to work in the area of population economics, especially on demographic response to short-term changes in real wages using historical records at macro level for Sweden. Next, he combined an event history approach with a time-series approach to analyze the effects of changes in real wages on demographic outcomes at micro level. Later, he used a similar approach studying the effects of conditions in early life on health and socioeconomic performance later in life. To be able to do so, he build up the Scanian Economic Demographic Database (SEDD), which is closing the gap between the historical and contemporary datasets and today, the Centre for Economic Demography (CED), which he started in 2006, is administrating the database. Bengtssonhas also been involved in studies on population ageing and welfare state as well as on the current immigration to Sweden.   Nico Keilman is Professor of Demography at the Department of Economics, University of Oslo, since 1994. He studied applied mathematics and demography at the universities of Delft and Utrecht, and received his doctoral degree at the latter university in 1990, for a dissertation on the accuracy of population forecasts. He has more than 30 years of experience in mathematical and statistical research on demographic models for the dynamics of living arrangements, mortality projections, and demographic methods in general. From 2006 until 2011, he was the editor of Demographic Research.