I am Associate Professor at Erasmus University Rotterdam and the Director of ODISSEI (http://www.odissei-data.nl/), the Dutch National Infrastructure for Social Science, where I am responsible for the strategic development of the infrastructure and international collaborations. I’m deeply passionate about improving social science data and the infrastructure that is needed for its collection, processing and dissemination. I believe that the social sciences can help us understand and improve society, but to do so we must improve and diversify the data we use in social research. Because of this, I am a strong advocate of open science and the FAIR principles. I also conduct research on family sociology and demographic behaviour. Good demographic data is the vital basis for understanding all manner of social issues from changes in consumer trends through to assessing environmental impacts. You need to know how many people there are, and who they are.