Jos W. R. Twisk is a professor in applied biostatistics at the department of Epidemiology and Data Science of the Amsterdam University Medical Centers (AUMC). He studied human movement science in Amsterdam, and after his graduation in 1990, he joined the research team of the Amsterdam Growth and Health Longitudinal Study. After his PhD, which was related to this longitudinal study, he supervised several projects within the AGHSL. In 2005, he was appointed as a full professor of applied biostatistics. His main activities nowadays involve teaching (at several levels) and providing consultancies to researchers from the AUMC and other universities from inside and outside the Netherlands. He has written several textbooks on longitudinal data analysis, mixed model analysis and the analysis of randomized controlled trial data. He also conducts applied methodological research and is the (co)author of more than 1000 peer reviewed scientific papers.