Patrick Gerland is the chief of the Population Estimates and Projections section of the Population Division within the United Nation’s Department of Social and Economic Affairs. He oversees the preparation of technical and substantive reports on population estimation and projection published by the UN. During his professional career, Patrick provided technical training and assistance to population data-related projects in over 30 countries in Africa and Asia; collaborated in numerous inter-agency substantive and methodological expert groups; and has been collaborating with several academic research groups to develop new state-of-the-art statistical methods to incorporate uncertainty in demographic modeling, population reconstruction and probabilistic projections relevant to the UN work, and to improve existing methods and empirical datasets to measure child, adult and old-age mortality. Patrick has also published extensively. He holds a DESS d’expert démographe from the University of Paris (IDUP, Paris-I Pantheon-Sorbonne) and a PhD in Population Studies from Princeton University (Office of Population Research).