Suessmilch Lecture | November 28, 2016

Evaluating multi-regional population projections

On December 1, 2016 Joel E. Cohen from the Rockefeller University, NY, USA, will give a talk at the MPIDR entitled "Evaluating multi-regional population projections with Taylor's law of mean-variance scaling and its generalization".


Organizations that develop demographic projections usually propose several variants with different demographic assumptions. Existing criteria for selecting a preferred projection are mostly based on retrospective comparisons with observations, and a prospective approach is needed. We used the mean-variance scaling (spatial variance function) of human population densities to select among alternative demographic projections. We tested against observed and projected Norwegian county population density using two spatial variance functions: Taylor's law (TL) and its quadratic generalization. We compared each function’s parameters between the historical data and six demographic projections, at long term (1978-2010 versus 2011-2040) and short term (2006-2010 versus 2011-2015) time scales. We found that short-term projections selected by TL agreed more accurately than the other projections with the recent county density data and reflected the current high rate of international migration to and from Norway. The variance function method provides an ex ante approach to evaluating short-term human population projections. This presentation is based on joint work with Meng Xu, Pace University, New York City, and Helge Brunborg, retired from Statistics Norway, Oslo. This work is in press in Journal of Population Research. We acknowledge US National Science Foundation grants EF-1038337 and DMS-1225529 to the Rockefeller University.

About the speaker

Joel E. Cohen is the Abby Rockefeller Mauzé Professor of Populations and head of the Laboratory of Populations at the Rockefeller University and Columbia University, New York. At Columbia University, he holds appointments in the Earth Institute and the Department of International and Public Affairs and Department of Earth and Environmental Sciences; and is affiliated with the Department of Statistics. He is a Visiting Scholar in the Department of Statistics of the University of Chicago.

Joel E. Cohen studies the demography, ecology, epidemiology and social organization of human and non-human populations and mathematical concepts useful in these fields. He earned doctorates in applied mathematics in 1970 and population sciences and tropical public health in 1973 from Harvard University. He has published 14 books (4 written as sole author, 4 co-authored, 5 edited, and one translated) and more than 410 papers and chapters.

Time and Venue

Thursday, December, 2016, 3 p.m, in the Institute's Auditorium