Assessing Uncertainty in Fertility Estimates and Projections

Leontine Alkema, University of Washington
Adrian Raftery, University of Washington
Patrick Gerland, United Nations
Samuel J. Clark, University of Washington
François Pelletier, United Nations

The United Nations Population Division produces estimates and projections of the total fertility rate for all countries in the world every two years. For countries with fertility above replacement level, future levels are projected based on a parametric function. We develop a Bayesian hierarchical model for producing probabilistic projections of fertility. Differences in data quality for observations within a country are assessed by relating a standardized weighting scheme to the empirical variance of the measurement errors. We quantify the country-specific uncertainty in future fertility, as well as in the estimates of past levels of fertility, and we give results for a number of Asian and African countries.