  Estimates of future migration patterns are a crucial input to world
population projections. Forced migration, including refugee and asylum seekers,
plays an important role in overall migration patterns, but is notoriously
difficult to forecast. We propose a modeling pipeline based on Bayesian
hierarchical time-series modeling for projecting combined refugee and asylum
seeker populations by country of origin using data from the United Nations High
Commissioner for Human Rights (UNHCR). Our approach is based on a conceptual
model of refugee crises following growth and decline phases, separated by a
peak. The growth and decline phases are modeled by logistic growth and decline
through an interrupted logistic process model. We evaluate our method through a
set of validation exercises that show it has good performance for forecasts at
1, 5, and 10 year horizons, and we present projections for 35 countries with
ongoing refugee crises.
