Migration stocks and flows are needed to understand international migrant patterns and trends and to monitor and evaluate migration-relevant international development agendas. However, the lack and inconsistency of migration flow data across countries prevents effective comparisons. In this seminar, Professor Guy Abel will discuss two approaches that have been proposed to quantify bilateral migration flows between all country pairs of origin and destination. Professor Abel will give an overview of both approaches, as well as the techniques that have been developed to try to validate and compare the accuracy of the results.