Bilateral international migration flow estimates for 200 countries

Abstract

Data on stocks and flows of international migration are necessary to understand migrant patterns and trends and to monitor and evaluate migration-relevant international development agendas. Many countries do not publish data on bilateral migration flows. At least six methods have been proposed recently to estimate bilateral migration flows between all origin-destination country pairs based on migrant stock data published by the World Bank and United Nations. We apply each of these methods to the latest available stock data to provide six estimates of five-year bilateral migration flows between 1990 and 2015. To assess the resulting estimates, we correlate estimates of six migration measures from each method with equivalent reported data where possible. Such systematic efforts at validation have largely been neglected thus far. We show that the correlation between the reported data and the estimates varies widely among different migration measures, over space, and over time. We find that the two methods using a closed demographic accounting approach perform consistently better than the four other estimation approaches.

Fig. 1

Overview of study design for estimation and validation of bilateral migration flows between all countries. Data for input and comparison shown in black and white. Data processing steps shown in boxes with shaded outlines. Resulting data shown boxes with shaded background.

Fig. 2

Total migration flows (in millions) and their corresponding crude migration rates (migrants per thousand people in the population) for five-year periods between 1990 and 2015 based on six flow estimation methods.

Fig. 3

Chord diagrams of estimated migration flows during 2010–2015 based on six methods. Direction of the flow is indicated by the arrowhead. The size of the flow is indicated by the width of the arrow at its base. Numbers on the outer section axis, which give the size of migration flows, are in millions of individuals per five-year period. Sector axis limits are based on maximums over all estimation methods and all five-year periods.

Fig. 4

Correlations between estimated migration flows during five-year periods from 1990 to 2015 from six estimation methods with equivalent reported migration flows.

Fig. 5

Correlations in five-year periods between estimated migration flows from six alternative estimation methods with equivalent reported migration flows.

Fig. 6

Correlations between estimated migration flows from six estimation methods with equivalent reported migration flows by development level of country.