In defense of the net migrant

Abstract

Net migration has been widely criticized as a theoretical concept and as a measure of population movement. Many of these criticisms are valid: net migration reflects a residual rather than a true migration process, it often masks large gross migration flows, it cannot account for differences in the characteristics of origin and destination populations, it cannot be used for rates in a probabilistic sense, and it can lead to misspecified causal models and unrealistic population projections. However, we believe there are purposes for which net migration is very useful, especially for analyses of small areas: 1) It provides a summary measure of one component of population change; 2) It can be used when gross migration data are unavailable or unreliable; and 3) It provides a low-cost alternative to the use of gross migration data. In this paper we discuss the strengths and weaknesses of net migration and provide several examples of how it can be useful for population estimation, forecasting, and analysis.