A Gross Migration Optimization Technique of Developing In- and Out-Migration Assumptions for Regional Population Projections

S. Simon Choi, Southern California Association of Governments

Gross migration approach may produce more adequate population projections than net migration approach for several reasons. But, gross migration approach is not popular among local demographers due to the limited availability of gross migration data and the difficulty in its application. This study proposes a gross migration optimization technique of developing reasonable in-migration and out-migration assumptions for local population projections. The gross migration optimization technique is designed to produce gross in-migration and out-migration assumptions by efficiently finding optimal adjustment factors for the plus-minus adjustment method. The major advantage of this gross migration optimization technique is to immediately develop the size of in-migration and out-migration, while maintaining acceptable age and sex specific in-migration and out-migration schedules. The gross migration optimization technique is applied to regional population projections of Southern California in an economic-demographic modeling framework. The gross migration optimization technique is useful and easily applicable in developing reasonable in-migration and out-migration assumptions.