Internal Migration Models and Population Forecasts

Almost any type of planning requires a population forecast. Migration is one of three components of population change—fertility, mortality, and migration. Several attempts have been made to establish meaningful relationship between socioeconomic and migration data. These attempts include Zipf’s interactance model; Stouffer’s intervening opportunities model; Somermeijer’s, Lowry’s, and Schwind’s gravity models with attraction indices; Blanco-Lowry population change due to migration models; Ichimura’s and Muth’s econometric models; Forrester’s Urban Dynamics model; and mobility behavioral models. Comparison and critique of these models have shown that econometric models and Blanco-Lowry models of population change due to migration are the most useful to planners. Econometric models require a level of cost and expertise not commonly found in most planning agencies. At their present state of development, mobility models are of little or no help to planners in terms of population forecasts. Migration models show promise of eventually becoming truly useful in connection with regional population forecasts.