A revised notation is developed in which the accounting and model relationships that characterize multiregional population systems can be expressed. The variable K represents population as a stock, as a flow, and as an event count. People move from one state and location to another state and location over time. A special set of location—state labels for variable K describe the transitions possible. The hope is expressed that the notation will contribute to fruitful synthesis in the field of spatial demography.
Guest Editorial: Spatial demography in regional science
