Spatial Interaction Models

Abstract

This article examines some of the basic elements of spatial interaction models. Spatial interaction is the general term for any movement of people, goods, or information over space that results from a decision-making process. Specific examples include movements such as migration, shopping trips, commuting, trips for recreational purposes, trips for educational purposes, freight flows, the spatial pattern of telephone calls, emails and world-wide web connections, and even the use of healthcare facilities. Spatial interaction models are mathematical descriptions of spatial flows. The models serve two purposes. One is to predict flows where they are unknown such as the impact on traffic patterns of a new development or the impact of a new retail outlet or healthcare facility. The other is to yield information on the determinants of the flow system being analyzed. For example, spatial interaction models are commonly used by retailers to determine the influence of various store attributes on the choice of stores by consumers or by government agencies to examine the characteristics of places which affect in and out migration. This article describes four common types of spatial interaction models and outlines a typical application of each type of model. Brief discussions of model calibration and local forms of spatial interaction models are then given followed by a description of the various underlying theoretical structures that have been proposed to substantiate spatial interaction models.