NOTES ON SPATIAL INTERACTION

With this article, THE PROFESSIONAL GEOGRAPHER introduces a new type of Views and Opinions piece focusing upon key issues confronting particular segments of the discipline. The editors hope that such expressions of opinion will generate a productive exchange of views. In this paper, the author finds that log-linear regression estimates of the aggregate gravity model impose considerable technical problems. Entropy models do not provide a theory for the gravity model. Both approaches suggest that the performance of this model can be attributed to its tautological structure. Neglect of accessibility factors helps explain underestimation of travel demand in many studies. Individual choice theory does not realistically support the idea that the gravity model is superior to opportunity models. In addition, the whole notion of using observed behavior to “reveal” spatial decision-making must be seriously questioned.