The doubly constrained model of spatial interaction: a more general formulation

Concerned with the doubly constrained case of spatial interaction models, this paper introduces a general functional form that subsumes the usual multiplicative (Wilson) and additive (Tobler) variants as extreme variants. Specifically, this formulation depends on a scalar <i>lambda</i> allowed to vary between 0 (multiplicative case) and 1 (additive case). A computational procedure is suggested and then illustrated by means of an application to interregional migration data.