Concepts and Methods in Commodity Flow Analysis

Commodity flow studies have been justly criticized for their conceptual poverty [36, p. 1]. Indeed, until the midfifties when some of Ohlin's [60] propositions about interregional trade were reformulated by Ullman [93, 94] into a verbal model of the bases for spatial interaction, the few geographers interested in commodity flows seemed to be preoccupied with the graphical presentation of statistics of traffic flow [16, 99]. Studies that simply annotate flow maps and diagrams (themselves generalized and therefore less accurate versions of the basic numerical data) have not ceased [83, 86, 91], but during the last decade there has been an increasing awareness of the need for concept and method in commodity flow studies [13, 35]. It is with these concepts and methods that this paper will be concerned.