Destination interdependence and the . competing - ' destinations model

There are two types of destination interdependence; one arises because of people's preferences towards destination activities, and the other because of the locational arrangement of space. Destination interdependence affects spatial behaviour. In a previous paper it was shown that the conventional gravity model can handle neither aspect of destination interdependence. In this paper it is shown that the competing-destinations model, as a reformulated gravity prototype, is at best able to describe only locational structure effects. 1 The problem The gravity model has been criticized for being 'misspecified' [see Sheppard (1984) for a review] in the sense that the model does not capture contextual effecs, and the competing-destinations model was proposed to overcome this problem (Fotheringham, 1983a). The literature contains reports on two types of context: the socioeconomic context that constrains the decisionmaker's choice (Burnett and Hanson, 1982; Hagerstrand, 1970; Pred, 1977), and the structural context of locational configurationw and consumer preferences (Borgers and Timmermans, 1987; Eagle, 1988; Fotheringham, 1981; Lo, 1991a). It is the structural context of spatial interaction or destination interdependence that has preoccupied recent attention. Previous attempts to examine destination interdependence have concentrated mostly on the locational structure issue, with insufficient attention given to the economic preference question (Cliff et al, 1974; Curry, 1972; Fotheringham, 1983a; Griffith and Jones, 1980; Ishikawa, 1987; Roy, 1985). Although Fotheringham (1983b) and Roy (1985) recognized economic substitution, the idea was not systematically treated until I wrote about the distinction between locational and economic interdependence (Lo, 1991a). I feel that the competing-destinations model is capable of distinguishing locational structure effects but not economic preference effects. A simulation approach is used to test systematically a system-wide competing-destinations model across experimentally controlled choice contexts incurring different types of locational, as well as economic, interdependence. Although much of the spatial interaction literature on the gravity model has included both migration and retailing as examples, the literature on the competing-destinations model has so far relied heavily on the migration context. In this paper I use a retailing context to examine the competingdestinations model. The objective is to see if all aspects of destination interdependence are considered in this model. There is no a priori assumption that locational interdependence is relevant only to migration and that economic interdependence is relevant only to retailing. (1) As in Lo (1991a), I am hesitant to use the term 'spatial structure' although it is commonly used. I believe spatial structure is a term that encompasses various aspects of space, including its form, elements, organization rules, and interaction behaviour. <> In previous attempts, Fotheringham (1983a; 1984; 1986) and Ishikawa (1987) used real world data to test origin-specific competing-destinations models.