A linkage between GIS and spatial data analysis is considered to be an important aspect in the development of GIS into a
research tool to explore and analyze spatial relationships. The limited availability of advanced analytical capabilities in commercial
GIS packages is by now a familiar complaint in the research literature, going back to Goodchild (1987), and several calls for a closer
integration between spatial analysis and GIS have been formulated (e.g., Openshaw, 1990). In the past few years, this has resulted in
considerable research activity in this area, as evidenced by an increasing number of review articles, conceptual outlines, and guides for
practical implementation of the Linkage, e.g., in Anselin and Getis (1992), Bailey (1992), Fischer and Nijkamp (1992), Goodchild et
al. (1992), and Anselin, Dodson and Hudak (1992).