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Systems that assist their users in the solution of ill-structured spatial problems. Spatial decision support systems are a special form of decision support system (Bonczek, Holsapple and Whinston, 1981). A spatial problem can be defined as one whose solution is embedded in a space, usually geographic space; examples include selection of sites for particular uses, or determination of the best routes between given origins and destinations. Such problems are ill-structured if it is impossible to know in advance the full set of criteria or constraints that will ultimately affect the solution (Hopkins, 1984). Frequently, additional criteria only become apparent once a tentative solution has been identified, or through involvement of additional stakeholders in the decision-making process. In such cases decision-making may extend over a substantial period of time, and the criteria and constraints may change repeatedly before the final solution is determined.
A spatial decision support system (SDSS) must be iterative, producing tentative solutions that can then be used as one basis for the revision of criteria and constraints, in a feedback process that may occur many times during the solution of a problem. With each iteration the problem becomes better-defined, and more inclusive of the views of all of the stakeholders. An SDSS is thus also participative, because the decision-makers and stakeholders play active roles in defining the problem, carrying out analyses and evaluating the outcomes; it would not be appropriate for these functions to be given to a specialized analyst. Finally, an SDSS must be integrative because value judgements that materially affect the final outcome are made by decision-makers who have expert knowledge that must be integrated with the quantitative data in the models.
There are strong similarities between SDSS and geographical information systems (GIS), and GIS often form the base on which SDSS are constructed. Although many practical SDSS have been built for special purposes (Gould and Densham, 1991), it has proven difficult to develop general-purpose software, or to minimize the effort involved in constructing an SDSS for a specific purpose. Thus the concept remains largely elusive, and is best treated as a model of decision-making practice rather than an accurate characterization. (MG)
References Bonczek, R.H., Holsapple, C.W. and Whinston, A.B. 1981: Foundations of decision support systems. New York: Academic Press. Gould, M.J. and Densham, P.J. 1991: Spatial decision support systems: a bibliography. Technical Paper 91-6. Santa Barbara, CA: National Center for Geographic Information and Analysis; Hopkins, L. 1984: Evaluation of methods for exploring ill-defined problems. Environment and Planning B: Planning and Design 11: 339-48. |
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