To achieve systematic decision making among alternatives, tradeoff analysis should be used. Tradeoff analysis involves the comparison of a set of alternatives relative to a series of decision factors. Petersen (1984) notes that in a tradeoff analysis, the contributions of alternative plans are compared to determine what is gained or foregone in choosing one alternative over another. Table 2.5.1 displays a tradeoff matrix for systematically comparing the groups of alternatives or specific alternatives within a group relative to a series of decision factors (Canter, Atkinson, and Leistritz 1985).
The following approaches can be used to complete the tradeoff matrix in Table 2.5.1:
1. Qualitative approach: Descriptive, synthesized, and integrated information on each alternative relative to each decision factor is presented in the matrix.
2. Quantitative approach: Quantitative, synthesized, and integrated information on each alternative relative to each decision factor is displayed in the matrix.
3. Ranking, rating, or scaling approach: The qualitative or quantitative information on each alternative is summarized via the assignment of a rank, rating, or scale value relative to each decision factor (the rank or rating or scale value is presented in the matrix).
4. Weighting approach: The importance weight of each decision factor relative to each other decision factor is considered, with the resultant discussion of the information on each alternative (qualitative; quantitative; or ranking, rating, or scaling) being presented in view of the relative importance of the decision factors.
5. Weighting-ranking, -rating, or -scaling approach: The importance weight for each decision factor is multiplied
TABLE 2.5.1 TRADEOFF ANALYSIS FOR DECISION MAKING (CANTER, ATKINSON, AND LEISTRITZ 1985)
Decision Factors 1 2 3 4 5
Degree of Meeting Needs and Objectives Economic Efficiency Social Concerns
(public preference) Environmental Impacts Biophysical Cultural Socioeconomic (includes health)
by the ranking, rating, or scaling of each alternative, then the resulting products for each alternative are summed to develop an overall composite index or score for each alternative; the index may take the form of:
Index j = the composited index for the jth alternative n = number of decision factors IWt = importance weight of ith decision factor Rj = ranking, rating, or scaling of jth alternative for ith decision factor
Decision making which involves the comparison of a set of alternatives relative to a series of decision factors is not unique to considering environmental impacts. This decision-making problem is classic and is often referred to as multiattribute or multicriteria decision making, or decision analysis.
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