Weighting-scaling, weighting-ranking, or weighting-rating checklists are valuable for displaying tradeoffs between alternatives and their associated environmental impacts; thus they are useful in selecting a proposed action. Computerization of these decision-focused checklists is a current trend. The following observations pertain to this category of EIA methods:
1. Several approaches are available for assigning importance weights and for achieving scaling, rating, or ranking. These approaches have relative features and can be considered in choosing the approaches to be used in a study.
2. The process used for importance weighting of the individual decision factors and the rationale used in determining the relative importance weights of individual factors must be described. The rationale used for the scaling, rating, or ranking of individual alternatives relative to each decision factor must also be described. In fact, the description of the rationale is probably more important than the final numerical scores or classifications which result from them.
3. The most debatable point relative to weighting-scaling, -rating, or -ranking checklists is the assignment of importance weights to individual decision factors. Several approaches for importance weighting involve the use of public participation. Where this participation can be incorporated, it should legitimize the overall decision-making process.
4. The use of these checklists can structure the decision process in comparing alternatives and selecting the one to become the proposed action. The process of using these checklists can structure the decision process and provide a tradeoff basis for comparisons and evaluations of alternatives.
5. Due to the similarities between these decision-making approaches for environmental studies and other types of decision-making approaches, a wide range of computer software has become available within recent years to aid the process. This computer software is typically user friendly and can guide the assignment of importance weights and the scaling, rating, or ranking of alternatives. The software can then be used to calculate final index scores for each alternative. In addition, due to the availability of computer software, sensitivity analyses of the overall decision process can be easily conducted by examining the influence of changes in importance weights as well as impact scaling, rating, or ranking assignments to individual alternatives. Use of software for sensitivity analysis can indicate the relative sensitivity of the scores to individual changes.
6. The weighting-scaling, -rating, or -ranking checklist must be kept simple to facilitate the decision-making process. Additional alternatives and decision factors do not necessarily indicate that a better overall decision will be made.
7. These types of checklists can be used at several points in overall project planning and decision making. For example, they can be used early in a study to reduce the number of alternatives to allow a more detailed analysis of a smaller number of alternatives. In addi tion, using this process can reduce the number of decision factors so that in the final selection, a smaller number of alternatives is compared in relation to the key decision factors.
8. Use of these checklists forces decision making in context; that is, it keeps the decision maker from giving too much attention to a single issue in the decision-making process. It forces the decision maker to consider each issue and impact in relation to other issues and impacts.
9. These checklists can be used for several types of decision making, based on other considerations than environmental. They can also be used for decision making that evaluates and compares the environmental impacts as well as economic characteristics of different alternatives. Finally, such approaches can be used for systematic decision making considering environmental impacts, economic evaluations, and engineering feasibility. In other words, their use can range from considering only the environment to considering a composite of the three "Es" of decision making (environment, economics, and engineering).
Was this article helpful?