Multicriteria Decision Aid (MCDA) is a framework for collecting, storing, and processing all relevant information, thus making the decision process traceable and transparent.
How is MCDA used in environmental planning and management? We know that there always be conflicts of importance between social, politic, environment, and economic aspects in the planning. Furthermore, there is also conflict of interest between stakeholders. MCDA can solve those conflicts by clarifying the planning process, avoiding various distortions, and managing all the information, criteria, uncertainties, and importance of criteria in objective way.
How it works?
First, we define the problem, considered criteria, and then we get a set of alternatives. Usually we will make partial ranking and acceptability analysis of the alternatives. The criteria consist typically of measures for technical feasibility, cost effectiveness, probable impacts, environmental impacts, etc. By the way, we have to make sure that the stakeholders are involved and participated in the process.
Stakeholders can be classified into standard stakeholders (have legitimate responsibility. Ex: decision makers, experts, planners) and interest groups (Ex: political parties, residents of impact area, civic organizations). The interest groups can be classified again as (1) boosters are those who see the issue as essential to their survival, (2) friends are those who see the issue as important thing but not essential to their survival, (3) guardians are those in neutral, (4) nonparticipants are those that are uninterested, (5) hostiles are those who often act against their own interest, and (6) preservationists are those who oppose the alternatives.
Defining Alternatives and Criteria
A finite set of alternatives are defined by stakeholders and are evaluated based on multiple criteria. Alternatives can be classified as standard and innovative ones. Standard ones are zero alternative and other alternatives presented by stakeholders. Innovative alternatives are those emerging through negotiations during the process. The criteria provide numerical measures for all relevant impacts of different alternatives. The impacts can be classified as temporal (unique, recurrent, and continuous), spatial (local, regional, national, international, and global), and regulatory (formally regulated or not regulated) properties.
The relevance of impacts depends of stakeholders’ point of view. So, it is important to involve all stakeholders. The final set of criteria should meet the requirements: (1) completeness, (2) operationality, (3) nonredundancy, and (4) minimality.
Usually the criteria are measured as aggregates of primary factors, which may consist of, for example, emission levels for individual chemicals, size of affected population, noise distribution in certain areas, etc. Sometimes the criteria measurements are based on expert judgements.
Choosing the Decision Aid Method
There are some requirements for the MCDA method to be used in public environmental problems:
- The method should be well defined and easy to understand, particularly regarding its central elements, such as modeling of criteria and definition of weights.
- The technique must be able to support the necessary number of DMs.
- The method must be able to manage the necessary number of alternatives and criteria.
- The method should be able to handle the inaccurate or uncertain criteria information.
- Due to time and money constraints, the need of preference information from the DMs should be as small as possible.
Some methods of MCDA
- Multiattribute Utility Theory
- Analytic Hierarchy Process
- Stochastic Multicriteria Acceptability Analysis (SMAA)
- Cost-benefit analysis
SMAA methods provide the most detailed information describing what kind of preferences correspond to the choice of each alternative. SMAA provides this information in the form of so-called acceptability indices that measure the variety of different preferences supporting each alternative, and central weights describing the preferences of a typical DM supporting a certain alternative.
Providing Preference Information
Commonly, in multicriteria problems a number is assigned for each criterion describing its importance. The interpretation of the weights depends on the shape of the utility function. Weight information can be more or less accurate. When exact weights cannot be obtained or agreed on, weight intervals or weight distributions can be used. Several techniques for eliciting weights are presented in literature. These vary from direct assessment to pairwise comparison methods such as AHP.
It is important to identify stakeholders’ points of view in environmental decision problems. One of the benefits of MCDA methods is thus that all stakeholders learn to understand the problem better. The MCDA approach has also increased discussion between different stakeholders, activated nonparticipants, and focused the discussion to relevant topics. It is important that the points of view significant for different interest groups be conveyed to the DMs.
Journal of Using Multicriteria Methods in Environmental Planning and Management by Risto Lahdelma, Pekka Salminen, and Joonas Hokkanes in year 2000.