Their distinctive feature is the rejection of comparing the merits and drawbacks of all alternatives on the basis of the values of calculated overall criterion estimates, and the application of simple heuristic rules. The purpose of this rejection is to exclude from consideration a large number of unpromising, inefficient alternatives so as to examine only a small number of them and make a reasonable choice. This group of choice strategies includes the dominance strategy, the conjunctive strategy, the disjunctive strategy, the lexicographic strategy and the elimination-by-aspects strategy:
- • the dominance strategy is aimed at finding an alternative that is no worse than the others on all parameters, and is better than all the other choice options on at least one parameter. This strategy makes it possible to exclude certain alternatives from consideration and to reduce the set of alternatives remaining for consideration. For example, when choosing to buy a dacha, the value of a parameter such as «price» is taken into account, but only on condition that the values of the parameters «age of the building» and «availability of public transport» for the alternatives that remain under consideration are acceptable to the DM. A feature of applying this strategy is that it makes it possible to find the best alternative, but only if one exists. Compensatory strategies possess the same capabilities, but the advantage of the dominance strategy is its simplicity;
- • the conjunctive strategy excludes alternatives that do not satisfy the minimum requirements on all parameters simultaneously, and selects the first satisfactory alternative, if one exists. For example, when making a decision on purchasing a dacha, in accordance with the conjunctive strategy, the dacha option with an acceptable age of the building is chosen, but only among alternatives that have an acceptable price and public transport. Alternatives without public transport and with a high price are discarded in advance. If a satisfactory solution is not found, the list of alternatives must be expanded by relaxing the requirements for individual parameters of the alternatives. The conjunctive strategy is consistent with the concept of bounded rationality, according to which a reduction in the number of alternatives under consideration is achieved by selecting, from among all alternatives, those that satisfy the DM's requirements to a certain degree;
- • the disjunctive strategy evaluates each alternative by its best qualities, regardless of the values of the alternative's other parameters. Only those alternatives that have the best values for any one of their parameters remain for the final decision. For example, when buying a car, the best alternative by price (the cheapest) is found first, then alternatives by prestige may be examined — the most prestigious of all is found; then — by power, and so on. The choice of the final parameter by which the final option is adopted is left to the DM;
- • the lexicographic strategy is similar to the disjunctive strategy, but differs from it in that alternatives that are the best among all on the most important parameter are selected first. If there are several such alternatives, then among them the best on the most important of the remaining parameters are again identified, and so on, until the number of options is reduced to an acceptable one. For example, when buying a car, the best alternative by power is found, then, if several such alternatives remain, — by prestige, and so on;
- • the elimination-by-aspects strategy is comparable to the lexicographic strategy, but is based on the principle of rejecting alternatives. First, alternatives that do not satisfy the requirements on the most important parameter are removed, then, among those remaining, alternatives unsuitable on the less important parameter are excluded, and so on, until one or several options remain for the final choice. By analogy with the previous example, the least prestigious car models are removed first, and among those remaining — the least suitable by power, and so on.
Please note!
- 1. Decision-making on many criteria simultaneously requires the use of special decision-making strategies.
- 2. When choosing the final decision option, as a rule, not a single strategy is used, but a combination of them.
3. Reducing the set of alternatives to reasonable limits is, as a rule, carried out on the basis of elimination strategies. If several options remain after this, the best of them is determined on the basis of one of the compensatory strategies.
Note that the subjective factor of human behavior manifests itself especially clearly in the choice of the method for aggregating many criteria into one and in the selection of the method for calculating the final overall criterion estimate, which is reflected in the implementation of various compensatory strategies of multi-criteria choice.
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