The comparison analysis is published in details in [3].
1. The decision aim is the selection of optimised ordnance of an artillery battery of a mechanized infantry battalion.
2. Infantry battalions most generally are equipped with 120mm mortar battery, but there are also different cases for example with a smaller than 150mms howitzer. The combat procedures are continuously developing that implies the change of weapons this is why the 120mm and the 81mm mortar are being compared. During the selection of weapons the ordnance manufactured by ally and the possible hostile countries were taken into consideration, because the determination of a proportion or a preference can be important that show the relationship of weapons between our own and the enemy’s. The weapons in the paper are not mentioned in detail to avoid any promotions.
3. Starting from the aims of the decision maker and taking into consideration the ordnance the following criterion were determined: rate of fire, range, fragment effect, displacement time and battlefield mobility. During the research economical point of views were not taken into considerations, because these monetary sums are only available in details during the acquisition process. The authors do not wish to spoil the accuracy of the comparison with the use of estimated values only.
4. The weighing of point of views was made by the AHP method. For the weighing a form was applied that are used for the AHP a method and AHP questionnaire was
33 filled out by thirty competent people (expert). From the results, it can be stated that, the opinion of the importance of the criteria of the experts are significantly different, that requires further research. This result is explained in chapter 4 of this paper. 5. The comparison were made by the AHP analysis, the results are shown in Figure 1. 6. In Figure 1 the comparison of two 81mm and two 120mm mortar is shown. The
figure shows two values for the 120mm mortar referring to the classical high explosive shell and the extended range shell (rocket assisted). From the Figure 1 it is clear that taking into consideration only the high explosive shell, there is no significant difference between the 81mm and 120mm mortar but the firepower of the 120mm mortar is evidently much larger. The advantage of the larger calibre weapon is only evident in the case of the extended range shell. The approximate identity of the measurement of overall effectiveness of 120mm and 81mm mortals is a result of the criteria and its weights. Those points of view were taken into consideration where the smaller calibre weapons have an advantage. The example shows well that how the selection of the points of views meaning the determination of the precise aims of the decision maker effects the outcome of the valuation. These results are further examined in chapter 4 of this paper.
4 Solution for a Group Decision Problem 4.1 Group Decision Problem of artillery pieces
For the formulation of the problem firstly the decision making person have to be clarified. In the case of a military device the decision making person is the one who makes the selection considering the given method from the incoming proposals for the given ordnance. The advantages and disadvantages realised by the decision effects many people and also many people take part in the preparation of the decision. The documentation of the tender is prepared according to the aims of the decision maker that identifies what functions and utility has to be satisfied by the purchased ordnance. In addition the documentation has many projections: financial, user, technical, logistical. Several experts take part in the preparation, most often: economical, technical and user. The experts establish their preferences according to their own point of views. An economical expert has a different scale of value than a user. A significant opinion difference can also be between the users, due to the fast development of military technology and the continuous changing of combat procedures.
In many cases the decision making process can be considered as a future estimation, where the decision maker tries to estimate the usage in the future of the ordnance to be purchased and based on this estimation rank them.
HE HE HE HE ER ER 0 0,2 0,4 0,6 0,8 1 1,2 M1 M2 M3 M4 81 mm 120 mm
34
In the case when the decision maker is searching for the correct solution by depending upon the knowledge of more experts, can experience the dispersion of the opinion of the experts. The correct solution should be searched through the expert opinions. The difference of opinions can contain important information especially if it appears on the user’s side. The expert’s opinions of the preference of the considerations of experts were measured during the comparison of ordnance and are shown in Figure 2 by box- plot analysis.
From Figure 2 it is clear that by taking the importance of expert opinions, a considerable difference can be seen, not regarding the shooting distance. The opinion difference can be caused by hidden information that the decision maker has to know. A solution of the consensus search of group decision problems is offered by stochastic APH, where the experts’ pi/pj preference distribution is analysed, a solution is given in
[5].
The consensus among opinions has many disadvantages. The average, no matter how it is determined, would not represent the scale of value of all the participant and it would lead to the loss of information. The difference in opinion in general has a well defined reason. These are usually kind of non general opinions that are supported by one part of the experts and rejected by others. It can serve as important information for the decision maker. A good example of this is presented in the research of [3], of which a relevant part of it is shown in Figure 3. The research in [3] where the experts were ranked into groups by the help of multidimensional scaling and hierarchical cluster analysis according to their relevant opinion of the weight numbers of their criteria. Experts with nearly the same opinions are collected in these groups forming the so called opinion centre these opinion centres are identifiable with indicating reasons.
Figure 3 shows the averaged weight numbers opinion of two opinion centres. The most significant is the different judgement of the points of view of the firepower (rate of fire, range, and fragment effect) and the point of views considering the size and weight of
the device (displacement time, mobility). In Figure 3, group “A” prefers the large firepower less mobile while group “B” the smaller firepower but more mobile device. The following problem occurs during averaging, that before designating the experts the opinion centres are not known and there is no sampling procedure lacking the previous knowledge that with its accessible help every opinion centres is represented by the
order 1 2 3 4 5 Rate of fire Range Fragment effect Displace- ment time Battlefield mobility
35 sufficient number of experts. In the example group “A” had the larger number of participants, but this does not mean that this opinion is the determinant.
The experts in group “B” without any exception had foreign mission experiences. The results can also be explained by, that there are opinions that the smaller calibre, lighter and more battlefield movable devices are desirable, but these are only indicated by the expert’s own foreign mission experiences. In all cases this supplementary information from the group decision process has to be dealt with on its proper level by the decision maker.