by Tamás Rapcsák
In everyday life we continually make decisions, even if we do not think of that. The scope of these decisions ranges from the slightest problems, like `Shall I take my umbrella with me?', to economic questions of great importance. The need for helping the proper decision making has brought up several decision support methods along the history - from the ancient prophets to the sophisticated decision support systems of our times, e.g., EXPERT CHOICE (Saaty), ELECTRE III and IV (Roy), PROMCALC (Brans and Mareschal).
A flexible framework for group decision support on PCs in Microsoft Windows environment was developed in the Department of Operations Research and Decision Systems. WINGDSS does not replace human judgement but highly supports the entire process of decision making from problem structuring to post-decision analysis. The latest version of WINGDSS is a modular, open system with a dynamic connection to relational databases, an interpreter for defining problem specific evaluation procedures, a lot of interactive features from setting up the tree of criteria to the sensitivity analysis on individual/group ranking. By providing tools for recursively redefining the decision problems, WINGDSS helps the decision makers in achieving a result satisfactory to the whole group. By experience with real life decision problems, the requirements arose for improving the techniques to visualize the steps of decision processes and present the results. Visualization seeks to provide suitable representations for complex problems.
Modern decision support systems intend to offer a user-friendly software environment to describe the decision problem, to solve it and to present the results in an attractive and clear visual form. In our system, a software environment supporting the visualization in the decision support system WINGDSS 4.0 was developed. Although decision models can grow and spread quite large, no graphical representation scheme is commonly used in decision systems. In WINGDSS 4.0, a multi-window, mouse-driven user interface is developed which can be easily learnt and applied. In the conceptual model, the criteria have a natural graphical representation by using a software module to build the trees of criteria based on the relations and hierarchy between them.
Spreadsheets have proven to be a very useful aid in solving problems. In order to use spreadsheets as a visualization tool, Excel was linked with WINGDSS 4.0. So, they were applied by formulating decision problems in the case of one decision maker, by collecting data and refining the system of weighing. To plot the solution of sensitivity analysis, i.e., the final ranking values of the alternatives as functions depending on some parameters, and to present graphics summarizing the results as pie-charts and bar-charts, the tools of Excel are used (see figure 1).
In this version, outer programs can be linked with this decision support system framework. In decision problems containing a large-scale linear optimization model, a matrix editor may help to check the input data, recognise special structures by color-coding negative and positive elements with different colors and facilitate the modifications of the model. The solution of some decision problems (e.g., in environmental issues) can be based on digital database and graphically represented on a map. This is the motivation of having developed a GIS module in WINGDSS 4.0 (see figure 2). The textual and graphical representations of the results can be printed on commonly used paper-sheets, in course of which the most difficult problem was how to decompose and produce large-scale criteria-trees depending on concrete problems.
Some applications are as follows: