Making a decision today is quite important, especially in companies, where the consequences can bring benefits or costs. Sometimes the decisions to be made are complex and we need to evaluate many criterions that can involve several factors. In those cases, it is not easy to have a good overview of all choices and for this reason it is important to have a system that helps us in making complex decisions, when it is not possible to evaluate all the alternatives manually. This thesis describes different algorithms and tools that can aid in the process of making decisions. Based on the review of existing tools a new web based application is proposed. The new tool, Decision Maker, uses both the full Analytical Hierarchical Process approach and Chainwise Paired Comparisons method to evaluate different alternatives.

Author of these thesis researches the ability Paired comparison method to predict the results in the presidential elections during January 2018 ( the first and the second round). The pair comparison method is based on the assessment of individual candidates in combinations (pairs) where two candidates stand against each other and there is a judge who compares them in all combinations. The author carried out an investigation using three standardized questionnaires. She has applied the method in the first questionnaire and surveyed the actual choice of the respondents in the other two questionnaires. There were 392 respondents who participated in the complete questionnaire surfy and their answers were analyzed and compared with their results of Paired comparison method. The thesis also shows the accuracy of the method and the suitability of the application, as well as the ability to predict the results of undecided voters. The Paired comparison method in prediction of the results of the first round, but was able to estimate the results of the second round. The author concludes that Paired comparison method should be used in several round types of elections or those where two candidates stand against each other. There are also examined the disadvantages and risks of the method.