The comparative analysis of MCDA methods SAW and COPRAS

In recent years, quantitative multicriteria methods have been widely used for comparative evaluation of complicated technological and social-economic processes, as well as for determining the best alternative among the available options and ranking the alternatives based on their significance for a particular purpose. Professor of Vilnius Gediminas Technical University E.K. Zavadskas was the first to use these methods in Lithuania in the mideighties of the last century for evaluation, substantiation and choosing of optimal technological solutions at various stages of construction (Завадскас 1987). In this period, new multicriteria evaluation methods were being developed and widely used in the world in various scientific and practical areas. Later, numerous disciples and colleagues of prof. Zavadskas as well representatives of various scientific schools extensively used the considered methods in Lithuania. The main concept behind the quantitative evaluation methods is integration of the values of the criteria describing a particular process and their weights (significances) into a single magnitude, i.e. the criterion of the method. For some particular (maximizing) criteria the largest value is the best, while for others (minimizing criteria) the smallest value is the best. The units of criteria measurement are also different. The alternatives compared are ranked according to the calculated values of the criterion of the method. Great numbers of multicriteria evaluation methods, based on different logical principles and having different complexity levels and the inherent features, have been created in the world. There is hardly any ‘best’ multicriteria evaluation method. Therefore, a parallel use of several multicriteria evaluation methods as well as the analysis of the spread of estimates and averaging of the values obtained may be recommended for evaluating complicated multifaceted objects and processes.The method SAW (Simple Additive Weighting) is one of the simplest, natural and most widely used multicriteria evaluation methods. It clearly demonstrates the idea of integrating the values and weights of criteria into a single estimating value – the criterion of the method. However, SAW uses only maximizing evaluation criteria, while minimizing evaluation criteria should be converted into the maximizing ones by the respective formulas prior to their application. This limitation is eliminated in the method COPRAS (Complex Proportional Assessment). The authors of the method, E.K. Zavadskas and his disciple A. Kaklauskas suggested that the influence of maximizing and minimizing evaluation criteria should be assessed separately. In this case, the component, taking into account the effect of maximizing criteria, matches the estimate yielded by the method SAW. Despite the fact that the method COPRAS is most commonly used in Lithuania, its main characteristics and properties have not been clearly defined and demonstrated. However, the awareness of these properties allows us to show the benefits of the method’s application, to predict the influence of minimizing criteria values on the final result (estimate), to check the calculations and to take into account possible instability of estimates yielded by the method due to the specific character of the actual data. The paper describes the main features of multicriteria evaluation methods SAW and COPRAS and their common and diverse characteristics, as well as defining and demonstrating the properties of the method COPRAS, which are of great theoretical and practical value. All theoretical statements are illustrated by numerous examples and calculations.The method SAW (Simple Additive Weighting) is one of the simplest, natural and most widely used multicriteria evaluation methods. It clearly demonstrates the idea of integrating the values and weights of criteria into a single estimating value – the criterion of the method. However, SAW uses only maximizing evaluation criteria, while minimizing evaluation criteria should be converted into the maximizing ones by the respective formulas prior to their application. This limitation is eliminated in the method COPRAS (Complex Proportional Assessment). The authors of the method, E.K. Zavadskas and his disciple A. Kaklauskas suggested that the influence of maximizing and minimizing evaluation criteria should be assessed separately. In this case, the component, taking into account the effect of maximizing criteria, matches the estimate yielded by the method SAW. Despite the fact that the method COPRAS is most commonly used in Lithuania, its main characteristics and properties have not been clearly defined and demonstrated. However, the awareness of these properties allows us to show the benefits of the method’s application, to predict the influence of minimizing criteria values on the final result (estimate), to check the calculations and to take into account possible instability of estimates yielded by the method due to the specific character of the actual data. The paper describes the main features of multicriteria evaluation methods SAW and COPRAS and their common and diverse characteristics, as well as defining and demonstrating the properties of the method COPRAS, which are of great theoretical and practical value. All theoretical statements are illustrated by numerous examples and calculations