Due to the phenomenon of the technological paradox, much research has concentrated on measuring of the impact of the information systems and the information technology (IS/IT) on performance of the companies. The methods and the focus of research gradually evolved as the economy shifted from the industrial to the post-industrial, with rapid expansion of IT. The methods are quantitative, qualitative, or combination of both. The main contribution of this paper is the specification of the methods which could be used to determine the relative importance of the selected attributes. The authors propose one of the following methods: i) multiple regression with data analysis, ii) inductive logic programming, and iii) factor analysis or principle component analysis.