Efficiency is a core concept of multi-objective optimisation problems and multi-attribute decision-making. In the case of pairwise comparison matrices, a weight vector is called efficient if the approximations of the elements of the pairwise comparison matrix made by the ratios of the weights cannot be improved in any position without making it worse in some other position. A pairwise comparison matrix is called double perturbed if it can be made consistent by altering two elements and their

more »

... iprocals. The most frequently used weighting method, the eigenvector method is analysed in the paper, and it is shown that it produces an efficient weight vector for double perturbed pairwise comparison matrices.