New method for assigning cardinal weights in multi-criteria decision-making: the constant weight ratio method

A new method is proposed to convert ordinal ranking of a number of criteria and an additional piece of information into numerical weights. A literature review of methods for assigning cardinal weights based on ordinal ranking is performed, as well as an analysis of their behaviour. The new method, called ‘constant weight ratio’ (CWR), enables better adjustment to the decision-maker’s preferences than purely ordinal ranking methods. It also solves the problem of the excessive decrease in the weight of the most important criterion (or criteria) when the total number of criteria is large and the weight of the most important criterion (or criteria) must be high. It is achieved via three simple steps and flexible input data. The additional piece of information may be: (i) the relative importance of the criteria, i.e., the weight ratio, (ii) the total weight of the most important set of criteria, or (iii) the weight of the most important criterion. The proposed method is applied to two case studies in the cultural sector to illustrate that the resulting weights are equivalent to other methods requiring more input data from the decision maker.