Impacts of using relative weights in multiple criteria decision making: a comparative study between independent- and overlapping-criteria decision problems

Multiple criteria decision analysis (MCDA) methods have been widely employed in real-life decisions. An assumption generally seen is that each criterion plays a role in determining the result according to its relative weight. However, signs of imprecision in relative weights have been implied in the literature, and this may indicate that they do not always provide intuitive and satisfactory conclusions. Most MCDA methods, furthermore, were performed regardless an existence of overlap among criteria although the decision theory reports the risk of obtaining a misleading conclusion from this. Due to the lack of empirical study to demonstrate such issues, this study investigates and supports the proposition that the relative weights do not precisely reflect actual contributions of decision criteria particularly when overlaps among criteria exist. Moreover, the use of the weights in such situation, through typical additive and multiplicative aggregation methods, is likely to generate a counter-intuitive or unsatisfactory conclusion.