Influence of aggregation and preference scale on ranking a compromise alternative in AHP

Analytic Hierarchy Process (AHP) is one of the most popular multi-attribute methods. However results depend on the preference measurement scale and the aggregation technique used. In this paper we describe a decision problem with an inherent trade-off between two criteria. A decision maker has to choose among three alternatives: two extremes and one superior "compromise". Seven different preference scales are considered for applying the additive and the multiplicative AHP. The results are compared with standard consumer choice theory. The multiplicative AHP, independently of the preference scales and the normalisation of the criteria weights, gives a real possibility to a compromise alternative to be selected and is therefore in agreement with the consumer choice theory. The role of the preference scale is more consequent with the additive AHP which is very unfavourable with the compromise alternative.