Incorporating negative values into the Analytic Hierarchy Process

This paper describes why and how ratio scaled multiple criteria analysis techniques, such as the Analytic Hierarchy Process (AHP), should allow for a subtraction mechanism whereby negative preference (aversion) is combined with positive preference. The main contribution of the paper is a demonstration of how the current imposition of a strictly positive additive value structure can lead to incorrect preference ratios and even incorrect ranking of alternatives. The proposed preference elicitation and computation method solves these problems in a simple and intuitive manner.Scope and purposeWe focus in this paper on common cases where the AHP is used to evaluate alternatives in light of multiple criteria and where at least some of the considerations involve negative rather than positive effects from the point of view of the decision maker. The main objective is to correct how such negative effects are evaluated within the AHP.