Goal models have been found to be useful for supporting the decision making process in the early requirements phase. Through measuring contribution degrees of low-level decisions to the fulfilment of high-level quality goals and combining them with priority statements, it is possible to compare alternative solutions of the requirements problem against each other. But where do contribution measures come from and what is the right way to combine them in order to do such analysis? In this paper we describe how full application of the Analytic Hierarchy Process (AHP) can be used to quantitatively assess contribution relationships in goal models based on stakeholder input and how we can reason about the result in order to make informed decisions. An exploratory experiment shows that the proposed procedure is feasible and offers evidence that the resulting goal model is useful for guiding a decision. It also shows that situation-specific characteristics of the requirements problem at hand may influence stakeholder input in a variety of ways, a phenomenon that may need to be studied further in the context of eliciting such models.