This work addresses the evaluation of interaction techniques for decision-making tasks performed by non-experts in the context of multi-objective optimization problems. Such tasks require making trade-offs between antagonistic criteria, according to individual subjective preferences. Evaluating such techniques is made difficult by the subjective nature of such tasks, as well as by a lack of rigorous methods for assessment. Our primary contributions to this problem are two-fold: (1) a set of subjective metrics including decision accuracy, choice satisfaction, and incentives to explore; (2) the use of a pragmatic approach to map these subjective metrics onto objective quantitative measures. To illustrate how this subjective-objective mapping can be performed in a pragmatic manner, we have conducted an experiment involving 177 participants to objectively measure and compare two multi-slider interaction techniques for decision-making tasks performed by non-experts in the context of domestic energy management. The results of this evaluation constitute a secondary contribution.