Motivated by the literature on preference elicitation and welfare analysis, Chapter I studies the properties of aggregators of choice datasets into preferences. Novel normative principles and their theoretical implications are provided. I analyse numerous approaches proposed by the literature in view of the introduced principles. I also propose and characterize two counting procedures that are foundational for the analysis. Motivated by the theoretical framework of the first chapter, in Chapter II, I propose a novel experimental design to test two normative principles: (1) Informational Responsiveness guarantees that no choice data is ignored; (2) Revealed Preference constrains the preference elicitation process to a particular reo...