QoE beyond the MOS: Added value using quantiles and distributions

Traditionally, Quality of Experience (QoE) assessment results (or objective estimations thereof) are presented as a single scalar value, typically a Mean Opinion Score (MOS). While useful, the limitations of MOS are evident even in its name; for many applications, just having a mean value is simply not enough. For service providers in particular, it would be more interesting to have an idea of how the scores are distributed, so as to ensure that a certain portion of the user population is experiencing satisfactory levels of quality, thus reducing churn. In this paper we propose different statistical measures to express important aspects of QoE beyond MOS like user diversity, uncertainty of user rating distributions, ratio of dissatisfied users. Further, we propose a way to use MOS values and the standard deviation of opinion scores (SOS) hypothesis, which postulates a quadratic relation between subjective scores and their standard deviation, in order to derive quantiles for subjective ratings.