Investigations on the role of expectations and individual decisions in quality perception

In the scientific field of Quality of Experience (QoE) the impact of technical influencing factors — often referred as Quality of Service (Qos) — and additional context factors like applications, usage scenarios, emotional state, etc. on the subjective quality assessment is examined. Nevertheless, two relevant aspects have been neglected so far in QoE related research: user expectations and user decisions. Hence, a literature study is presented which explains how expectations are addressed in related research fields and how individual expectations can be quantified. Based on that, four empirical user studies are discussed which show how to trigger quality-related expectations in a laboratory setup and which methodological aspects need to be considered. Based on the concept of desired and adequate expectations [11], questionnaires have been used to measure individual expectations in the context of video on demand and telecommunication providers. This information is furthermore used to enhance the prediction accuracy of quantitative QoE models up to 12%. A failure to fulfill quality-related user expectations may entail certain user decisions, e.g., the technical video quality of a streamed video is increased, which also includes higher fees. For this reason, three user studies are discussed which have examined the impact of economic user decisions on QoE. In these studies the test participants were able to spend real money for enhanced video quality. According to the discussed findings, the individual decision regarding quality and price has a positive impact on subjective quality assessment. Moreover, recommendations are presented which can be used for further QoE experiments including economic decisions. The impact of non-economic decisions on QoE assessment is investigated by three user studies, which focused on the impact of individual decisions regarding quality impairment, end device and content. So far, the ambiguous results of these three user studies make it impossible to draw final conclusions regarding the impact of non-economic user decisions on quality assessment. Finally, both user-related QoE-aspects — user expectations and user decisions — are presented in the framework of the quality formation process [12] which describes the interaction between expectations, decisions and subjective quality assessment.