Psychometric analysis of the mutually compensatory property of multimedia QoS

This paper quantitatively evaluates the mutually compensatory property in audio–video transmission over the Internet by the psychometric method. In our previous study, we used MOS (Mean Opinion Score) as the user–level QoS parameter; however, MOS is an ordinal scale, and therefore, its value does not necessarily represent exact difference between the observer’s sensory magnitude. In order to solve this problem, we construct an interval scale from the MOS values, utilizing the law of categorical judgment. We then examine how closely MOS approximates an interval scale. Furthermore, we obtain QoS mapping relations between application-level and user-level by the principal component analysis and multiple regression analysis. The regression formula thus derived can demonstrate how much one medium compensates for the other in a quantitative way with the interval scale.