We demonstrate in this paper the relationship between viewer QoE (quality of experience) and MOS (Mean Opinion Score) and the HTTP Adaptive Streaming Video Quality (VQ) rate. We will show that MOS scores are impacted by the variance (or standard deviation-SD) of the VQ rate more so than the mean VQ level. Correlation between MOS and the standard deviation of the delivered VQ rate is 2:1 greater than between MOS and the mean VQ rate. In other words users care more about maintaining a consistent VQ level than they do in a higher bit rate. We also show that inelasticity exists between the mean VQ rate and MOS scores, where multi megabit changes in VQ rates result in only modest changes in MOS scores. Finally we demonstrate that we can accurately predict MOS scores incorporating both the mean VQ level and the SD of the VQ level. Two analytical methods are given for predicting MOS, and are shown to have a high correlation and low error.