Editing Mean Opinion Score (section)

=== Statistical and Methodological Issues ===

MOS faces several inherent limitations that researchers and practitioners must consider:

'''Ordinal Scale Problems''': MOS ratings are based on ordinal scales where the ranking of items is known but intervals between ratings are not necessarily equal. Mathematically, calculating an arithmetic mean from ordinal data is problematic, and median values would be more appropriate. However, the practice of using arithmetic means is widely accepted and standardized.<ref>https://en.wikipedia.org/wiki/Mean_opinion_score</ref>

'''Range-Equalization Bias''': Test subjects tend to use the full rating scale during an experiment, making scores relative to the range of quality present in the test rather than absolute measures of quality. This prevents direct comparison of MOS scores from different experiments.

'''Contextual Dependence''': MOS values are influenced by the testing context, participant demographics, and the presence of anchor stimuli (very high or low quality samples that influence perception of other stimuli).