People may not judge the top and bottom of the scale the same. If a subject uses only half the scale, the differences reported will be less. This scaling would be done only among subjects that have seen the same material. There was a comment that one lab used a completely different scaling method than the others - knobs rather than sliders. Another noted that if the result didn't change from test to test, some labs counted it was a vote with the same scale while others counted it as a missing vote.
Some method is needed to show a decision was made.
Leon Stanger was not present. The results of the last G-2.1.6 meeting were recapped, leading to the new plan proposed by Andrew Watson, Ann Marie Rohaly and John Libert. The new plan had not been completed by this meeting, but John Libert agreed to talk about the basic idea behind it. Under the modified plan, we would produce impaired video exhibiting various degradations. Looking at some number of samples at different impairment levels, we ask the subject to provide a numerical rating between the samples at impairment levels.