You can’t compare scores generated using Telephone interviews and Internet Surveys.
Past research has suggested that telephone surveys exhibit a response effect resulting from acquiescence, social desirability, and primary and recency effects.
People want to be agreeable when talking to people but less so when doing an internet survey so telephone survey results are higher.
And also the simple audio vs. visual presentation of the survey changes the score. Primary and recency effects result when respondents are drawn to the first or last response option presented to them.
This drags the scoring to the ends of the scale: you get more 9s and 10s and 0′s and 1′s. This is particularly problematic in the net scoring approaches.
Itcertainlydoes not meetyourquestion, but I hope is interesting take into account.