I have a survey about 6 vendors' rating scores.
20 people were asked to rate n requirements for each vendor.
The overall vendor's assessment should be the average of those requirements.
My question is what are the right formula to calculate vendor rating's
Standard deviation and confidence interval.
Since rating came from two dimensions, from same 20 people and same n
requirements. I can not simply treat each rating as one observation hence I
have 20*N observations then use simple standard deviation formula.
Please help. Thanks!
Who knows proc surveymean? is this can be used here? thanks!
