I think the study would have been much better with the option of "I think I'm about average." As is you are forced to say you are above or below, which I tend to think would lead to more people choosing above than otherwise would have.
Interesting point. Of the remaining 35%, I wonder what fraction think they are about average and what fraction thinks they are below average.
If the statement that you are asked to agree or disagree with is “I am more intelligent than the average person.”, and you think you are average in intelligence, you can say you disagree, which does not mean you think you are below average in intelligence.
