Sereously?
Did they look at the demographics of where 7/11s are located? No.
As Don mentioned the color of the cup has an impact. The proximity of the cup to the filling station. Location, left side, right side, closest to the door, at the counters edge verses set back and raised. All of which can impact the selection.
I'll bet half the people buying did not even notice the survey when they selected their cup.