Done.
I also have an issue with the primary purpose of owning a firearm, kinda. I shoot about 4,000 rds./yr. at my gun range, so target shooting would seem to be my primary reason for owning a gun, or 62 to be specific. However, if for some reason I could not have access to shoot recreationally I would still have a firearm for self/home defense, even though I have never even drawn a gun for this purpose.
I put down "home" defense as my primary reason although "self" defense would also qualify (I can carry in 24 states although not my own). I believe that combining these two answers would give a more accurate picture of gun ownership. but I suppose this can be done in the final analysis of the data.
As far as the question regarding "sporting" use, I put down "competetive target shooting" although I do not compete. It was the closest answer for my situation.
Good luck on your degree.