I have read many websites saying that it was self measured with cards. I think the cards were then posted in anonymously. Still ended up with a bunch of liars adding on the extra inch. If you look at the difference between self and nonself measured surveys, the self ones are always higher.

IMO the only survey that is useful was the italian army one, I think the average ended up 4.9”, it is the only survey I trust since I presume they were all forced to take part. No guy with a tiny cock is going to go along freely to a survey to has his tiny 3” measured by a nurse and risk humilitation. Whereas a 8” guy would jump at the chance to take part.

The "average size" is usually over-estimated. Small guys don't take part in surveys and big guys jump at the chance.

Girl claims she had a huge ex? Stick a spider in the bathroom or a mouse in the kitchen and when she comes out screaming ask her how big the spider/mouse was...