All certified members from that site must submit a picture of their erected penis with the scale tag put on. Base on this they can easily estimate the size using proportion. As I mentioned in the beginning to have it clear: measurement is BPEL along top side. I passed such a validation myself, they were correct.
I paid a fee, so I can check with other members and see their galleries and measuring pictures. From what I've seen so far, there is full range of sizes and there is no such thing like self reported size, everything must be verified.
Just don't get me wrong, I'm not saying this is only correct and official data. I have a opportunity to check this I'm sharing this with you.
Any questions, please ask.
6.3" to 6.4" is the average of guys that use their site to compete & see who has the biggest penis. It's not the average of the general population of the world.
So the "average" is the virtual penis average, not the "average" for anything else.

