Well, this sort of data is very difficult to judge. As it states the Kinsley respondents measured themselves in private. That alone will create a rather larger (no pun!) discrepancy. Before PE I had ALWAYS considered myself 5.5” nbpel. When I measured my starting stats I got 5.875” ebpl. In reality, my nbpel was 5.125” and yes I had measured myself many times before it was just that I wanted to “believe” I was bigger and therefore the ruler somehow got pressed into the skin somewhere between non and bp. In the Kinsley test I would bet that many did the same.
Girth is a little more consistent but still there is a fudge factor concern. I use a 3/4” wide strip of paper that I have marked as a ruler. This shows me when I am measureing myself squarely. If you measure at an angle you end up measureing an oval which gives a larger reading. My starting stats measured 4.5” eg. Even so, I realized that I had NOT completely tightened the tape! In reality my starting stat was 4.375”. Again, I wanted to believe.
Now, after 6 months of less than aggressive PE, I am at 5.875” nbpel, 6.625” bpel, 4.75” eg… and GROWING.
Bottom line, I think a RANGE is the best average. Below the range is small and above is large. Within is average. I would bet the true NPBEL average is 5.5 to 6.0 and the EG is 4.5-5.0.