Parallax error on measuring length
How accurate are we on measuring length? I first thought it’s about how dense the marks on the ruler are. Then I realized that the level of erection at the time of measuring can add or subtract ½ an inch. The placement of the ruler versus the pubic bone and how hard you push also count for a difference of 1/8”. Keeping the penis + ruler perpendicular to the body, or inclined, count also for 1/8” variation.
I thought I had reasonably accurate measurements. My ruler has millimeter marks (0.039”). I take measurements at different times around the official measuring date to eliminate the random effect of variable erection level. I have a consistent placement of the ruler and I try to keep the measuring setup perpendicular to the body.
The doubts rose when measuring BPFSL. I’ve noticed I have a consistent difference when measuring BPFSL holding the ruler with my right hand (pulling with my left) versus the other way around. Why I always get less length when pulling with the left hand and a lager BPFS length when pulling with the right? There is no such a difference in the strength of pulling and anyway I was pulling to the limit both with the right and left hand. Then I realized it was the position of my head (eyes) that was different. I had my head more forward when pulling with my right hand, so the imaginary line from my eyes to the tip of the penis intersected the ruler farther from the body. I noticed a consistent difference of 3-4 mm (1/8”).
Now I had to review the way I was measuring BPEL and NBPEL. Though I always had the best intentions not to cheat and tried to have my eyes correctly positioned on the vertical of the measuring target, the subconscious desire for a larger value made me lean forward a bit too much. This became apparent after I’ve manufactured a simple device attached to the ruler. It is capable of sliding along it, with a perpendicularly oriented plain surface that has to come in contact with the tip of the penis. It completely eliminates the parallax effect that made all previous length measurements a bit subjective. This was a huge step in making the measurements truly objective, but it lead to a slight disappointment. Though I’m convinced that since the last measurement I have gained erect length (and the BPFSL confirms it), with the new objective measuring device I had to accept the same value I had a month ago… But at least now it’s certain!
With the visual method I measured 1/8” more than with the contact method. I have no intention to fool myself (or others), so I’ll stick with the objective method from now on.
Starting BPEL: 6.9" (Dec.1st, 2008)
Current BPEL: 8.11" NBPEL: 7.63" BPFSL: 9.09"
Current MEG : 5.6"