I don’t know if people would lie about their results from a self-reported girth study, simply because most men don’t know how big around an erect penis should be. In contrast, most men believe that the penis should be 6 inches long and are more likely to report their length being 6 even it is not.
This is a solid point, guys are certainly less likely to straight up lie about their girth than length, but I don’t really think guys lie so much as round up. Although girth may be spared of the purposeful exaggeration that length is, it’s certainly not exempt from human tendency to round it to a favorable number. We are way more exact/precise on this forum than the general population. To them 5 10 1/2 is 6 foot in a colloquial conversation much in the same way that 4.6 girth is pretty much 5 and 5.3 is pretty much 5.5, 5.6 is probably 6 way more often than someone correctly rounds down. 4.2 isn’t 4, etc. I think it’s ironic that the number is always so arbitrary as saying “5 inches” has any verified study ever measured 5+ inches, I don’t think it has. Even in self studies it sometimes doesn’t measure this high, and a lot of the self studies include head girth.
Maybe/probably with the head girth and based girth all involved in the measurement, and the largest one gets picked, I could see 5. Otherwise (I.E random spot on shaft) not a chance.