First, the large variability between studies. Compared to average height or weight for example, penis size average is not known as precisely. A lot of that has to do with measurement technique.
I agree, especially with the flaccid stretched studies. My guess is that the docs don’t tend to stretch as hard as insane PEers do — and different docs will stretch with varying forces. In general, when talking about average size, I advise Thunder’s Place PEers that our measurement techniques (blood-pressed rather than bone-pressed, and with a 120% erection bent down parallel to the floor ;) ) probably exaggerate our measurements by a half-inch or more, compared to the medical studies. If you want to know how you compare to the averages in the populations that have been studied, you’d best take a normal, conservative measurement, like you might have before beginning PE, in my opinion. Extreme, maximized measurements are good for PEing purposes, so that you know whether you have really gained rather than just “improving” your measurement technique, but this kind of measurement probably isn’t best for comparison purposes. I think this partly explains why some guys claiming average size (say, 6x5) post about how all women mock their penises mercilessly as tiny; judging by some dubious measurement pics here, some guys “measuring” 6x5 probably really sport a 3x3 (only slightly exaggerating :) ).
Also, a lot of the so called studies are self reported measurements. Is self reported data valid at all?
None of the studies in that “average penis size” thread involves self-measurement. I would think that self-reports would produce a lot of exaggeration, but the Kinsey data are only about an inch or an inch-and-a-half bigger than the medical studies, and the TP self-report thread corresponds pretty well to the third-party measurement studies, so in those two cases, at least, the data don’t appear to be terribly invalid. Some other self-report studies seem wildly exaggerated, though.
Second, the wide variety of humans on the planet makes me wonder if any one study has been big and diverse enough to give an overall average for all human males. Even if that was known, wouldn’t it be more interesting to know separate averages of different races and regions?
Agreed. A big source of variability in the average size studies is likely the differences in populations the samples were drawn from. It appears that in most affluent Western countries the average dick is in the 6” range, just as the average height (for men) in these countries is in the 5’10” range today, but you’ll find substantial variation for specific regions and races due to both genetics and environment.