Clever methodology! And a fascinating topic. I wonder though about possible confounding selection biases to do with the sample of johns.
First: Men who use prostitutes are on average of lower social status. Black men are on average of lower social status. Could men with small penises also be on average of lower social status? If so, then you could be seeing an effect that men from higher social status ethnicities are mostly likely to use a prostitute if they have a small penis, whereas black men are nearly always of lower social status, so you are seeing their full range of penis sizes.
Second: Similar to above, but with the idea that white and Asian men would mostly only feel the need to use a prostitute if they were small-penised, whereas black men have such high libido that they visit prostitutes even if their penis is large. Again suggesting that a large range of black men visit prostitutes but only an unrepresentative sample of white and Asian men use them, selected specifically for their small penis size.
There is also the issue of showers-vs-growers. Black men, because of evolving in a hot environment, do not need to have their penes shrink much when not erect. Are the prostitutes all only reporting on erect size? Even if they intended to, these are just their self-reported impressions and as such may be biased by their simultaneous recollections of the flaccid size.
You could try interviewing Men who have Sex with Men (MSMs) as they would also see a wide variety of penii. Though that would also have selection biases, including that studies seem to show that homosexual men have larger penis size than average to begin with.
Thanks for the comments. I agree there could be some sort of selection effects, I just don't find the idea of a penisXrace interaction in who goes to visit sex workers particularly likely. Or much of an interaction with the other questions either.
At the end of the day, we really need the hard evidence and should be directly measuring penis differences in the clinic. Large sample, standardised method etc. It's especially important I think for ensuring blacks get condoms of the right size. I will hopefully be writing much more on this issue soon.
Edit - we do discuss the issue of selection effects in the discussion section. I'll copy it here. We don't have a strong response other than to say that we think any large selection biases seem fanciful
"However, this could also create ascertainment bias if judgement of
the races influences whether sex workers choose to accept them as clients. There
are other potential forms of ascertainment bias in our sample. It is not impossible
that there are race-trait interactions in determining whether men seek out sex
workers in the first place. It is also possible that sex workers who take online
surveys for money have unusual judgements of the races. The greater tendency
of Blacks to visit sex workers (Johnson et al., 1994), and the possibility that sex
workers discriminate against them (McNeill, 2010; Vanguard, 2015), may induce
a bias in the responses of sex workers. Nonetheless, we fail to imagine any
particularly strong effects from such ascertainment biases."
Clever methodology! And a fascinating topic. I wonder though about possible confounding selection biases to do with the sample of johns.
First: Men who use prostitutes are on average of lower social status. Black men are on average of lower social status. Could men with small penises also be on average of lower social status? If so, then you could be seeing an effect that men from higher social status ethnicities are mostly likely to use a prostitute if they have a small penis, whereas black men are nearly always of lower social status, so you are seeing their full range of penis sizes.
Second: Similar to above, but with the idea that white and Asian men would mostly only feel the need to use a prostitute if they were small-penised, whereas black men have such high libido that they visit prostitutes even if their penis is large. Again suggesting that a large range of black men visit prostitutes but only an unrepresentative sample of white and Asian men use them, selected specifically for their small penis size.
There is also the issue of showers-vs-growers. Black men, because of evolving in a hot environment, do not need to have their penes shrink much when not erect. Are the prostitutes all only reporting on erect size? Even if they intended to, these are just their self-reported impressions and as such may be biased by their simultaneous recollections of the flaccid size.
You could try interviewing Men who have Sex with Men (MSMs) as they would also see a wide variety of penii. Though that would also have selection biases, including that studies seem to show that homosexual men have larger penis size than average to begin with.
Thanks for the comments. I agree there could be some sort of selection effects, I just don't find the idea of a penisXrace interaction in who goes to visit sex workers particularly likely. Or much of an interaction with the other questions either.
At the end of the day, we really need the hard evidence and should be directly measuring penis differences in the clinic. Large sample, standardised method etc. It's especially important I think for ensuring blacks get condoms of the right size. I will hopefully be writing much more on this issue soon.
Edit - we do discuss the issue of selection effects in the discussion section. I'll copy it here. We don't have a strong response other than to say that we think any large selection biases seem fanciful
"However, this could also create ascertainment bias if judgement of
the races influences whether sex workers choose to accept them as clients. There
are other potential forms of ascertainment bias in our sample. It is not impossible
that there are race-trait interactions in determining whether men seek out sex
workers in the first place. It is also possible that sex workers who take online
surveys for money have unusual judgements of the races. The greater tendency
of Blacks to visit sex workers (Johnson et al., 1994), and the possibility that sex
workers discriminate against them (McNeill, 2010; Vanguard, 2015), may induce
a bias in the responses of sex workers. Nonetheless, we fail to imagine any
particularly strong effects from such ascertainment biases."
An important and noble ambition indeed. It is fitting that you are announcing this vital work during Pride Month and in the week of Juneteenth.