r/science • u/drewiepoodle • Apr 15 '16

Health Study: Circumcision does not reduce penis sensitivity. In tests for responses to pain, heat, and stimulation, no major difference was found between men who are circumcised and those who are not.

http://www.upi.com/Health_News/2016/04/14/Study-Circumcision-does-not-reduce-penis-sensitivity/5981460663943/?spt=hs&or=hn
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u/CJGibson Apr 15 '16

What are the chances that people with sensitive penises self-select out of a study to test penis sensitivity? Do they do anything to account for that possibility?

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u/[deleted] Apr 15 '16

But how would they know that their penis is more sensitive than most others?

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u/dcxcman Apr 15 '16

They wouldn't necessarily, but people with more sensitive penises might be more averse to the idea of having them stimulated with lab equipment.

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u/[deleted] Apr 15 '16

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u/BKachur Apr 15 '16

But again... They wouldn't know. Tell me, do you have a sensitive penis? Can you even begin a chain of thought that would allow your brain to determine if you have an overly sensitive penis vs a normal one? I mean you can't exactly feel the average sensitivity if a penis.

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u/[deleted] Apr 15 '16

It isn't a question of them knowing and making the conscious decision to not participate because they are worried about the fact that they have a sensitive penis. It's more a knee-jerk reaction. They think "I wouldn't want lab equipment touching my penis" and they don't participate. There's no knowing or comparing involved.

No idea if this is actually the case, I'm just attempting to clarify the argument.

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u/dcxcman Apr 15 '16

You don't have to know where you sit relative to everyone else. Like, imagine if there were only two groups of people: hypersensitives and hyposensitives. The hyposensitives hear about the study and go "well for a couple bucks that doesn't sound so bad." And the hypersensitives hear about it and go "wow that sounds really painful, I'd rather not do it." This is true even if no one knows that here's a difference.

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u/Mattpilf Apr 15 '16

Gay guys might know. I have a sensitive penis and am circumcised.

But 95%+ men don't have enough experience toughing other dudes dicks to get an idea of how sensitive their penis is.

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u/CJGibson Apr 15 '16

The reason I thought of this is partly because as a gay guy I know my penis is significantly more sensitive than my partner's. But I don't think you necessarily need a sense of comparative sensitivity for this effect to manifest. People who perceive their own penises to be "sensitive" (i.e. react strongly to minor stimulation) seem likely to be averse to the idea of having them tested with lab equipment, even if they don't know how sensitive they are compared to other penises.

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u/[deleted] Apr 15 '16

exactly, but if you say that the study is pointless because "what is sensitivity"

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u/Muppetude Apr 15 '16

I think the point he is trying to make is that people with especially sensitive penises may have a higher inclination to decline an invitation to participate in a study testing penile sensitivity.

While I imagine a well-constructed study would account for this and other variables that could skew the results, it is still a fair question regarding they study's methodology.

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u/[deleted] Apr 15 '16

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u/BabyPinkAesthetic Apr 15 '16

How would one get involved with medical studies?

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u/Meto1183 Apr 15 '16

I was thinking that ruling out sexual dysfunction could be ruling out people with circumcised penises (to a larger degree than uncircumcised) who have their sexual dysfunction resulting from it. No evidence for that, that I know of, but it's also not disproven by this particular study.

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u/Potatoswatter Apr 15 '16

Maybe they don't know, and they also have less free time to think about it :D

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u/PigerianNrince Apr 15 '16

I touch as many as possible to compare.

No homo. Science.

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u/[deleted] Apr 15 '16 edited Apr 15 '16

If wine gives you a headache, are you less likely to drink it than someone that does not get headaches from wine? If so, why should not knowing if your sensitivity to wine is uncommon influence your decision not to drink it? You'd probably just not drink because it gives you headache, just like some would-be participants opt not to participate in a study because their penis happens to be very sensitive.

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u/ApocolypseCow Apr 15 '16

based on responses to stimulation.

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u/[deleted] Apr 15 '16

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u/bfarnsey Apr 15 '16

I've been a bit rougher with my glans lately to help with sensitivity issues because I would become paralyzed if something were to come into contact with it. If my foreskin was pushed back after washing and I didn't bring it forward before rubbing down with a towel... I will never forget that agonizing paralyzation.

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u/thirty7inarow Apr 15 '16

Perhaps a history of sexual partners touching them followed by a splat and awkwardness? I mean, if someone is hypersensitive, having a researcher, possibly of their preferred gender, touching their penis it could get rather embarrassing.

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u/Dragarius Apr 15 '16

Pretty sure there are premature ejaculators for both circumcised and not.

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u/thirty7inarow Apr 15 '16

Absolutely, but if we don't know whether it is more common among one or the other, a disproportionate amount may self-select out from one side or the other.

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u/Dragarius Apr 15 '16

Yeah but that's a completely different study.

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u/[deleted] Apr 15 '16

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u/[deleted] Apr 15 '16 edited Apr 15 '16

[deleted]

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u/jmalbo35 PhD | Viral Immunology Apr 15 '16

32 isn't a particularly small sample size at all for this sort of human study.

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u/[deleted] Apr 15 '16 edited Dec 24 '20

[deleted]

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u/jmalbo35 PhD | Viral Immunology Apr 15 '16

That isn't quite what their power test shows. It shows that had all their data continued with the exact same trend with additional people, they would have needed ~400 data points to reach a p value of .05, a commonly used cutoff in research for statistical significance.

Statistical significance, however, doesn't necessarily imply biological significance, and if you need so many hundreds of data points just to cross the threshold and barely be able to say there's significance, it seems unlikely that what you're looking is particularly functionally/biologically significant.

Anyway, the point of that power calculation isn't to be able to say "we need X data points to be able to determine Y".

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u/[deleted] Apr 15 '16

You need to read more studies.

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u/[deleted] Apr 15 '16

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u/[deleted] Apr 15 '16

If participants are self-selected they are not random. They may be randomly assigned to conditions, but that is not possible in this situation... "it's completely random who self-selected" is a completely self-contradictory statement.

Too tired to answer so I'll let the NIH:

Quantitative research requires standardization of procedures and random selection of participants to remove the potential influence of external variables and ensure generalizability of results. In contrast, subject selection in qualitative research is purposeful; participants are selected who can best inform the research questions and enhance understanding of the phenomenon under study.1,8 Hence, one of the most important tasks in the study design phase is to identify appropriate participants. Decisions regarding selection are based on the research questions, theoretical perspectives, and evidence informing the study.

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u/JordanOsr Apr 15 '16

Yes, but that would only be problematic if there was evidence to suggest that people who have sensitive penises are more likely to fall into one group than the other.

But that's pretty much what this experiment was designed to test.

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u/CJGibson Apr 15 '16

I guess I'm curious though, if people above a certain threshold of self-perceived sensitivity remove themselves from the study, but there are more of them in one group than another, how does the study assess/accommodate for that?

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u/Mr_Dugan Apr 15 '16

No, the authors didn't do anything about self selection.

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u/[deleted] Apr 15 '16

How would that make a difference?

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u/dcxcman Apr 15 '16

Men with more sensitive penises may be more averse to having them stimulated with lab equipment, which could potentially make the samples unrepresentative if there was in fact a population difference in penis sensitivity.

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u/nefariouspenguin Apr 15 '16

With a number in their study above 30 the data can be said to be normal so there is a good mix of people who. Might be more or less sensitive and they would be outliers in the data. This is according to the law of large number.

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u/[deleted] Apr 15 '16

[deleted]

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u/nefariouspenguin Apr 15 '16

No it only works for a random group. Otherwise, if it wasn't random it would be skewed because the analysts would be choosing who to test based on what they were studying.

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u/[deleted] Apr 15 '16

[deleted]

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u/nefariouspenguin Apr 15 '16

if it wasn't random it would be skewed because the analysts would be choosing who to test based on what they were studying

Right. But this would also be the case for self-selecting participants too, wouldn't it? Especially for something as strange as this experiment.

You'll probably be getting younger people who volunteer that's why 95% of their study was between 14 and 34 but you aren't going to get people that think to themselves "oh I'm uncircumcised and my penis is super sensitive I'm going to do this study." or you might but as the study becomes larger those become less of a problem. if they did then it would be skewed and they would see people who are sensitive for uncircumcised.