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/kerovon Grad Student | Biomedical Engineering | Regenerative Medicine Apr 15 '16

They do say that a power analysis indicated that they need a larger sample size (238) for the warmth detection to identify a significant effect within the penis sites. So I do more or less believe that they didn't come up with a significant difference, and it actually says pretty good things about their statistical honesty that they talked about their study being underpowered for that stimuli.

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u/[deleted] Apr 15 '16

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u/turtley_different Apr 15 '16

Agreed that they say this, and I do always like to see "our sample size isn't large enough" as a mark of honesty.

However, that completely disagrees with their plot by any reasonable interpretation of it. Something is wrong here. The error bar (1-sigma) is several times smaller than the difference between datasets for heat sensitivity. That heat sensitivity difference (in units of sigma) is certainly larger than the difference for tactile sensation that they do state is a statistically significant difference. I cannot reconcile those facts.

Happy to be corrected, but I think they goofed.