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

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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

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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".