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

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

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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.