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Index/Topics/Sampling bias

Sampling bias

The topic is about how the selection of participants for studies can introduce bias and affect the results.

Fact-Checks

2 results
Jan 22, 2026
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Are there reliable demographic differences in penis girth by age or ethnicity in US studies?

The short answer: no robust, evidence proves reliable demographic differences in ; published analyses report small average differences in some datasets but methodological heterogeneity and heavy overl...

Feb 3, 2026

How do measurement methods (self‑reported vs clinician‑measured) change reported penis size distributions?

Studies and meta-analyses show a consistent divergence: self‑reported tend to be larger than measurements taken by clinicians, and different (flaccid, stretched, erect) produce different central value...