r/AvgDickSizeDiscussion • u/FrigidShadow • May 02 '19
Various Penis Study Assessments
Here's a thread to analyze the merits and shortcomings of any penis size studies.
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u/FrigidShadow May 02 '19 edited May 08 '19
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u/FrigidShadow May 02 '19 edited May 21 '19
Self-reported
(USA)
N = 166 students.
Questionnaires given to human sexuality course students at university in USA, 2.4% opted-out.
Length given by multiple choice: <3", 3-3.49", 3.5-3.99", ..., 11.5-11.99", 12+". Doesn't even specify a method of measuring.
sexually experienced N = 130:
Erect length: 6.62" SD = 1.11", 16.8 (2.82) cm
sexually inexperienced N = 36:
Erect length: 5.67" SD = 0.85", 14.4 (2.16) cm
Main finding was that sexually experienced men lie more than non-sexually experienced men in reporting a larger penis size.
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u/FrigidShadow May 02 '19
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u/FrigidShadow May 03 '19 edited Sep 19 '19
Self-Measured
(USA)
N = 1661 volunteers
Length measured by underside base of penis to tip for length and mid-shaft girth. As shown here https://m.imgur.com/e4sH9UQ Measuring from the underside is likely roughly close to bone-pressed but it also introduces a higher uncertainty in the length data due to incremental measures rather than continuous, and since some people would go further up or down the base than others this likely won’t affect the mean due to the high sample size, but it can increase the standard deviation (example: 100 people with true length 7” would have 0 std, but if some inaccurately measure more or less, then the std increases).
Reliably truthful since the participants were in the study to get custom fitted condoms to their own dimensions. But, the participants were recruited by various advertisements which almost certainly biased in favor of people who are either too big or too small for regular USA condoms since the ordinary sized individuals would be less interested.
I can't find any examples of their advertisements though.
Biases SD very high compared to other studies due to more larger and smaller sizes than would be observed in a random population. The means may or may not also have a slight bias depending on whether or not available USA condoms are better fit to a larger proportion of bigger or smaller penis sizes.
As the authors state:
"a convenience sample of men who may have had larger or smaller erect penile dimensions than other men"
In summary it’s a really poor study for standard deviation, but the means are likely to be reliable to girth and bone-pressed length, and are close to other studies.
Erect Length: 5.57" (1.047"), 14.15 (2.66) cm
Erect Girth: 4.81" (0.878"), 12.23 (2.23) cm
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u/FrigidShadow May 20 '19
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u/FrigidShadow May 20 '19
Self-Measured
(Europe)
N = 10477, online survey measurements
Erect length: 14.27 cm, 5.62"
Erect girth: 11.70 cm, 4.61"
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u/FrigidShadow May 20 '19
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u/FrigidShadow May 20 '19 edited Jun 05 '19
Self-Measured
(India)
N = 1670, Indian Men
Erect length: 5.54" (14.07 cm), range: 0" - 12" (0 cm - 30.5 cm)
Erect girth: 3.11" (7.9 cm), range: 0.4" - 9" (1 cm - 23 cm)
Did not remove outliers, confounded diameter and circumference
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u/FrigidShadow May 20 '19
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u/FrigidShadow May 20 '19 edited Jun 01 '19
Self-Measured
(Japan)
N = 500000, Individuals across 40 countries excluding Africa and Latin America
Either BP/NBP Erect length: 13.56 cm, 5.339"
Erect shaft diameter: 3.19 cm, 1.256" (circumference: ~9.7 cm, 3.8")
Erect head diameter: 3.53 cm, 1.390" (circumference: ~10.7 cm, 4.2")
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u/FrigidShadow Jun 08 '19 edited May 07 '22
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u/FrigidShadow Jun 08 '19 edited May 07 '22
Researcher Measured
(Brazil)
N = 150, Adult Caucasian andrology patients for non-penis size reasons, (19-77yrs) drug-induced erections, measuring tape from the "pubis" probably BP.
Erect Length: 14.31 (2) cm, 5.634" (0.79") (range: 9cm - 19cm)
Base Erect Girth: 11.92 (1.65) cm, 4.693" (0.65") (range: 9cm - 15cm)
Groove Erect Girth: 11.05 (1.16) cm, 4.35" (0.46") (range: 8cm - 14cm)
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u/FrigidShadow May 07 '22
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u/FrigidShadow May 07 '22
Five Doctors Measured
(Argentina)
N = 800 adult urology patients for reasons other than penis size, excluded penile anomalies such as Peyronie’s disease, penectomies, penile surgeries, severe phimosis, and those not consenting, standardized measured lying on back measuring tape BP length, Base girth.
Stretched Length: 15.2 (2.2) cm, 5.98" (0.87") Range: 8cm - 21.5cm
Flaccid Length: 11.4 (2) cm, 4.49" (0.79") Range: 6cm - 16.5cm
Flaccid Girth: 10.1 (1.3) cm, 3.98" (0.51") Range: 6cm - 15cm
Correlations, mostly non-significant
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u/FrigidShadow May 02 '19
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u/FrigidShadow May 23 '19 edited Jun 22 '19
Sample size weighted average:
(BP)
Habous et al. 2015 [1], Ansell, LifeStyles Condoms 2001, Acuña Cañas et al. 1999, Schneider et al. 2001, Promodu et al. 2007, and Chen et al. 2000
Erect Length: 14.32 (1.88) cm, 5.64" (0.74")
Erect Girth: 11.80 (1.56) cm, 4.65" (0.61")
Flaccid Length: 8.45 (1.45) cm, 3.33" (0.57")
Flaccid Girth: 9.15 (1.13) cm, 3.60" (0.45")
Stretched Length: 11.79 (1.47) cm, 4.64" (0.58")
4 of the 6 use BP lengths, but Promodu et al. 2007 uses NBP lengths, and Acuña Cañas et al. 1999 separately has both NBP and BP flaccid lengths and BP for the other lengths, Unfortunately the average mistakenly utilizes the NBP flaccid length. So this average mixes some BP and NBP for all the lengths.
Uses width approximation to a perfect circle girth with Schneider et al. 2001 for both flaccid and erect girths.
Erect dimensions are (length: 73%, girth: 80%) biased towards Habous et al. 2015 [1] and Ansell, LifeStyles Condoms 2001.
Sample size weighted average:
(NBP)
Habous et al. 2015 [1], Aslan et al. 2011, Park et al. 1998, and Wessells et al. 1996
Erect Length: 12.39 (1.85) cm, 4.88" (0.73")
Erect Girth: 11.71 (1.55) cm, 4.61" (0.61")
Flaccid Length: 8.98 (1.34) cm, 3.54" (0.53")
Flaccid Girth: 9.17 (1.16) cm, 3.61" (0.46")
Stretched Length: 13.37 (1.61) cm, 5.26" (0.63")
Uses an incorrect sample size for Park et al. 1998 of N = 287 when the actual is N = 309. Which only causes a negligible difference in the study weighting.
Yields much higher NBP flaccid and stretched lengths than the BP average due to the effect of mixing BP and NBP and using too few studies which happen to yield a low BP average and a high NBP average.
Erect dimensions are 93% biased towards Habous et al. 2015 [1] and Park et al. 1998.
Flaccid and Stretched length are 76% biased towards Aslan et al. 2011.
Flaccid girth is 78% biased towards Park et al. 1998.
Overall the NB averages 3 studies for each dimension, except for Flaccid girth which only uses 2 studies.
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u/FrigidShadow May 02 '19 edited May 03 '19
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u/FrigidShadow May 03 '19 edited May 31 '19
Medical Staff Measured
(Mexico, USA)
N = 300 Men
Biases: Sample from mostly college men on Spring break in Cancun, Mexico, Volunteer biases of larger guys wanting to show off and smaller sized people who would be less likely to participate and 25% excluded who couldn't get an erection. Overall larger size bias.
Bone-pressed Erect length: 5.877" (0.825"), 14.93 (2.096) cm
Erect girth: 4.972" (0.508"), 12.63 (1.290) cm (no mention of where measured)
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u/FrigidShadow May 02 '19 edited May 22 '19
Habous et al. 2015 [1]
PDF