Equipment Size: What is average?

Normal Curves: Sexy Science, Serious Statistics

Today’s deep dive: the surprisingly serious science of penis size. Using self-report surveys, objective measurements, and a healthy dose of old-school statistics, we ask: How do you get clean data on gentlemen’s goods?Along the way, we explore social desirability bias, survey design tricks, and what happens when science meets insecurity. You’ll never look at a Starbucks cup the same way again.

Statistical topics

• Social desirability bias
• Selection bias
• Volunteer Bias
• Descriptive Statistics
• Right-Skewed Distributions
• Strategies to improve accuracy in self-report data

Methodological morals

• “When answers aim to please, truth takes its leave.”
• “Without descriptive statistics, you'll never know if you measure up.”

References

• CROWNE DP, MARLOWE D. A new scale of social desirability independent of psychopathology. J Consult Psychol. 1960;24:349-354. doi:10.1037/h0047358
• Gebhard, P.H. and Johnson, A.B., 1998. The Kinsey data: Marginal tabulations of the 1938-1963 interviews conducted by the Institute for Sex Research. Indiana University Press.
• Herbenick D, Reece M, Schick V, Sanders SA. Erect penile length and circumference dimensions of 1,661 sexually active men in the United States. J Sex Med. 2014;11(1):93-101. doi:10.1111/jsm.12244
• Johnston, L., McLellan, T., & McKinlay, A. (2014). (Perceived) size really does matter: Male dissatisfaction with penis size. Psychology of Men & Masculinity, 15(2), 225–228. https://doi.org/10.1037/a0033264
• King BM. The Influence of Social Desirability on Sexual Behavior Surveys: A Review. Arch Sex Behav. 2022;51(3):1495-1501. doi:10.1007/s10508-021-02197-0
• King BM. Average-Size Erect Penis: Fiction, Fact, and the Need for Counseling. J Sex Marital Ther. 2021;47(1):80-89. doi:10.1080/0092623X.2020.1787279
• King BM, Duncan LM, Clinkenbeard KM, Rutland MB, Ryan KM. Social Desirability and Young Men's Self-Reports of Penis Size. J Sex Marital Ther. 2019;45(5):452-455. doi:10.1080/0092623X.2018.1533905
• Larson, R.B., 2019. Controlling social desirability bias. International Journal of Market Research, 61(5), pp.534-547.
• Stodel, M. (2015). But What Will People Think?: Getting beyond Social Desirability Bias by Increasing Cognitive Load. International Journal of Market Research, 57(2), 313-322. https://doi.org/10.2501/IJMR-2015-024 (Original work published 2015)

Spreadsheet with Penis Length Data

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• (00:00) - Introduction
• (02:33) - Starbucks metric and episode themes
• (07:17) - Men and women’s sampling frames
• (09:24) - Kinsey and his studies
• (14:59) - Statistics quiz on Kinsey penis data
• (21:16) - Social desirability bias
• (28:23) - Cognitive tricks to elicit honest survey answers
• (34:16) - Condoms, honest penis lengths, and another stats quiz
• (40:36) - Objective penis appraisers, measurement error, and reliability
• (45:48) - Whose penises? Volunteer and selection bias
• (49:33) - Mini-meta-analysis and the “answer”
• (51:12) - Wrap-up and methodological morals